US20070219585A1

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Publication number: US20070219585A1
Application number: US11/724,072
Authority: US
Inventors: Douglas Cornet; Michael Manwaring; Larry Swain; Jonathan Kagan
Original assignee: KCI Licensing Inc
Current assignee: KCI Licensing Inc
Priority date: 2006-03-14
Filing date: 2007-03-13
Publication date: 2007-09-20
Also published as: JP5254200B2; CN101563118B; ZA200807412B; US8029498B2; US8771253B2; KR20080111465A; CN101454044A; JP2015198975A; MX2008011739A; JP2009529972A; JP2014204961A; EP1993651A2; CA2810300C; ZA200807377B; JP2009532080A; CN101563067A; US20130023841A1; AU2007225048B2; AU2007225049B2; AU2010257431A1

Abstract

A reduced pressure delivery system is provided and includes a primary manifold, a blockage prevention member, and first and second conduits in fluid communication with the primary manifold. The primary manifold includes a flexible wall surrounding a primary flow passage and is adapted to be placed in proximity to a tissue site. The blockage prevention member is positioned within the primary flow passage. A plurality of apertures is disposed in the flexible wall to communicate with the primary flow passage. The first conduit is fluidly connected to the primary flow passage to deliver reduced pressure through the primary flow passage and the plurality of apertures. The second conduit includes an outlet proximate the primary flow passage or an outlet of the first conduit to purge the primary flow passage or first conduit to prevent blockages.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 60/782,171, filed Mar. 14, 2006, which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a system or method of promoting tissue growth and more specifically a system for applying reduced pressure tissue treatment to a tissue site.

2. Description of Related Art

Reduced pressure therapy is increasingly used to promote wound healing in soft tissue wounds that are slow to heal or non-healing without reduced pressure therapy. Typically, reduced pressure is applied to the wound site through an open-cell foam that serves as a manifold to distribute the reduced pressure. The open-cell foam is sized to fit the existing wound, placed into contact with the wound, and then periodically replaced with smaller pieces of foam as the wound begins to heal and become smaller. Frequent replacement of the open-cell foam is necessary to minimize the amount of tissue that grows into the cells of the foam. Significant tissue in-growth can cause pain to patients during removal of the foam.

Reduced pressure therapy is typically applied to non-healing, open wounds. In some cases, the tissues being healed are subcutaneous, and in other cases, the tissues are located within or on dermal tissue. Traditionally, reduced pressure therapy has primarily been applied to soft tissues. Reduced pressure therapy has not typically been used to treat closed, deep-tissue wounds because of the difficulty of access presented by such wounds. Additionally, reduced pressure therapy has not been used in connection with healing bone defects or promoting bone growth, primarily due to access problems. Surgically exposing a bone to apply reduced pressure therapy may create more problems than it solves. Finally, devices and systems for applying reduced pressure therapy have advanced little beyond the open-cell foam pieces that are manually shaped to fit a wound site and then removed following a period of reduced pressure therapy.

BRIEF SUMMARY OF THE INVENTION

The problems presented by existing wound-healing system and methods are solved by the systems and methods of the present invention. A reduced pressure delivery system is provided in accordance with one embodiment of the present invention to apply a reduced pressure to a tissue site. The reduced pressure delivery system includes a primary manifold having a flexible wall surrounding a primary flow passage and adapted to be placed in proximity to the tissue site. The flexible wall includes an inner surface having a plurality of projections extending from at least a portion of the inner surface and into the primary flow passage. The flexible wall further includes a plurality of apertures through the flexible wall that communicate with the primary flow passage. A first conduit is fluidly connected to the primary flow passage to deliver reduced pressure through the primary flow passage and the plurality of apertures. A second conduit includes at least one outlet in proximity to the primary flow passage or the at least one outlet of the first conduit to purge blockages at or near the at least one outlet of the first conduit.

In accordance with another embodiment of the present invention, a reduced pressure delivery system is provided and includes a primary manifold having a flexible wall surrounding a primary flow passage and adapted to be placed in proximity to a tissue site. The flexible wall includes a plurality of apertures through the flexible wall that communicate with the primary flow passage. A cellular material is positioned within the primary flow passage, and the cellular material includes a plurality of flow channels. A first conduit is fluidly connected to the primary flow passage to deliver reduced pressure through the primary flow passage, the cellular material, and the plurality of apertures. A second conduit includes at least one outlet in proximity to the primary flow passage or the at least one outlet of the first conduit to purge blockages at or near the at least one outlet of the first conduit.

In accordance with still another embodiment of the present invention, a reduced pressure delivery system is provided and includes a primary manifold having a flexible wall surrounding a primary flow passage and adapted to be placed in proximity to a tissue site. The primary manifold includes a blockage prevention member positioned within the primary flow passage. A plurality of apertures is disposed in the flexible wall to communicate with the primary flow passage. A secondary manifold is positioned adjacent the primary manifold and is adapted to contact the tissue site such that the secondary manifold fluidly communicates with the primary manifold but is adapted to prevent contact between the primary manifold and the tissue site. A first conduit is fluidly connected to the primary flow passage to deliver reduced pressure through the primary flow passage and the plurality of apertures.

In another embodiment of the present invention, a method for promoting tissue growth at a tissue includes surgically positioning a primary manifold in proximity to the tissue site. The primary manifold includes a flexible wall surrounding a primary flow passage. The flexible wall includes a plurality of apertures through the flexible wall that communicate with the primary flow passage. The primary manifold further includes a blockage prevention member positioned within the primary flow passage. The method further includes surgically positioning a secondary manifold in contact with the tissue site such that the secondary manifold fluidly communicates with the primary manifold but prevents contact between the primary manifold and the tissue site. A reduced pressure is delivered to the tissue site through the primary flow passage, the plurality of apertures, and the secondary manifold.

Other objects, features, and advantages of the present invention will become apparent with reference to the drawings and detailed description that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

FIG. 1 depicts a perspective view of a reduced pressure delivery apparatus according to an embodiment of the present invention, the reduced pressure delivery apparatus having a plurality of projections extending from a flexible barrier to create a plurality of flow channels;

FIG. 2 illustrates a front view of the reduced pressure delivery apparatus ofFIG. 1;

FIG. 3 depicts a top view of the reduced pressure delivery apparatus ofFIG. 1;

FIG. 4A illustrates a side view of the reduced pressure delivery apparatus ofFIG. 1, the reduced pressure delivery apparatus having a single lumen, reduced-pressure delivery tube;

FIG. 4B depicts a side view of an alternative embodiment of the reduced pressure delivery apparatus ofFIG. 1, the reduced pressure delivery apparatus having a dual lumen, reduced-pressure delivery tube;

FIG. 5 illustrates an enlarged perspective view of the reduced pressure delivery apparatus ofFIG. 1;

FIG. 6 depicts a perspective view of a reduced pressure delivery apparatus according to an embodiment of the present invention, the reduced pressure delivery apparatus having a cellular material attached to a flexible barrier having a spine portion and a pair of wing portions, the cellular material having a plurality of flow channels;

FIG. 7 illustrates a front view of the reduced pressure delivery apparatus ofFIG. 6;

FIG. 8 depicts a cross-sectional side view of the reduced pressure delivery apparatus ofFIG. 7 taken at XVII-XVII;

FIG. 8A illustrates a cross-sectional front view of a reduced pressure delivery apparatus according to an embodiment of the present invention;

FIG. 8B depicts a side view of the reduced pressure delivery apparatus ofFIG. 8A;

FIG. 9 illustrates a front view of a reduced pressure delivery apparatus according to an embodiment of the present invention being used to apply a reduced pressure tissue treatment to a bone of a patient;

FIG. 10 depicts a color histological section of a rabbit cranium showing naive, undamaged bone;

FIG. 11 illustrates a color histological section of a rabbit cranium showing induction of granulation tissue after application of reduced pressure tissue treatment;

FIG. 12 depicts a color histological section of a rabbit cranium showing deposition of new bone following application of reduced pressure tissue treatment;

FIG. 13 illustrates a color histological section of a rabbit cranium showing deposition of new bone following application of reduced pressure tissue treatment;

FIG. 14 depicts a color photograph of a rabbit cranium having two critical size defects formed in the cranium;

FIG. 15 illustrates a color photograph of the rabbit cranium ofFIG. 14 showing a calcium phosphate scaffold inserted within one of the critical size defects and a stainless steel screen overlaying the second of the critical size defects;

FIG. 16 depicts a color photograph of the rabbit cranium ofFIG. 14 showing the application of reduced pressure tissue treatment to the critical size defects;

FIG. 17 illustrates a color histological section of a rabbit cranium following reduced pressure tissue treatment, the histological section showing deposition of new bone within the calcium phosphate scaffold;

FIG. 18 depicts a radiograph of the scaffold-filled, critical size defect ofFIG. 15 following six days of reduced pressure tissue treatment and two weeks post surgery;

FIG. 19 illustrates a radiograph of the scaffold-filled, critical size defect ofFIG. 15 following six days of reduced pressure tissue treatment and twelve weeks post surgery;

FIG. 20 depicts a front view of a reduced pressure delivery system according to an embodiment of the present invention, the reduced pressure delivery system having a manifold delivery tube that is used to percutaneously insert a reduced pressure delivery apparatus to a tissue site;

FIG. 21 illustrates an enlarged front view of the manifold delivery tube ofFIG. 20, the manifold delivery tube containing a reduced pressure delivery apparatus having a flexible barrier and/or a cellular material in a compressed position;

FIG. 22 depicts an enlarged front view of the manifold delivery tube ofFIG. 21, the flexible barrier and/or cellular material of the reduced pressure delivery apparatus being shown in an expanded position after having been pushed from the manifold delivery tube;

FIG. 23 illustrates a front view of a reduced pressure delivery system according to an embodiment of the present invention, the reduced pressure delivery system having a manifold delivery tube that is used to percutaneously insert a reduced pressure delivery apparatus to a tissue site, the reduced pressure delivery apparatus being shown outside of the manifold delivery tube but constrained by an impermeable membrane in a compressed position;

FIG. 24 depicts a front view of the reduced pressure delivery system ofFIG. 23, the reduced pressure delivery apparatus being shown outside of the manifold delivery tube but constrained by an impermeable membrane in a relaxed position;

FIG. 25 illustrates a front view of the reduced pressure delivery system ofFIG. 23, the reduced pressure delivery apparatus being shown outside of the manifold delivery tube but constrained by an impermeable membrane in an expanded position;

FIG. 25A illustrates a front view of the reduced pressure delivery system ofFIG. 23, the reduced pressure delivery apparatus being shown outside of the manifold delivery tube but surrounded by an impermeable membrane in an expanded position

FIG. 26 depicts a front view of a reduced pressure delivery system according to an embodiment of the present invention, the reduced pressure delivery system having a manifold delivery tube that is used to percutaneously insert a reduced pressure delivery apparatus to a tissue site, the reduced pressure delivery apparatus being shown outside of the manifold delivery tube but constrained by an impermeable membrane, having a glue seal;

FIG. 26A depicts a front view of a reduced pressure delivery system according to an embodiment of the present invention;

FIG. 27 illustrates a front view of a reduced pressure delivery system according to an embodiment of the present invention, the reduced pressure delivery system having a manifold delivery tube that is used to percutaneously inject a reduced pressure delivery apparatus to a tissue site;

FIG. 27A illustrates a front view of a reduced pressure delivery system according to an embodiment of the present invention, the reduced pressure delivery system having a manifold delivery tube that is used to percutaneously deliver a reduced pressure delivery apparatus to an impermeable membrane positioned at a tissue site;

FIG. 28 depicts a flow chart of a method of administering a reduced pressure tissue treatment to a tissue site according to an embodiment of the present invention;

FIG. 29 illustrates a flow chart of a method of administering a reduced pressure tissue treatment to a tissue site according to an embodiment of the present invention;

FIG. 30 depicts a flow chart of a method of administering a reduced pressure tissue treatment to a tissue site according to an embodiment of the present invention;

FIG. 31 illustrates a flow chart of a method of administering a reduced pressure tissue treatment to a tissue site according to an embodiment of the present invention;

FIG. 32 depicts a cross-sectional front view of a reduced pressure delivery apparatus according to an embodiment of the present invention, the reduced pressure delivery apparatus including a hip prosthesis having a plurality of flow channels for applying a reduced pressure to an area of bone surrounding the hip prosthesis;

FIG. 33 illustrates a cross-sectional front view of the hip prosthesis ofFIG. 32 having a second plurality of flow channels for delivering a fluid to the area of bone surrounding the hip prosthesis;

FIG. 34 depicts a flow chart of a method for repairing a joint of a patient using reduced pressure tissue treatment according to an embodiment of the present invention;

FIG. 35 illustrates a cross-sectional front view of a reduced pressure delivery apparatus according to an embodiment of the present invention, the reduced pressure delivery apparatus including a orthopedic fixation device having a plurality of flow channels for applying a reduced pressure to an area of bone adjacent the orthopedic fixation device;

FIG. 36 depicts a cross-sectional front view of the orthopedic fixation device ofFIG. 35 having a second plurality of flow channels for delivering a fluid to the area of bone adjacent the orthopedic fixation device;

FIG. 37 illustrates a flow chart of a method for healing a bone defect of a bone using reduced pressure tissue treatment according to an embodiment of the present invention;

FIG. 38 depicts a flow chart of a method of administering a reduced pressure tissue treatment to a tissue site according to an embodiment of the present invention; and

FIG. 39 illustrates a flow chart of a method of administering a reduced pressure tissue treatment to a tissue site according to an embodiment of the present invention.

FIGS. 40-48 depict various views of a reduced pressure delivery system according to an embodiment of the present invention, the reduced pressure delivery system having a primary manifold that includes a flexible wall surrounding a primary flow passage and a plurality of apertures in the flexible wall;

FIGS. 49-50 illustrate perspective and top cross-sectional views of a reduced pressure delivery system according to an embodiment of the present invention, the reduced pressure delivery system having a primary manifold that is integrally connected to a reduced pressure delivery tube;

FIG. 51 depicts a perspective view of the primary manifolds ofFIGS. 40-50 being applied with a secondary manifold to a bone tissue site; and

FIG. 52 illustrates a schematic view of a reduced pressure delivery system having a valve fluidly connected to a second conduit according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific preferred embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is understood that other embodiments may be utilized and that logical structural, mechanical, electrical, and chemical changes may be, made without departing from the spirit or scope of the invention. To avoid detail not necessary to enable those skilled in the art to practice the invention, the description may omit certain information known to those skilled in the art. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims.

As used herein, the term “elastomeric” means having the properties of an elastomer. The term “elastomer” refers generally to a polymeric material that has rubber-like properties. More specifically, most elastomers have elongation rates greater than 100% and a significant amount of resilience. The resilience of a material refers to the material's ability to recover from an elastic deformation. Examples of elastomers may include, but are not limited to, natural rubbers, polyisoprene, styrene butadiene rubber, chloroprene rubber, polybutadiene, nitrile rubber, butyl rubber, ethylene propylene rubber, ethylene propylene diene monomer, chlorosulfonated polyethylene, polysulfide rubber, polyurethane, and silicones.

As used herein, the term “flexible” refers to an object or material that is able to be bent or flexed. Elastomeric materials are typically flexible, but reference to flexible materials herein does not necessarily limit material selection to only elastomers. The use of the term “flexible” in connection with a material or reduced pressure delivery apparatus of the present invention generally refers to the material's ability to conform to or closely match the shape of a tissue site. For example, the flexible nature of a reduced pressure delivery apparatus used to treat a bone defect may allow the apparatus to be wrapped or folded around the portion of the bone having the defect.

The term “fluid” as used herein generally refers to a gas or liquid, but may also include any other flowable material, including but not limited to gels, colloids, and foams.

The term “impermeable” as used herein generally refers to the ability of a membrane, cover, sheet, or other substance to block or slow the transmission of either liquids or gas. Impermeability may be used to refer to covers, sheets, or other membranes that are resistant to the transmission of liquids, while allowing gases to transmit through the membrane. While an impermeable membrane may be liquid tight, the membrane may simply reduce the transmission rate of all or only certain liquids. The use of the term “impermeable” is not meant to imply that an impermeable membrane is above or below any particular industry standard measurement for impermeability, such as a particular value of water vapor transfer rate (WVTR).

The term “manifold” as used herein generally refers to a substance or structure that is provided to assist in applying reduced pressure to, delivering fluids to, or removing fluids from a tissue site. A manifold typically includes a plurality of flow channels or pathways that are interconnected to improve distribution of fluids provided to and removed from the area of tissue around the manifold. Examples of manifolds may include without limitation devices that have structural elements arranged to form flow channels, cellular foam such as open-cell foam, porous tissue collections, and liquids, gels and foams that include or cure to include flow channels.

The term “reduced pressure” as used herein generally refers to a pressure less than the ambient pressure at a tissue site that is being subjected to treatment. In most cases, this reduced pressure will be less than the atmospheric pressure at which the patient is located. Alternatively, the reduced pressure may be less than a hydrostatic pressure of tissue at the tissue site. Although the terms “vacuum” and “negative pressure” may be used to describe the pressure applied to the tissue site, the actual pressure applied to the tissue site may be significantly less than the pressure normally associated with a complete vacuum. Reduced pressure may initially generate fluid flow in the tube and the area of the tissue site. As the hydrostatic pressure around the tissue site approaches the desired reduced pressure, the flow may subside, and the reduced pressure is then maintained. Unless otherwise indicated, values of pressure stated herein are gage pressures.

The term “scaffold” as used herein refers to a substance or structure used to enhance or promote the growth of cells and/or the formation of tissue. A scaffold is typically a three dimensional porous structure that provides a template for cell growth. The scaffold may be infused with, coated with, or comprised of cells, growth factors, or other nutrients to promote cell growth. A scaffold may be used as a manifold in accordance with the embodiments described herein to administer reduced pressure tissue treatment to a tissue site.

The term “tissue site” as used herein refers to a wound or defect located on or within any tissue, including but not limited to, bone tissue, adipose tissue, muscle tissue, neural tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, or ligaments. The term “tissue site” may further refer to areas of any tissue that are not necessarily wounded or defective, but are instead areas in which it is desired to add or promote the growth of additional tissue. For example, reduced pressure tissue treatment may be used in certain tissue areas to grow additional tissue that may be harvested and transplanted to another tissue location.

Referring toFIGS. 1-5, a reduced pressure delivery apparatus, orwing manifold211 according to the principles of the present invention includes aflexible barrier213 having aspine portion215 and a pair ofwing portions219. Eachwing portion219 is positioned along opposite sides of thespine portion215. Thespine portion215 forms anarcuate channel223 that may or may not extend the entire length of thewing manifold211. Although thespine portion215 may be centrally located on thewing manifold211 such that the width of thewing portions219 is equal, thespine portion215 may also be offset as illustrated inFIGS. 1-5, resulting in one of thewing portions219 being wider than theother wing portion219. The extra width of one of thewing portions219 may be particularly useful if thewing manifold211 is being used in connection with bone regeneration or healing and thewider wing manifold211 is to be wrapped around fixation hardware attached to the bone.

Theflexible barrier213 is preferably formed by an elastomeric material such as a silicone polymer. An example of a suitable silicone polymer includes MED-6015 manufactured by Nusil Technologies of Carpinteria, Calif. It should be noted, however, that theflexible barrier213 could be made from any other biocompatible, flexible material. Theflexible barrier213 encases aflexible backing227 that adds strength and durability to theflexible barrier213. The thickness of theflexible barrier213 encasing theflexible backing227 may be less in thearcuate channel223 than that in thewing portions219. If a silicone polymer is used to form theflexible barrier213, a silicone adhesive may also be used to aid bonding with theflexible backing227. An example of a silicone adhesive could include MED-1011, also sold by Nusil Technologies. Theflexible backing227 is preferably made from a polyester knit fabric such as Bard 6013 manufactured by C. R. Bard of Tempe, Ariz. However, theflexible backing227 could be made from any biocompatible, flexible material that is capable of adding strength and durability to theflexible barrier213. Under certain circumstances, if theflexible barrier213 is made from a suitably strong material, theflexible backing227 could be omitted.

It is preferred that either theflexible barrier213 or theflexible backing227 be impermeable to liquids, air, and other gases, or alternatively, both theflexible backing227 and theflexible barrier213 may be impermeable to liquids, air, and other gases.

Theflexible barrier213 andflexible backing227 may also be constructed from bioresorbable materials that do not have to be removed from a patient's body following use of the reducedpressure delivery apparatus211. Suitable bioresorbable materials may include, without limitation, a polymeric blend of polylactic acid (PLA) and polyglycolic acid (PGA). The polymeric blend may also include without limitation polycarbonates, polyfumarates, and capralactones. Theflexible barrier213 and theflexible backing227 may further serve as a scaffold for new cell-growth, or a scaffold material may be used in conjunction with theflexible barrier213 andflexible backing227 to promote cell-growth. Suitable scaffold material may include, without limitation, calcium phosphate, collagen, PLA/PGA, coral hydroxy apatites, carbonates, or processed allograft materials. Preferably, the scaffold material will have a high void-fraction (i.e. a high content of air).

In one embodiment theflexible backing227 may be adhesively attached to a surface of theflexible barrier213. If a silicone polymer is used to form theflexible barrier213, a silicone adhesive may also be used to attach theflexible backing227 to theflexible barrier213. While an adhesive is the preferred method of attachment when theflexible backing227 is surface bonded to theflexible barrier213, any suitable attachment may be used.

Theflexible barrier213 includes a plurality ofprojections231 extending from thewing portions219 on a surface of theflexible barrier213. Theprojections231 may be cylindrical, spherical, hemispherical, cubed, or any other shape, as long as at least some portion of eachprojection231 is in a plane different than the plane associated with the side of theflexible backing213 to which theprojections231 are attached. In this regard, aparticular projection231 is not even required to have the same shape or size asother projections231; in fact, theprojections231 may include a random mix of different shapes and sizes. Consequently, the distance by which eachprojection231 extends from theflexible barrier213 could vary, but may also be uniform among the plurality ofprojections231.

The placement ofprojections231 on theflexible barrier213 creates a plurality offlow channels233 between the projections. When theprojections231 are of uniform shape and size and are spaced uniformly on theflexible barrier213, theflow channels233 created between theprojections231 are similarly uniform. Variations in the size, shape, and spacing of theprojections231 may be used to alter the size and flow characteristics of theflow channels233.

A reduced-pressure delivery tube241 is positioned within thearcuate channel223 and is attached to theflexible barrier213 as illustrated inFIG. 5. The reduced-pressure delivery tube241 may be attached solely to theflexible barrier213 or theflexible backing227, or thetube241 could be attached to both theflexible barrier213 and theflexible backing227. The reduced-pressure delivery tube241 includes adistal orifice243 at a distal end of thetube241. Thetube241 may be positioned such that thedistal orifice243 is located at any point along thearcuate channel223, but thetube241 is preferably positioned such that thedistal orifice243 is located approximately midway along the longitudinal length of thearcuate channel223. Thedistal orifice243 is preferably made elliptical or oval in shape by cutting thetube241 along a plane that is oriented less than ninety (90) degrees to the longitudinal axis of thetube241. While theorifice243 may also be round, the elliptical shape of theorifice243 increases fluid communication with theflow channels233 formed between theprojections231.

The reduced-pressure delivery tube241 is preferably made from paralyne-coated silicone or urethane. However, any medical-grade tubing material may be used to construct the reduced-pressure delivery tube241. Other coatings that may coat the tube include heparin, anti-coagulants, anti-fibrinogens, anti-adherents, anti-thrombinogens, and hydrophilic coatings.

In one embodiment, the reduced-pressure delivery tube241 may also include vent openings, or ventorifices251 positioned along the reduced-pressure delivery tube241 as either an alternative to thedistal orifice243 or in addition to thedistal orifice243 to further increase fluid communication between the reduced-pressure delivery tube241 and theflow channels233. The reduced-pressure delivery tube241 may be positioned along only a portion of the longitudinal length of thearcuate channel223 as shown inFIGS. 1-5, or alternatively may be positioned along the entire longitudinal length of thearcuate channel223. If positioned such that the reduced-pressure delivery tube241 occupies the entire length of thearcuate channel223, thedistal orifice243 may be capped such that all fluid communication between thetube241 and theflow channels233 occurs through thevent openings251.

The reduced-pressure delivery tube241 further includes aproximal orifice255 at a proximal end of thetube241. Theproximal orifice255 is configured to mate with a reduced-pressure source, which is described in more detail below with reference toFIG. 9. The reduced-pressure delivery tube241 illustrated inFIGS. 1-3,4A, and5 includes only a single lumen, orpassageway259. It is possible, however, for the reduced-pressure delivery tube241 to include multiple lumens such as adual lumen tube261 illustrated inFIG. 4B. Thedual lumen tube261 includes afirst lumen263 and asecond lumen265. The use of a dual lumen tube provides separate paths of fluid communication between the proximal end of the reduced-pressure delivery tube241 and theflow channels233. For example, the use of thedual lumen tube261 may be used to allow communication between the reduced pressure source and theflow channels233 along thefirst lumen263. Thesecond lumen265 may be used to introduce a fluid to theflow channels233. The fluid may be filtered air or other gases, antibacterial agents, antiviral agents, cell-growth promotion agents, irrigation fluids, chemically active fluids, or any other fluid. If it is desired to introduce multiple fluids to theflow channels233 through separate fluid communication paths, a reduced-pressure delivery tube may be provided with more than two lumens.

Referring still toFIG. 4B, ahorizontal divider271 separates the first and

second lumens

263,265 of the reduced-pressure delivery tube261, resulting in thefirst lumen263 being positioned above thesecond lumen265. The relative position of the first and

second lumens

263,265 may vary, depending on how fluid communication is provided between the

lumens

263,265 and theflow channels233. For example, when thefirst lumen263 is positioned as illustrated inFIG. 4B, vent openings similar to ventopenings251 may be provided to allow communication with theflow channels233. When thesecond lumen263 is positioned as illustrated inFIG. 4B, thesecond lumen263 may communicate with theflow channels233 through a distal orifice similar todistal orifice243. Alternatively, the multiple lumens of a reduced-pressure delivery tube could be positioned side by side with a vertical divider separating the lumens, or the lumens could be arranged concentrically or coaxially.

It should be apparent to a person having ordinary skill in the art that the provision of independent paths of fluid communication could be accomplished in a number of different ways, including that of providing a multi-lumen tube as described above. Alternatively, independent paths of fluid communication may be provided by attaching a single lumen tube to another single lumen tube, or by using separate, unattached tubes with single or multiple lumens.

If separate tubes are used to provide separate paths of fluid communication to theflow channels233, thespine portion215 may include multiplearcuate channels223, one for each tube. Alternatively thearcuate channel223 may be enlarged to accommodate multiple tubes. An example of a reduced-pressure delivery apparatus having a reduced-pressure delivery tube separate from a fluid delivery tube is discussed in more detail below with reference toFIG. 9.

Referring toFIGS. 6-8, a reduced pressure delivery apparatus, orwing manifold311 according to the principles of the present invention includes aflexible barrier313 having aspine portion315 and a pair ofwing portions319. Eachwing portion319 is positioned along opposite sides of thespine portion315. Thespine portion315 forms anarcuate channel323 that may or may not extend the entire length of thewing manifold311. Although thespine portion315 may be centrally located on thewing manifold311 such that the size of thewing portions319 is equal, thespine portion315 may also be offset as illustrated inFIGS. 6-8, resulting in one of thewing portions319 being wider than theother wing portion319. The extra width of one of thewing portions319 may be particularly useful if thewing manifold311 is being used in connection with bone regeneration or healing and thewider wing manifold311 is to be wrapped around fixation hardware attached to the bone.

Acellular material327 is attached to theflexible barrier313 and may be provided as a single piece of material that covers the entire surface of theflexible barrier313, extending across thespine portion315 and bothwing portions319. Thecellular material327 includes an attachment surface (not visible inFIG. 6) that is disposed adjacent to theflexible barrier313, amain distribution surface329 opposite the attachment surface, and a plurality of perimeter surfaces330.

In one embodiment theflexible barrier313 may be similar toflexible barrier213 and include a flexible backing. While an adhesive is a preferred method of attaching thecellular material327 to theflexible barrier313, theflexible barrier313 andcellular material327 could be attached by any other suitable attachment method or left for the user to assemble at the site of treatment. Theflexible barrier313 and/or flexible backing serve as an impermeable barrier to transmission of fluids such as liquids, air, and other gases.

In one embodiment, a flexible barrier and flexible backing may not be separately provided to back thecellular material327. Rather, thecellular material327 may have an integral barrier layer that is an impermeable portion of thecellular material327. The barrier layer could be formed from closed-cell material to prevent transmission of fluids, thereby substituting for theflexible barrier313. If an integral barrier layer is used with thecellular material327, the barrier layer may include a spine portion and wing portions as described previously with reference to theflexible barrier313.

Theflexible barrier313 is preferably made from an elastomeric material such as a silicone polymer. An example of a suitable silicone polymer includes MED-6015 manufactured by Nusil Technologies of Carpinteria, Calif. It should be noted, however, that theflexible barrier313 could be made from any other biocompatible, flexible material. If the flexible barrier encases or otherwise incorporates a flexible backing, the flexible backing is preferably made from a polyester knit fabric such as Bard 6013 manufactured by C. R. Bard of Tempe, Ariz. However, theflexible backing227 could be made from any biocompatible, flexible material that is capable of adding strength and durability to theflexible barrier313.

In one embodiment, thecellular material327 is an open-cell, reticulated polyetherurethane foam with pore sizes ranging from about 400-600 microns. An example of this foam may include GranuFoam manufactured by Kinetic Concepts, Inc. of San Antonio, Tex. Thecellular material327 may also be gauze, felted mats, or any other biocompatible material that provides fluid communication through a plurality of channels in three dimensions.

Thecellular material327 is primarily an “open cell” material that includes a plurality of cells fluidly connected to adjacent cells. A plurality of flow channels is formed by and between the “open cells” of thecellular material327. The flow channels allow fluid communication throughout that portion of thecellular material327 having open cells. The cells and flow channels may be uniform in shape and size, or may include patterned or random variations in shape and size. Variations in shape and size of the cells of thecellular material327 result in variations in the flow channels, and such characteristics can be used to alter the flow characteristics of fluid through thecellular material327. Thecellular material327 may further include portions that include “closed cells.” These closed-cell portions of thecellular material327 contain a plurality of cells, the majority of which are not fluidly connected to adjacent cells. An example of a closed-cell portion is described above as a barrier layer that may be substituted for theflexible barrier313. Similarly, closed-cell portions could be selectively disposed in thecellular material327 to prevent transmission of fluids through the perimeter surfaces330 of thecellular material327.

Theflexible barrier313 andcellular material327 may also be constructed from bioresorbable materials that do not have to be removed from a patient's body following use of the reducedpressure delivery apparatus311. Suitable bioresorbable materials may include, without limitation, a polymeric blend of polylactic acid (PLA) and polyglycolic acid (PGA). The polymeric blend may also include without limitation polycarbonates, polyfumarates, and capralactones. Theflexible barrier313 and thecellular material327 may further serve as a scaffold for new cell-growth, or a scaffold material may be used in conjunction with theflexible barrier313,flexible backing327, and/orcellular material327 to promote cell-growth. Suitable scaffold materials may include, without limitation, calcium phosphate, collagen, PLA/PGA, coral hydroxy apatites, carbonates, or processed allograft materials. Preferably, the scaffold material will have a high void-fraction (i.e. a high content of air).

A reduced-pressure delivery tube341′ is positioned within thearcuate channel323 and is attached to theflexible barrier313. The reduced-pressure delivery tube341 may also be attached to thecellular material327, or in the case of only acellular material327 being present, the reduced-pressure delivery tube341 may be attached to only thecellular material327. The reduced-pressure delivery tube341 includes adistal orifice343 at a distal end of thetube341 similar to thedistal orifice243 ofFIG. 5. The reduced-pressure delivery tube341 may be positioned such that thedistal orifice343 is located at any point along thearcuate channel323, but is preferably located approximately midway along the longitudinal length of thearcuate channel323. Thedistal orifice343 is preferably made elliptical or oval in shape by cutting thetube341 along a plane that is oriented less than ninety (90) degrees to the longitudinal axis of thetube341. While the orifice may also be round, the elliptical shape of the orifice increases fluid communication with the flow channels in thecellular material327.

In one embodiment, the reduced-pressure delivery tube341 may also include vent openings, or vent orifices (not shown) similar to ventopenings251 ofFIG. 5. The vent openings are positioned along thetube341 as either an alternative to thedistal orifice343 or in addition to thedistal orifice343 to further increase fluid communication between the reduced-pressure delivery tube341 and the flow channels. As previously described, the reduced-pressure delivery tube341 may be positioned along only a portion of the longitudinal length of thearcuate channel323, or alternatively may be positioned along the entire longitudinal length of thearcuate channel323. If positioned such that the reduced-pressure delivery tube341 occupies the entirearcuate channel323, thedistal orifice343 may be capped such that all fluid communication between thetube341 and the flow channels occurs through the vent openings.

Preferably, thecellular material327 overlays and directly contacts the reduced-pressure delivery tube341. Thecellular material327 may be connected to the reduced-pressure delivery tube341, or thecellular material327 may simply be attached to theflexible barrier313. If the reduced-pressure delivery tube341 is positioned such that it only extends to a midpoint of thearcuate channel323, thecellular material327 may also be connected to thespine portion315 of theflexible barrier313 in that area of thearcuate channel323 that does not contain the reduced-pressure delivery tube341.

The reduced-pressure delivery tube341 further includes aproximal orifice355 at a proximal end of thetube341. Theproximal orifice355 is configured to mate with a reduced-pressure source, which is described in more detail below with reference toFIG. 9. The reduced-pressure delivery tube341 illustrated inFIGS. 6-8 includes only a single lumen, orpassageway359. It is possible, however, for the reduced-pressure delivery tube341 to include multiple lumens such as those described previously with reference toFIG. 4B. The use of a multiple lumen tube provides separate paths of fluid communication between the proximal end of the reduced-pressure delivery tube341 and the flow channels as previously described. These separate paths of fluid communication may also be provided by separate tubes having single or multiple lumens that communicate with the flow channels.

Referring toFIG. 9, a reducedpressure delivery apparatus411 similar to the other reduced pressure delivery apparatuses described herein is used to apply a reduced pressure tissue treatment to atissue site413, such as a human bone415 of a patient. When used to promote bone tissue growth, reduced pressure tissue treatment can increase the rate of healing associated with a fracture, a non-union, a void, or other bone defects. It is further believed that reduced pressure tissue treatment may be used to improve recovery from osteomyelitis. The therapy may further be used to increase localized bone densities in patients suffering from osteoporosis. Finally, reduced pressure tissue treatment may be used to speed and improve oseointegration of orthopedic implants such as hip implants, knee implants, and fixation devices.

Referring still toFIG. 9, the reducedpressure delivery apparatus411 includes a reduced-pressure delivery tube419 having aproximal end421 fluidly connected to a reducedpressure source427. The reducedpressure source427 is a pump or any other device that is capable of applying a reduced pressure to thetissue site413 through the reducedpressure delivery tube419 and a plurality of flow channels associated with the reducedpressure delivery apparatus411. Applying reduced pressure to thetissue site413 is accomplished by placing the wing portions of the reducedpressure delivery apparatus411 adjacent thetissue site413, which in this particular example involves wrapping the wing portions around avoid defect429 in the bone415. The reduced pressure delivery apparatus'411 may be surgically or percutaneously inserted. When percutaneously inserted, the reduced-pressure delivery tube419 is preferably inserted through a sterile insertion sheath that penetrates the skin tissue of the patient.

The application of reduced pressure tissue treatment typically generates granulation tissue in the area surrounding thetissue site413. Granulation tissue is a common tissue that often forms prior to tissue repair in the body. Under normal circumstances, granulation tissue may form in response to a foreign body or during wound healing. Granulation tissue typically serves as a scaffold for healthy replacement tissue and further results in the development of some scar tissue. Granulation tissue is highly vascularized, and the increased growth and growth rate of the highly vascularized tissue in the presence of reduced pressure promotes new tissue growth at thetissue site413.

Referring still toFIG. 9, afluid delivery tube431 may be fluidly connected at a distal end to the flow channels of the reducedpressure delivery apparatus411. Thefluid delivery tube431 includes aproximal end432 that is fluidly connected to afluid delivery source433. If the fluid being delivered to the tissue site is air, the air is preferably filtered by afilter434 capable of filtering particles at least as small as 0.22 μm in order to clean and sterilize the air. The introduction of air to thetissue site413, especially when thetissue site413 is located beneath the surface of the skin, is important to facilitate good drainage of thetissue site413, thereby reducing or preventing obstruction of the reducedpressure delivery tube419. Thefluid delivery tube431 andfluid delivery source433 could also be used to introduce other fluids to thetissue site413, including without limitation an antibacterial agent, an antiviral agent, a cell-growth promotion agent, an irrigation fluid, or other chemically active agents. When percutaneously inserted, thefluid delivery tube431 is preferably inserted through a sterile insertion sheath that penetrates the skin tissue of the patient.

Apressure sensor435 may be operably connected to thefluid delivery tube431 to indicate whether thefluid delivery tube431 is occluded with blood or other bodily fluids. Thepressure sensor435 may be operably connected to thefluid delivery source433 to provide feedback so that the amount of fluid introduced to thetissue site413 is controlled. A check valve (not shown) may also be operably connected near the distal end of thefluid delivery tube431 to prevent blood or other bodily fluids from entering thefluid delivery tube431.

The independent paths of fluid communication provided by reducedpressure delivery tube419 and fluid delivery tube4131 may be accomplished in a number of different ways, including that of providing a single, multi-lumen tube as described previously with reference toFIG. 4B. A person of ordinary skill in the art will recognize that the sensors, valves, and other components associated with thefluid delivery tube431 could also be similarly associated with a particular lumen in the reducedpressure delivery tube419 if a multi-lumen tube is used. It is preferred that any lumen or tube that fluidly communicates with the tissue site be coated with an anti-coagulent to prevent a build-up of bodily fluids or blood within the lumen or tube. Other coatings that may coat the lumens or tubes include without limitation heparin, anti-coagulants, anti-fibrinogens, anti-adherents, anti-thrombinogens, and hydrophilic coatings.

Referring toFIGS. 10-19, testing has shown the positive effects of reduced pressure tissue treatment when applied to bone tissue. In one particular test, reduced pressure tissue treatment was applied to the cranium of several rabbits to determine its effect on bone growth and regeneration. The specific goals of the test were to discover the effect of reduced pressure tissue treatment on rabbits having no defect on or injury to the cranium, the effect of reduced pressure tissue treatment on rabbits having critical-size defects on the cranium, and the effect of using a scaffold material with reduced pressure tissue treatment to treat critical-size defects on the cranium. The specific testing protocol and number of rabbits are listed below in Table 1.

TABLE 1


Testing Protocol

No. of Rabbits	Protocol

4	No defect on cranium; reduced pressure tissue treatment (RPTT) applied
	through cellular foam (GranuFoam) on top of intact periosteum for 6 days
	followed by immediate tissue harvest
4	No defect on cranium; cellular foam (GranuFoam) placed on top of intact
	periosteum without RPTT (control) for 6 days followed by immediate tissue
	harvest
4	One critical-size defect with stainless-steel screen placed on defect; one
	critical-size defect with calcium phosphate scaffold placed in defect; 24 hours
	RPTT applied to both defects; tissue harvest 2 weeks post-surgery
4	One critical-size defect with stainless-steel screen placed on defect; one
	critical-size defect with calcium phosphate scaffold placed in defect; 24 hours
	RPTT applied to both defects; tissue harvest 12 weeks post-surgery
4	One critical-size defect with stainless-steel screen placed on defect; one
	critical-size defect with calcium phosphate scaffold placed in defect; 6 days
	RPTT applied to both defects; tissue harvest 2 weeks post-surgery
4	One critical-size defect with stainless-steel screen placed on defect; one
	critical-size defect with calcium phosphate scaffold placed in defect; 6 days
	RPTT applied to both defects; tissue harvest 12 weeks post-surgery
4	One critical-size defect with stainless-steel screen placed on defect; one
	critical-size defect with calcium phosphate scaffold placed in defect; no RPTT
	applied (control); tissue harvest 2 weeks post-surgery
4	One critical-size defect with stainless-steel screen placed on defect; one
	critical-size defect with calcium phosphate scaffold placed in defect; no RPTT
	applied (control); tissue harvest 12 weeks post-surgery
4	Native control (no surgery; no RPTT)
4	Sham surgery (no defects, no RPTT); tissue harvest 6 days post-surgery

Critical-size defects are defects in a tissue (e.g. the cranium), the size of which is large enough that the defect will not heal solely by in-life recovery. For rabbits, boring a full-thickness hole through the cranium that is approximately 15 mm in diameter creates a critical-size defect of the cranium.

Referring more specifically toFIG. 10, a histological section of a rabbit cranium having naïve, undamaged bone is illustrated. The bone tissue of the cranium is colored magenta, the surrounding soft tissue white, and the layer of periosteum is highlighted by yellow asterisks. InFIG. 11, the rabbit cranium is illustrated following the application of reduced pressure tissue treatment for 6 days followed by immediate tissue harvest. The bone and periosteum are visible, and a layer of granulation tissue has developed. InFIG. 12, the rabbit cranium is illustrated following the application of reduced pressure tissue treatment for 6 days and followed by immediate tissue harvest. The histological section ofFIG. 12 is characterized by the development of new bone tissue underlying the granulation tissue. The bone tissue is highlighted by yellow asterisks. InFIG. 13, the rabbit cranium is illustrated following the application of reduced pressure tissue treatment for 6 days followed by immediate tissue harvest. The new bone and periosteum are visible. This histological appearance of bone tissue development in response to reduced pressure tissue treatment is very similar to the histological appearance of bone development in a very young animal that is undergoing very rapid growth and deposition of new bone.

Referring more specifically toFIGS. 14-19, several photographs and histological sections are illustrated showing the procedures and results of reduced pressure tissue treatment on a rabbit cranium having critical-size defects. InFIG. 14, a rabbit cranium is illustrated on which two critical-size defects have been created. The full-thickness critical-size defects are approximately 15 mm in diameter. InFIG. 15, a stainless-steel screen has been placed over one of the critical-size defects, and a calcium phosphate scaffold has been placed within the second critical-size defect. InFIG. 16, a reduced pressure tissue treatment apparatus similar to those described herein is used to apply reduced pressure to the critical-size defects. The amount of pressure applied to each defect was −125 mm Hg gauge pressure. The reduced pressure was applied according to one of the protocols listed in Table 1. InFIG. 17, a histological section of cranium following six-day reduced pressure tissue treatment and twelve week post-surgery harvest is illustrated. The section illustrated includes calcium phosphate scaffold, which is indicated by red arrows. The application of reduced pressure tissue treatment resulted in the significant growth of new bone tissue, which is highlighted inFIG. 17 by yellow asterisks. The amount of bone growth is significantly greater than in critical-size defects containing identical calcium phosphate scaffolds but which were not treated with reduced pressure tissue treatment. This observation suggests there may be a threshold level or duration of therapy required to elicit a prolific new-bone response. Effects of reduced pressure tissue treatment are most pronounced in the specimens collected 12 weeks post-surgery, indicating the reduced pressure tissue treatment initiates a cascade of biological events leading to enhanced formation of new bone tissue.

Critical-size defects covered with stainless steel screens (FIG. 15) but without scaffold material in the defect served as intra-animal controls with minimal new-bone growth. These data highlight the advantage of an appropriate scaffold material and the positive effect of reduced pressure tissue treatment on scaffold integration and biological performance. InFIGS. 18 and 19, radiographs of scaffold-filled, critical-size defects are illustrated following six days of reduced pressure tissue treatment.FIG. 18 illustrates the defect two weeks post-surgery and indicates some new bone deposition within the scaffold. The primary structure of the scaffold is still evident.FIG. 19 illustrates the defect twelve weeks post surgery and shows almost complete healing of the critical-size defect and a near complete loss of the primary scaffold architecture due to tissue integration, i.e. new bone formation within the scaffold matrix.

Referring toFIG. 20, a reducedpressure delivery system711 according to an embodiment of the present invention delivers reduced pressure tissue treatment to atissue site713 of a patient. The reducedpressure delivery system711 includes amanifold delivery tube721. Themanifold delivery tube721 may be a catheter or cannula and may include features such as asteering unit725 and aguide wire727 that allow themanifold delivery tube721 to be guided to thetissue site713. Placement and direction of theguide wire727 and themanifold delivery tube721 may be accomplished by using endoscopy, ultrasound, fluoroscopy, auscultation, palpation, or any other suitable localization technique. Themanifold delivery tube721 is provided to percutaneously insert a reduced pressure delivery apparatus to thetissue site713 of the patient. When percutaneously inserted, themanifold delivery tube721 is preferably inserted through a sterile insertion sheath that penetrates the skin tissue of the patient.

InFIG. 20, thetissue site713 includes bone tissue adjacent afracture731 on abone733 of the patient. Themanifold delivery tube721 is inserted through the patient'sskin735 and anysoft tissue739 surrounding thebone733. As previously discussed, thetissue site713 may also include any other type of tissue, including without limitation adipose tissue, muscle tissue, neural tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, or ligaments.

Referring toFIGS. 21 and 22, the reducedpressure delivery system711 is further illustrated. Themanifold delivery tube721 may include a tapereddistal end743 to ease insertion through the patient'sskin735 andsoft tissue739. The tapereddistal end743 may further be configured to flex radially outward to an open position such that the inner diameter of thedistal end743 would be substantially the same as or greater than the inner diameter at other portions of thetube721. The open position of thedistal end743 is schematically illustrated inFIG. 21 bybroken lines737.

Themanifold delivery tube721 further includes apassageway751 in which a reducedpressure delivery apparatus761, or any other reduced pressure delivery apparatus, is contained. The reducedpressure delivery apparatus761 includes aflexible barrier765 and/orcellular material767 similar to that described with reference toFIGS. 6-8. Theflexible barrier765 and/orcellular material767 is preferably rolled, folded, or otherwise compressed around a reducedpressure delivery tube769 to reduce the cross-sectional area of the reducedpressure delivery apparatus761 within thepassageway751.

The reducedpressure delivery apparatus761 may be placed within thepassageway751 and guided to thetissue site713 following the placement of thedistal end743

manifold delivery tube

Referring toFIGS. 23-25, a reducedpressure delivery system811 according to an embodiment of the present invention includes amanifold delivery tube821 having a tapereddistal end843 that is configured to flex radially outward to an open position such that the inner diameter of thedistal end843 would be substantially the same as or greater than the inner diameter at other portions of thetube821. The open position of thedistal end843 is schematically illustrated inFIGS. 23-25 bybroken lines837.

Themanifold delivery tube821 further includes a passageway in which a reducedpressure delivery apparatus861 similar to the other reduced pressure delivery apparatuses described herein is contained. The reducedpressure delivery apparatus861 includes aflexible barrier865 and/or acellular material867 that is preferably rolled, folded, or otherwise compressed around a reducedpressure delivery tube869 to reduce the cross-sectional area of the reducedpressure delivery apparatus861 within the passageway.

Animpermeable membrane871 having aninner space873 is disposed around the reducedpressure delivery apparatus861 such that the reducedpressure delivery apparatus861 is contained within theinner space873 of theimpermeable membrane871. Theimpermeable membrane871 may be a balloon, a sheath, or any other type of membrane that is capable of preventing fluid transmission such that theimpermeable membrane871 can assume at least one of a compressed position (seeFIG. 23), a relaxed position (seeFIG. 24), and an expanded position (seeFIGS. 25 and 25A). Theimpermeable membrane871 may be sealingly connected to themanifold delivery tube821 such that theinner space873 of theimpermeable membrane871 is in fluid communication with the passageway of themanifold delivery tube821. Theimpermeable membrane871 may alternatively be attached to the reducedpressure delivery tube869 such that theinner space873 of theimpermeable membrane871 is in fluid communication with the passageway of the reducedpressure delivery tube869. Theimpermeable membrane871 instead may be attached to a separate control tube or control lumen (see for exampleFIG. 25A) that fluidly communicates with theinner space873.

Referring toFIG. 25A, if theimpermeable membrane871 is used primarily to dissect tissue adjacent the tissue site, theimpermeable membrane871 may be sealingly attached to themanifold delivery tube821 such that theinner space873 fluidly communicates with a secondary lumen ortube891 associated with or attached to themanifold delivery tube821. Thesecondary lumen891 may be used to deliver a liquid, air, or other fluid to theinner space873 to place theimpermeable membrane871 in the expanded position. Following dissection, theimpermeable membrane871 may be relaxed and ruptured as previously described with reference toFIG. 24.

Referring toFIG. 26, a reducedpressure delivery system911 according to an embodiment of the present invention includes amanifold delivery tube921 having a tapereddistal end943 that is configured to flex radially outward to an open position such that the inner diameter of thedistal end943 would be substantially the same as or greater than the inner diameter at other portions of thetube921. The open position of thedistal end943 is schematically illustrated inFIG. 26 bybroken lines937.

Themanifold delivery tube921 further includes a passageway in which a reducedpressure delivery apparatus961 similar to the other reduced pressure delivery apparatuses described herein is contained. The reducedpressure delivery apparatus961 includes aflexible barrier965 and/or acellular material967 that is preferably rolled, folded, or otherwise compressed around a reducedpressure delivery tube969 to reduce the cross-sectional area of the reducedpressure delivery apparatus961 within the passageway of themanifold delivery tube921.

Animpermeable membrane971 having aninner space973 is disposed around the reducedpressure delivery apparatus961 such that the reducedpressure delivery apparatus961 is contained within theinner space973 of theimpermeable membrane971. Theimpermeable membrane971 includes aglue seal977 on one end of theimpermeable membrane971 to provide an alternative method of removing the reducedpressure delivery apparatus961 from theimpermeable membrane971. Theimpermeable membrane971 may be sealingly connected at another end to themanifold delivery tube921 such that theinner space973 of theimpermeable membrane971 is in fluid communication with the passageway of themanifold delivery tube921. Alternatively, theimpermeable membrane971 may be attached to a separate control tube (not shown) that fluidly communicates with theinner space973.

The reducedpressure delivery apparatus961 is delivered to the tissue site within theimpermeable membrane971 and then properly positioned using endoscopy, ultrasound, fluoroscopy, auscultation, palpation, or any other suitable localization technique. Theimpermeable membrane971 may include radioopaque markers981 that improve visualization of theimpermeable membrane971 under fluoroscopy prior to its removal. The reducedpressure delivery apparatus961 is then pushed through thedistal end943 of themanifold delivery tube921. The reduced pressure applied to theinner space973 may be eased to place theimpermeable membrane971 in the relaxed position. The reducedpressure delivery apparatus961 is then pushed through theglue seal977 to exit theimpermeable membrane971.

Referring toFIG. 27, a reducedpressure delivery system1011 according to an embodiment of the present invention includes amanifold delivery tube1021 having adistal end1043 that is inserted through a tissue of a patient to access atissue site1025. Thetissue site1025 may include a void1029 that is associated with a wound or other defect, or alternatively a void may be created by dissection, including the dissection techniques described herein.

Following placement of thedistal end1043 within thevoid1029 adjacent thetissue site1025, an injectable, pourable, or flowable reducedpressure delivery apparatus1035 is delivered through themanifold delivery tube1021 to thetissue site1025. The reducedpressure delivery apparatus1035 preferably exists in a flowable state during delivery to the tissue site, and then, after arrival forms a plurality of flow channels for distribution of reduced pressure or fluids. In some cases, the flowable material may harden into a solid state after arrival at the tissue site, either through a drying process, a curing process, or other chemical or physical reaction. In other cases, the flowable material may form a foam in-situ following delivery to the tissue site. Still other materials may exist in a gel-like state at thetissue site1025 but still have a plurality of flow channels for delivering reduced pressure. The amount of reducedpressure delivery apparatus1035 delivered to thetissue site1025 may be enough to partially or completely fill thevoid1029. The reducedpressure delivery apparatus1035 may include aspects of both a manifold and a scaffold. As a manifold, the reducedpressure delivery apparatus1035 includes a plurality of pores or open cells that may be formed in the material after delivery to thevoid1029. The pores or open cells communicate with one another, thereby creating a plurality of flow channels. The flow channels are used to apply and distribute reduced pressure to thetissue site1025. As a scaffold, the reducedpressure delivery apparatus1035 is bioresorbable and serves as a substrate upon and within which new tissue may grow.

In one embodiment, the reducedpressure delivery apparatus1035 may include poragens such as NaCl or other salts that are distributed throughout a liquid or viscous gel. After the liquid or viscous gel is delivered to thetissue site1025, the material conforms to thevoid1029 and then cures into a solid mass. The water-soluble NaCl poragens dissolve in the presence of bodily fluids leaving a structure with interconnected pores, or flow channels. Reduced pressure and/or fluid is delivered to the flow channels. As new tissue develops, the tissue grows into the pores of the reducedpressure delivery apparatus1035, and then ultimately replaces the reducedpressure delivery apparatus1035 as it degrades. In this particular example, the reducedpressure delivery apparatus1035 serves not only as a manifold, but also as a scaffold for new tissue growth.

In another embodiment, the reducedpressure delivery apparatus1035 is an alginate mixed with 400 μm mannose beads. The poragens or beads may be dissolved by local body fluids or by irrigational or other fluids delivered to the reducedpressure delivery apparatus1035 at the tissue site. Following dissolution of the poragens or beads, the spaces previously occupied by the poragens or beads become voids that are interconnected with other voids to form the flow channels within the reducedpressure delivery apparatus1035.

The use of poragens to create flow channels in a material is effective, but it also forms pores and flow channels that are limited in size to approximately the particle size of the selected poragen. Instead of poragens, a chemical reaction may be used to create larger pores due to the formation of gaseous by-products. For example, in one embodiment, a flowable material may be delivered to thetissue site1025 that contains sodium bicarbonate and citric acid particles (non-stoichiometric amounts may be used). As the flowable material forms a foam or solid in-situ, bodily fluids will initiate an acid-base reaction between the sodium bicarbonate and the citric acid. The resulting carbon dioxide gas particles that are produced create larger pore and flow channels throughout the reducedpressure delivery apparatus1035 than techniques relying on poragen dissolution.

The transformation of the reducedpressure delivery apparatus1035 from a liquid or viscous gel into a solid or a foam can be triggered by pH, temperature, light, or a reaction with bodily fluids, chemicals or other substances delivered to the tissue site. The transformation may also occur by mixing multiple reactive components. In one embodiment, the reducedpressure delivery apparatus1035 is prepared by selecting bioresorbable microspheres made from any bioresorbable polymer. The microspheres are dispersed in a solution containing a photoinitiator and a hydrogel-forming material such as hyaluronic acid, collagen, or polyethylene glycol with photoreactive groups. The microsphere-gel mixture is exposed to light for a brief period of time to partially crosslink the hydrogel and immobilize the hydrogel on the microspheres. The excess solution is drained, and the microspheres are then dried. The microspheres are delivered to the tissue site by injection or pouring, and following delivery, the mixture absorbs moisture, and the hydrogel coating becomes hydrated. The mixture is then again exposed to light, which crosslinks the microspheres, creating a plurality of flow channels. The crosslinked microspheres then serve as a manifold to deliver reduced pressure to the tissue site and as a porous scaffold to promote new tissue growth.

In addition to the preceding embodiments described herein, the reducedpressure delivery apparatus1035 may be made from a variety of materials, including without limitation calcium phosphate, collagen, alginate, cellulose, or any other equivalent material that is capable of being delivered to the tissue site as a gas, liquid, gel, paste, putty, slurry, suspension, or other flowable material and is capable of forming multiple flow paths in fluid communication with the tissue site. The flowable material may further include particulate solids, such as beads, that are capable of flowing through themanifold delivery tube1021 if the particulate solids are sufficiently small in size. Materials that are delivered to the tissue site in a flowable state may polymerize or gel in-situ.

As previously described, the reducedpressure delivery apparatus1035 may injected or poured directly into the void1029 adjacent thetissue site1025. Referring to FIG.27A, themanifold delivery tube1021 may include an impermeable orsemi-permeable membrane1051 at thedistal end1043 of themanifold delivery tube1021. Themembrane1051 includes aninner space1055 that fluidly communicates with asecondary lumen1057 attached to themanifold delivery tube1021. Themanifold delivery tube1021 is guided to thetissue site1025 over aguide wire1061.

The reducedpressure delivery apparatus1035 may be injected or poured through thesecondary lumen1057 to fill theinner space1055 of themembrane1051. As the fluid or gel fills themembrane1051, themembrane1051 expands to fill the void1029 such that the membrane is in contact with thetissue site1025. As themembrane1051 expands, themembrane1051 may be used to dissect additional tissue adjacent or near thetissue site1025. Themembrane1051, if impermeable, may be physically ruptured and removed, leaving behind the reducedpressure delivery apparatus1035 in contact with thetissue site1025. Alternatively, themembrane1051 may be made from a dissolvable material that dissolves in the presence of bodily fluids or biocompatible solvents that may be delivered to themembrane1051. If themembrane1051 is semi-permeable, themembrane1051 may remain in situ. Thesemi-permeable membrane1051 allows communication of reduced pressure and possibly other fluids to thetissue site1025.

Referring toFIG. 28, amethod1111 of administering a reduced pressure tissue treatment to a tissue site includes at1115 surgically inserting a manifold adjacent the tissue site, the manifold having a plurality of projections extending from a flexible barrier to create a plurality of flow channels between the projections. The manifold is positioned at1119 such that at least a portion of the projections are in contact with the tissue site. At1123, a reduced pressure is applied through the manifold to the tissue site.

Referring toFIG. 29, amethod1211 of administering a reduced pressure tissue treatment to a tissue site includes at1215 percutaneously inserting a manifold adjacent the tissue site. The manifold may include a plurality of projections extending from a flexible barrier to create a plurality of flow channels between the projections. Alternatively, the manifold may include cellular material having a plurality of flow channels within the cellular material. Alternatively, the manifold may be formed from an injectable or pourable material that is delivered to the tissue site and forms a plurality of flow channels after arriving at the tissue site. At1219, the manifold is positioned such that at a least a portion of the flow channels are in fluid communication with the tissue site. A reduced pressure is applied to the tissue site through the manifold at1223.

Referring toFIG. 30, amethod1311 of administering a reduced pressure tissue treatment to a tissue site includes at1315 percutaneously inserting a tube having a passageway through a tissue of a patient to place a distal end of the tube adjacent the tissue site. At1319, a balloon associated with the tube may be inflated to dissect tissue adjacent the tissue site, thereby creating a void. At1323, a manifold is delivered through the passageway. The manifold may include a plurality of projections extending from a flexible barrier to create a plurality of flow channels between the projections. Alternatively, the manifold may include cellular material having a plurality of flow channels within the cellular material. Alternatively, the manifold may be formed from an injectable or pourable material that is delivered to the tissue site as described previously with reference toFIG. 27. The manifold is positioned in the void at1327 such that at least a portion of the flow channels are in fluid communication with the tissue site. At1331, a reduced pressure is applied to the tissue site through, the manifold via a reduced pressure delivery tube or any other delivery means.

Referring toFIG. 31, a method1411 of administering a reduced pressure tissue treatment to a tissue site includes at1415 percutaneously inserting a tube having a passageway through a tissue of a patient to place a distal end of the tube adjacent the tissue site. At1423, a manifold is delivered through the passageway to the tissue site within an impermeable sheath, the impermeable sheath at1419 having been subjected to a first reduced pressure less than an ambient pressure of the sheath. At1427, the sheath is ruptured to place the manifold in contact with the tissue site. At1431, a second reduced pressure is applied through the manifold to the tissue site.

Referring toFIGS. 32 and 33, a reducedpressure delivery apparatus1511 according to an embodiment of the present invention includes anorthopedic hip prosthesis1515 for replacing the existing femoral head of afemur1517 of a patient. Thehip prosthesis1515 includes astem portion1521 and ahead portion1525. Thestem portion1521 is elongated for insertion within apassage1529 reamed in a shaft of thefemur1517. Aporous coating1535 is disposed around the stem portion and preferably is Constructed from sintered or vitrified ceramics or metal. Alternatively, a cellular material having porous characteristic could be disposed around the stem portion. A plurality offlow channels1541 is disposed within thestem portion1521 of thehip prosthesis1515 such that theflow channels1541 are in fluid communication with theporous coating1535. Aconnection port1545 is fluidly connected to theflow channels1541, the port being configured for releasable connection to a reducedpressure delivery tube1551 and a reducedpressure delivery source1553. Theflow channels1541 are used to deliver a reduced pressure to theporous coating1535 and/or the bone surrounding thehip prosthesis1515 following implantation. Theflow channels1541 may include amain feeder line1543 that fluidly communicates with severallateral branch lines1547, which communicate with theporous coating1535. Thelateral branch lines1545 may be oriented normal to themain feeder line1543 as illustrated inFIG. 32, or may be oriented at angles to themain feeder line1543. An alternative method for distributing the reduced pressure includes providing a hollow hip prosthesis, and filling the inner space of the prosthesis with a cellular (preferably open-cell) material that is capable of fluidly communicating with theporous coating1535.

Referring more specifically toFIG. 33,hip prosthesis1515 may further include a second plurality offlow channels1561 within thestem portion1521 to provide a fluid to theporous coating1535 and/or the bone surrounding thehip prosthesis1515. The fluid could include filtered air or other gases, antibacterial agents, antiviral agents, cell-growth promotion agents, irrigation fluids, chemically active fluids, or any other fluid. If it is desired to introduce multiple fluids to the bone surrounding thehip prosthesis1515, additional paths of fluid communication may be provided. Aconnection port1565 is fluidly connected to theflow channels1561, theport1565 being configured for releasable connection to afluid delivery tube1571 and afluid delivery source1573. Theflow channels1561 may include amain feeder line1583 that fluidly communicates with severallateral branch lines1585, which communicate with theporous coating1535. Thelateral branch lines1585 may be oriented normal to themain feeder line1583 as illustrated inFIG. 33, or may be oriented at angles to themain feeder line1583.

The delivery of reduced pressure to the first plurality offlow channels1541 and the delivery of the fluid to the second plurality offlow channels1561 may be accomplished by separate tubes such as reducedpressure delivery tube1551 andfluid delivery tube1571. Alternatively, a tube having multiple lumens as described previously herein may be used to separate the communication paths for delivering the reduced pressure and the fluid. It should further be noted that while it is preferred to provide separate paths of fluid communication within thehip prosthesis1515, the first plurality offlow channels1541 could be used to deliver both the reduced pressure and the fluid to the bone surrounding thehip prosthesis1515.

As previously described, application of reduced pressure to bone tissue promotes and speeds the growth of new bone tissue. By using thehip prosthesis1515 as a manifold to deliver reduced pressure to the area of bone surrounding the hip prosthesis, recovery of thefemur1517 is faster, and thehip prosthesis1515 integrates more successfully with the bone. Providing the second plurality offlow channels1561 to vent the bone surrounding thehip prosthesis1515 improves the successful generation of new bone around the prosthesis.

Following the application of reduced pressure through thehip prosthesis1515 for a selected amount of time, the reducedpressure delivery tube1551 andfluid delivery tube1571 may be disconnected from the

connection ports

1545,1565 and removed from the patient's body, preferably without a surgically-invasive procedure. The connection between the

connection ports

1545,1565 and the

tubes

1551,1571 may be a manually-releasable connection that is effectuated by applying an axially-oriented tensile force to the

tubes

1551,1571 on the outside of the patient's body. Alternatively, the

connection ports

1545,1565 may be bioresorbable or dissolvable in the presence of selected fluids or chemicals such that release of the

tubes

1551,1571 may be obtained by exposing the

connection ports

1545,1565 to the fluid or chemical. The

tubes

1551,1571 may also be made from a bioresorbable material that dissolves over a period of time or an activated material that dissolves in the presence of a particular chemical or other substance.

The reducedpressure delivery source1553 may be provided outside the patient's body and connected to the reducedpressure delivery tube1551 to deliver reduced pressure to thehip prosthesis1515. Alternatively, the reducedpressure delivery source1553 may be implanted within the patient's body, either on-board or near thehip prosthesis1515. Placement of the reducedpressure delivery source1553 within the patient's body eliminates the need for a percutaneous fluid connection. The implanted reducedpressure delivery source1553 may be a traditional pump that is operably connected to theflow channels1541. The pump may be powered by a battery that is implanted within the patient, or may be powered by an external battery that is electrically and percutaneously connected to the pump. The pump may also be driven directly by a chemical reaction that delivers a reduced pressure and circulates fluids through the

flow channels

1541,1561.

While only thestem portion1521 andhead portion1525 of thehip prosthesis1515 are illustrated inFIGS. 32 and 33, it should be noted that the flow channels and means for applying reduced pressure tissue treatment described herein could be applied to any component of thehip prosthesis1515 that contacts bone or other tissue, including for example the acetabular cup.

Referring toFIG. 34, amethod1611 for repairing a joint of a patient includes at1615 implanting a prosthesis within a bone adjacent the joint. The prosthesis could be a hip prosthesis as described above or any other prosthesis that assists in restoring mobility to the joint of the patient. The prosthesis includes a plurality of flow channels configured to fluidly communicate with the bone. At1619, a reduced pressure is applied to the bone through the plurality of flow channels to improve oseointegration of the prosthesis.

Theorthopedic fixation device1715 may be a plate as shown inFIG. 35, or alternatively may be a fixation device such as a sleeve, a brace, a strut, or any other device that is used to stabilize a portion of the bone. Theorthopedic fixation device1715 may further be fasteners used to attach prosthetic or other orthopedic devices or implanted tissues (e.g. bone tissues or cartilage), provided that the fasteners include flow channels for delivering reduced pressure to tissue adjacent to or surrounding the fasteners. Examples of these fasteners may include pins, bolts, screws, or any other suitable fastener.

Referring more specifically toFIG. 36, theorthopedic fixation device1715 may further include a second plurality offlow channels1761 within theorthopedic fixation device1715 to provide a fluid to theporous coating1735 and/or the bone surrounding theorthopedic fixation device1715. The fluid could include filtered air or other gases, antibacterial agents, antiviral agents, cell-growth promotion agents, irrigation fluids, chemically active agents, or any other fluid. If it is desired to introduce multiple fluids to the bone surrounding theorthopedic fixation device1715, additional paths of fluid communication may be provided. Aconnection port1765 is fluidly connected to theflow channels1761, theport1765 being configured for connection to afluid delivery tube1771 and afluid delivery source1773. Theflow channels1761 may include amain feeder line1783 that fluidly communicates with severallateral branch lines1785, which communicate with theporous coating1735. Thelateral branch lines1785 may be oriented normal to themain feeder line1783 as illustrated inFIG. 33, or may be oriented at angles to themain feeder line1783.

The delivery of reduced pressure to the first plurality offlow channels1741 and the delivery of the fluid to the second plurality offlow channels1761 may be accomplished by separate tubes such as reducedpressure delivery tube1751 andfluid delivery tube1771. Alternatively, a tube having multiple lumens as described previously herein may be used to separate the communication paths for delivering the reduced pressure and the fluid. It should further be noted that while it is preferred to provide separate paths of fluid communication within theorthopedic fixation device1715, the first plurality offlow channels1741 could be used to deliver both the reduced pressure and the fluid to the bone adjacent theorthopedic fixation device1715.

The use oforthopedic fixation device1715 as a manifold to deliver reduced pressure to the area of bone adjacent theorthopedic fixation device1715 speeds and improves recovery of thedefect1719 of thebone1717. Providing the second plurality offlow channels1761 to communicate fluids to the bone surrounding theorthopedic fixation device1715 improves the successful generation of new bone near the orthopedic fixation device.

Referring toFIG. 37, amethod1811 for healing a bone defect of a bone includes at1815 fixating the bone using an orthopedic fixation device. The orthopedic fixation device includes a plurality of flow channels disposed within the orthopedic fixation device. At1819, a reduced pressure is applied to the bone defect through the plurality of flow channels.

Referring toFIG. 38, amethod1911 for administering reduced pressure tissue treatment to a tissue site includes at1915 positioning a manifold having a plurality of flow channels such that at least a portion of the flow channels are in fluid communication with the tissue site. A reduced pressure is applied at1919 to the tissue site through the flow channels, and a fluid is delivered at1923 to the tissue site through the flow channels

Referring toFIG. 39, amethod2011 for administering reduced pressure tissue treatment to a tissue site includes at2015 positioning a distal end of a manifold delivery tube adjacent the tissue site. At2019 a fluid is delivered through the manifold delivery tube to the tissue site. The fluid is capable of filling a void adjacent the tissue site and becoming a solid manifold having a plurality of flow channels in fluid communication with the tissue site. A reduced pressure is applied at2023 to the tissue site through the flow channels of the solid manifold.

Referring toFIGS. 40-48, a reducedpressure delivery system2111 includes aprimary manifold2115 having aflexible wall2117 surrounding aprimary flow passage2121. Theflexible wall2117 is connected at aproximal end2123 to a reducedpressure delivery tube2125. Since the shape of the reducedpressure delivery tube2125 will typically be round in cross-section, and since the shape of theprimary manifold2115 in cross-section may be other than round (i.e. rectangular inFIGS. 40-45 and triangular inFIGS. 46-48), atransition region2129 is provided between the reducedpressure delivery tube2125 and theprimary manifold2115. Theprimary manifold2115 may be adhesively connected to the reducedpressure delivery tube2125, connected using other means such as fusing or insert molding, or alternatively may be integrally connected by co-extrusion. The reducedpressure delivery tube2125 delivers reduced pressure to theprimary manifold2115 for distribution at or near the tissue site.

Ablockage prevention member2135 is positioned within the primary manifold to prevent collapse of the manifold2115, and thus blockage of theprimary flow passage2121 during application of reduced pressure. In one embodiment, theblockage prevention member2135 may be a plurality of projections2137 (seeFIG. 44) disposed on aninner surface2141 of theflexible wall2117 and extending into theprimary flow passage2121. In another embodiment, theblockage prevention member2135 may be a single ormultiple ridges2145 disposed on the inner surface2141 (seeFIGS. 40 and 41). In yet another embodiment, theblockage prevention member2135 may include acellular material2149 disposed within the primary flow passage such as that illustrated inFIG. 47. Theblockage prevention member2135 may be any material or structure that is capable of being inserted within the flow passage or that is capable of being integrally or otherwise attached to theflexible wall2117. Theblockage prevention member2135 is able to prevent total collapse of theflexible wall2117, while still allowing the flow of fluids through theprimary flow passage2121.

Theflexible wall2117 further includes a plurality ofapertures2155 through theflexible wall2117 that communicate with theprimary flow passage2121. Theapertures2155 allow reduced pressure delivered to theprimary flow passage2121 to be distributed to the tissue site.Apertures2155 may be selectively positioned around the circumference of the manifold2115 to preferentially direct the delivery of vacuum. For example, inFIG. 51, apertures may be placed facing the bone, facing the overlying tissue, or both.

The reducedpressure delivery tube2125 preferably includes afirst conduit2161 having at least one outlet fluidly connected to theprimary flow passage2121 to deliver reduced pressure to theprimary flow passage2121. Asecond conduit2163 may also be provided to purge theprimary flow passage2121 and thefirst conduit2161 with a fluid to prevent or resolve blockages caused by wound exudate and other fluids drawn from the tissue site. Thesecond conduit2163 preferably includes at least one outlet positioned proximate to at least one of theprimary flow passage2121 and the at least one outlet of thefirst conduit2161.

Referring more specifically toFIGS. 40 and 41, the reducedpressure delivery system2111 thesecond conduit2163 may include multiple conduits for purging theprimary flow passage2121 and thefirst conduit2161. While the end of theflexible wall2117 opposite the end attached to reducedpressure delivery tube2125 may be open as illustrated inFIG. 40, it has been found that capping the end of theflexible wall2117 may improve the performance and reliability of the purging function. Preferably, ahead space2171 is provided for between the capped end of the flexible wall and the end of thesecond conduits2163. Thehead space2171 allows for a buildup of purge fluid during the purging process, which helps drive the purge fluid through theprimary flow passage2121 and into thefirst conduit2161.

Also illustrated inFIG. 41 is the divider that serves as theblockage prevention member2135. The centrally-located divider bifurcates theprimary flow passage2121 into two chambers, which allows continued operation of theprimary manifold2115 if one of the chambers becomes blocked and purging is unable to resolve the blockage.

Referring toFIGS. 49 and 50, a reducedpressure delivery system2211 includes aprimary manifold2215 that is integral to a reducedpressure delivery tube2217. The reducedpressure delivery tube2217 includes acentral lumen2223 and a plurality ofancillary lumens2225. While theancillary lumens2225 may used to measure pressure at or near the tissue site, theancillary lumens2225 may further be used to purge thecentral lumen2223 to prevent or resolve blockages. A plurality ofapertures2231 communicate with thecentral lumen2223 to distribute the reduced pressure delivered by thecentral lumen2223. As illustrated inFIG. 50, it is preferred that theapertures2231 not penetrate theancillary lumens2225. Also illustrated inFIG. 50 is the countersunk end of the reduced pressure delivery tube, which creates ahead space2241 beyond the end of theancillary lumens2225. If tissue, scaffolds, or other materials were to engage the end of the reducedpressure delivery tube2217 during application of reduced pressure, thehead space2241 would continue to allow purging fluid to be delivered to thecentral lumen2223.

In operation, the reduced

pressure delivery systems

2111,2211 ofFIGS. 40-50 may be applied directly to a tissue site for distributing reduced pressure to the tissue site. The low-profile shape of the primary manifolds is highly desirous for the percutaneous installation and removal techniques described herein. Similarly, the primary manifolds may also be inserted surgically.

Referring toFIG. 51, the

primary manifolds

2115,2215 may be used in conjunction with asecondary manifold2321. InFIG. 51, thesecondary manifold2321 includes a two-layered felted mat. The first layer of thesecondary manifold2321 is placed in contact with a bone tissue site that includes a bone fracture. Theprimary manifold2115 is placed in contact with the first layer, and the second layer of thesecondary manifold2321 is placed on top of theprimary manifold2115 and first layer. Thesecondary manifold2321 allows fluid communication between theprimary manifold2115 and the tissue site, yet prevents direct contact between the tissue site and theprimary manifold2115.

Preferably, thesecondary manifold2321 is bioabsorbable, which allows thesecondary manifold2321 to remain in situ following completion of reduced pressure treatment. Upon completion of reduced pressure treatment, theprimary manifold2115 may be removed from between the layers of the secondary manifold with little or no disturbance to the tissue site. In one embodiment, the primary manifold may be coated with a lubricious material or a hydrogel-forming material to ease removal from between the layers.

The secondary manifold preferably serves as a scaffold for new tissue growth. As a scaffold, the secondary manifold may be comprised of at least one material selected from the group of polylactic acid, polyglycolic acid, polycaprolactone, polyhydroxybutyrate, polyhydroxyvalerate, polydioxanone, polyorthoesthers, polyphosphazenes, polyurethanes, collagen, hyaluronic acid, chitosan, hydroxyapatite, calcium phosphate, calcium sulfate, calcium carbonate, bioglass, stainless steel, titanium, tantalum, allografts, and autografts.

The purging function of the reduced

pressure delivery systems

2111,2211 described above may be employed with any of the manifolds described herein. The ability to purge a manifold or a conduit delivering reduced pressure prevents blockages from forming that hinder the administration of reduced pressure. These blockages typically form as the pressure near the tissue site reaches equilibrium and egress of fluids around the tissue site slows. It has been found that purging the manifold and reduced pressure conduit with air for a selected amount of time at a selected interval assists in preventing or resolving blockages.

More specifically, air is delivered through a second conduit separate from a first conduit that delivers reduced pressure. An outlet of the second conduit is preferably proximate to the manifold or an outlet of the first conduit. While the air may be pressurized and “pushed” to the outlet of the second conduit, the air is preferably drawn through the second conduit by the reduced pressure at the tissue site. It has been found that delivery of air for two (2) seconds at intervals of sixty (60) seconds during the application of reduced pressure is sufficient to prevent blockages from forming in many instances. This purging schedule provides enough air to sufficiently move fluids within the manifold and first conduit, while preventing the introduction of too much air. Introducing too much air, or introducing air at too high of an interval frequency will result in the reduced pressure system not being able to return to the target reduced pressure between purge cycles. The selected amount of time for delivering a purging fluid and the selected interval at which the purging fluid is delivered will typically vary based on the design and size of system components (e.g. the pump, tubing, etc.). However, air should be delivered in a quantity and at a frequency that is high enough to sufficiently clear blockages while allowing the full target pressure to recover between purging cycles.

Referring toFIG. 52, in one illustrative embodiment, a reducedpressure delivery system2411 includes a manifold2415 fluidly connected to afirst conduit2419 and asecond conduit2423. Thefirst conduit2419 is connected to a reducedpressure source2429 to provide reduced pressure to themanifold2415. Thesecond conduit2423 includes anoutlet2435 positioned in fluid communication with the manifold2415 and proximate an outlet of thefirst conduit2419. Thesecond conduit2423 is fluidly connected to avalve2439, which is capable of allowing communication between thesecond conduit2423 and the ambient air when the valve is placed in an open position. Thevalve2439 is operably connected to acontroller2453 that is capable of controlling the opening and closing of thevalve2439 to regulate purging of the second conduit with ambient air to prevent blockages within themanifold2415 and thefirst conduit2419.

It should be noted that any fluid, including liquids or gases, could be used to accomplish the purging techniques described herein. While the driving force for the purging fluid is preferably the draw of reduced pressure at the tissue site, the fluid similarly could be delivered by a fluid delivery means similar to that discussed with reference toFIG. 9.

The administration of reduced pressure tissue treatment to a tissue site in accordance with the systems and methods described herein may be accomplished by applying a sufficient reduced pressure to the tissue site and then maintaining that sufficient reduced pressure over a selected period of time. Alternatively, the reduced pressure that is applied to the tissue site may be cyclic in nature. More specifically, the amount of reduced pressure applied may be varied according to a selected temporal cycle. Still another method of applying the reduced pressure may vary the amount of reduced pressure randomly. Similarly, the rate or volume of fluid delivered to the tissue site may be constant, cyclic, or random in nature. Fluid delivery, if cyclic, may occur during application of reduced pressure, or may occur during cyclic periods in which reduced pressure is not being applied. While the amount of reduced pressure applied to a tissue site will typically vary according to the pathology of the tissue site and the circumstances under which reduced pressure tissue treatment is administered, the reduced pressure will typically be between about −5 mm Hg and −500 mm Hg, but more preferably between about −5 mm Hg and −300 mm Hg.

While the systems and methods of the present invention have been described with reference to tissue growth and healing in human patients, it should be recognized that these systems and methods for applying reduced pressure tissue treatment can be used in any living organism in which it is desired to promote tissue growth or healing. Similarly, the systems and methods of the present invention may be applied to any tissue, including without limitation bone tissue, adipose tissue, muscle tissue, neural tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, or ligaments. While the healing of tissue may be one focus of applying reduced pressure tissue treatment as described herein, the application of reduced pressure tissue treatment, especially to tissues located beneath a patient's skin, may also be used to generate tissue growth in tissues that are not diseased, defective, or damaged. For example, it may be desired to use the percutaneous implantation techniques to apply reduced pressure tissue treatment to grow additional tissue at a tissue site that can then be harvested. The harvested tissue may be transplanted to another tissue site to replace diseased or damaged tissue, or alternatively the harvested tissue may be transplanted to another patient.

It is also important to note that the reduced pressure delivery apparatuses described herein may be used in conjunction with scaffold material to increase the growth and growth rate of new tissue. The scaffold material could be placed between the tissue site and the reduced pressure delivery apparatus, or the reduced pressure delivery apparatus could itself be made from bioresorbable material that serves as a scaffold to new tissue growth.

It should be apparent from the foregoing that an invention having significant advantages has been provided. While the invention is shown in only a few of its forms, it is not just limited but is susceptible to various changes and modifications without departing from the spirit thereof.