US20070118143A1 - Systems and methods for reducing fractured bone using a fracture reduction cannula - Google Patents

Abstract

Systems and methods provide for the fixation of osteoporotic and non-osteoporotic long bones, especially Colles' fractures. A cannula having a circumferential opening is inserted into cancellous bone and directed such that the circumferential opening faces the fracture. The cannula is further adapted to receive an expandable structure, the expandable structure being inserted through the cannula until it is in registration with the circumferential opening. The expandable structure is expanded through the circumferential opening into cancellous bone and toward the fracture. The expansion of the expandable structure through the circumferential opening toward the fracture causes compression of cancellous bone and moves fractured cortical bone, thus creating a cavity proximal to the fracture. The cavity is then filled with a flowable bone filling material and the material allowed to harden.

Description

RELATED APPLICATIONS
• This application is a divisional of co-pending application Ser. No. 10/001,937 filed 25 Oct. 2001 which is a Continuation-in-part of application Ser. No. 09/804,107 filed 12 Mar. 2001 (now U.S. Pat. No. 6,613,054), which is a divisional of application Ser. No. 09/134,323 filed 14 Aug. 1998 (now U.S. Pat. No. 6,241,734). This application also claims the benefit of provisional application Ser. No. 60.243,194 filed 25 Oct. 2000.
FIELD OF THE INVENTION
• This invention relates to the treatment of bone conditions of the human and other animal body systems and, more particularly, to systems and methods for correcting such conditions.
BACKGROUND OF THE INVENTION
• Bone fractures, particularly osteoporotic bone fractures, are common in older adults. Due to the nature of osteoporotic bone, standard methods of fracture fixation yield unsatisfactory results. Such methods cannot adequately place the broken fragments back to their pre-fracture state. For instance, with a non- osteoporotic bone fracture, common practice includes inserting rods, pins and/or screws into the bone in order to reduce the fracture and/or fix the fracture fragments to plates. Osteoporotic bone generally cannot support such a method. Another common method for non-osteoporotic bone fractures involves maintaining the bone in a cast for several weeks. Osteoporotic bone that has suffered a crush fracture, such as a Colles' fracture of the distal radius, will not heal properly if placed in a cast; the bone mechanics are altered such that the bone is shortened and/or subsides. Yet another non-osteoporotic fracture reduction method involves using an external fixation device. However, when used in elderly patients, the fixation pins may not remain within the weakened bone. Moreover, such a device typically increases the likelihood of infection at the treatment site. Further, because casts and/or an external fixation devices must be left in place for several weeks in order for the bone to heal, the lack of joint movement in the affected area often results in painful arthritis in the immobilized joints of the elderly patient.
• Even where osteoporosis is not present, it is typically necessary to immobilize a fractured bone to allow the bone to properly heal. This often requires immobilization of the joints adjacent to the fractured bone—often for extended periods of time. However, such immobilization often causes the joints to degenerate over time. Often, such treatment can result in temporary or permanent loss of joint motion. At the very least, such immobilization of the joints requires extensive and often painful rehabilitation for an individual to recover the full range of their joint motion.
SUMMARY OF THE INVENTION
• Because of the problems associated with treating distal radius fractures such as Colles' fractures, and other bone fractures similar thereto, there is a need for a method and apparatus that will improve the existing protocol for treating such fractures such as reducing the pain resulting from the fracture fixation method used, reducing the chance that an infection will occur at the site, improving the likelihood that the fracture will heal properly and minimizing degeneration of the adjacent joints and allows for sooner resumption of activity. The present invention provides apparatus and a method of fracture reduction which satisfies this need.
• This invention provides a system that fixes or reduces osteoporotic and non-osteoporotic fractures in human and other animal body systems. Moreover, by immediately reducing and/or reinforcing the fractured bone, thereby rendering the bone capable of bearing limited loads, the present system promotes healing of the fractured bone while minimizing degeneration of the adjacent joints. It is particularly well suited for fractures of long bones such as the human distal radius.
• One aspect of the invention provides a tool for establishing a percutaneous path into bone. The tool is a cannula having a side wall defining an internal bore aligned along an axis. The cannula has a distal end. A circumferential opening is defined in the side wall. The circumferential opening has a distal terminus. The circumferential opening extends partially about the side wall and is elongated along the axis. The circumferential opening is adapted to accommodate passage of an expandable structure from within the bore. In one embodiment, the bore is solid between the distal terminus of the circumferential opening and the distal end of the cannula.
• In an alternate embodiment of the above described tool, the bore is open between the distal terminus of the circumferential opening and the distal end of the cannula. The cannula has a distal opening in the distal end communicating with the bore. The opening in the distal end can accommodate passage of a guide pin.
• In an alternate embodiment of the above described tool, the cannula desirably has a surface on its distal end to anchor the distal end in bone.
• Another aspect of the invention provides an assembly for treating bone, including a cannula as described above. The cannula has a distal opening in the distal end communicating with the bore. The opening in the distal end can accommodate passage of a guide pin. The assembly also includes an expandable structure. The expandable structure is adapted for insertion through bone into the cannula and expansion through the circumferential opening.
• Another aspect of the invention provides an assembly for treating bone, including a cannula as described above. Desirably, the bore is solid between the distal terminus of the circumferential opening and the distal end of the cannula. The assembly also includes an expandable structure. The expandable structure is adapted for insertion through bone into the cannula and expansion through the circumferential opening.
• Another aspect of the invention provides an assembly for treating bone, including a cannula as described above. Desirably, the cannula has a surface on its distal end to anchor the distal end in bone. The assembly also includes an expandable structure. The expandable structure is adapted for insertion through bone into the cannula and expansion through the circumferential opening.
• Another aspect of the invention provides an assembly as described above. Desirably, the expandable structure has radio opaque markers. The markers allow one to locate the expandable structure within a circumferential opening in a cannula.
• Another aspect of the invention provides a method for treating bone. The method includes providing a cannula and inserting the cannula into cancellous bone. The method also includes inserting an expandable structure through the cannula until the structure is in registration with a circumferential opening in the cannula. The method further includes expanding the expandable structure through the circumferential opening into contact with cancellous bone.
• Another aspect of the invention provides a method for treating bone, including a step of expanding an expandable structure. The expansion compacts cancellous bone.
• Another aspect of the invention provides a method for treating bone, including a step of compacting cancellous bone. The compaction of cancellous bone forms a cavity.
• Another aspect of the invention provides a method for treating bone, including a step of conveying a material into a cavity.
• Another aspect of the invention provides a method for treating bone, including a step of expanding an expandable structure such that the expansion moves fractured cortical bone.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is an anatomic view that shows bones of a human forearm;
• FIG. 2 is an anatomic view that shows bones of the forearm including an ulna and a fractured distal radius;
• FIG. 3 is an enlarged section view of the distal radius showing cancellous bone and cortical bone in a fractured condition;
• FIG. 4 is a plane view showing a kit containing a system of instruments used to treat bones and that embodies features of the invention;
• FIG. 5 is a perspective view of an obturator instrument that is contained in the kit shown inFIG. 4;
• FIG. 6 is a perspective view of a percutaneous cannula that is contained in the kit shown inFIG. 4;
• FIG. 7 is a perspective view of a drill bit instrument that is contained in the kit shown inFIG. 4;
• FIG. 8 is a perspective view of a fracture reduction cannula that is contained in the kit shown inFIG. 4, showing a distal end, a proximal end, and a circumferential opening;
• FIG. 8A is a perspective view of an alternate embodiment of a fracture reduction cannula constructed in accordance with the teachings of the present invention;
• FIG. 8B is a perspective view of another alternate embodiment of a fracture reduction cannula constructed in accordance with the teachings of the present invention;
• FIG. 9 is a side view of the fracture reduction cannula ofFIG. 8 showing an end interior bore therethrough;
• FIG. 10ais an enlarged view of the distal end of the fracture reduction cannula, the distal end being solid;
• FIG. 10bis an enlarged view of the distal end of the fracture reduction cannula ofFIG. 8, the distal end being open to accommodate passage of a guide pin;
• FIG. 11 is a perspective view of an instrument carrying an expandable structure, the instrument being contained in the kit shown inFIG. 4;
• FIG. 12 is an enlarged perspective view of an instrument, showing the expandable structure in an unexpanded state and, in broken lines, the expandable structure in an expanded state;
• FIG. 13 is a perspective view of a tamp that is contained in the kit shown inFIG. 4;
• FIG. 14 is a perspective view of a handle that is contained in the kit shown inFIG. 4; showing recesses therein;
• FIG. 15 is a perspective view showing the obturator instrument inserted into the handle, the handle being grasped by a hand;
• FIG. 15ais a side section view showing the obturator instrument inserted into the handle and advanced to the distal radius;
• FIG. 16 is a side section view showing the percutaneous cannula inserted over the obturator instrument and advanced to the distal radius;
• FIG. 17 is a side section view showing the drill bit instrument within the percutaneous cannula and advanced to the distal radius, and further showing the distal radius fracture and cancellous bone;
• FIG. 18 is a side section view showing the fracture reduction cannula within the percutaneous cannula and advanced into the cancellous bone of the distal radius, and further showing the circumferential opening facing the fracture;
• FIG. 19 is an enlarged view showing the fracture reduction cannula seated within cortical bone;
• FIG. 20 is an enlarged view showing the fracture reduction cannula seated within cortical bone and containing the unexpanded expandable structure;
• FIG. 21 is an enlarged view showing the fracture reduction cannula seated within cortical bone, containing the expanded expandable structure, and compressing cancellous bone and/or moving cortical bone;
• FIG. 21A is an enlarged view showing a fracture reduction cannula seated within cortical bone, with the expanded expandable structure compressing cancellous bone and/or moving cortical bone and creating a cavity which extends across a fracture line in the targeted bone;
• FIG. 22 is an enlarged view showing the fracture reduction cannula seated within cortical bone and containing the expanded expandable structure, showing compressed cancellous bone, displaced cortical bone, and a reduced fracture, and further showing a pin placed through the distal radius and into the ulna;
• FIG. 22A is an enlarged view showing a fracture reduction cannula seated within cortical bone and containing the expanded expandable structure, showing compressed cancellous bone, displaced cortical bone, a reduced fracture, and a cavity extending across a fracture line in the cortical bone, and further showing a pin placed through the distal radius and into the ulna;
• FIG. 23 is a top view showing a patient's forearm on a rolled towel, with horizontal finger traps on the patient's fingers, the instrument inserted through the handle and into the percutaneous cannula, with the fraction reduction cannula hidden from view, and the pin inserted into the patient's wrist;
• FIG. 24 is an enlarged view showing a cavity created by expansion of the expandable structure in the distal radius, the pin in place, the fracture reduction cannula, and the cavity ready to receive a bone filling material;.
• FIG. 25 is an enlarged view showing the filling material beginning to fill the cavity;
• FIG. 26 is an enlarged view showing the tamp urging the filling material fully into the cavity;
• FIG. 27 is an enlarged view showing the filled cavity with the fracture reduction cannula and tamp removed; and
• FIG. 28 is an enlarged view showing an alternate embodiment of the fracture reduction cannula with a guide pin placed therethrough.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
• The invention may be embodied in several forms without departing from its spirit or essential characteristics. The scope of the invention is defined in the appended claims, rather than in the specific description preceding them. All embodiments that fall within the meaning and range of equivalency of the claims are therefore intended to be embraced by the claims.
• The preferred embodiment describes improved systems and methods that embody features of the invention in the context of treating bones. This is because the new systems and methods are advantageous when used for this purpose. However, aspects of the invention can be advantageously applied for diagnostic or therapeutic purposes in other areas of the body.
• The new systems and methods will be more specifically described in the context of the treatment of long bones such as the human distal radius. Of course, other human or animal bone types can be treated in the same or equivalent fashion.
• I. Anatomy of the Radius
• The human forearm consists of two bones, the radius and the ulna. As shown inFIGS. 1 and 2, theradius20 is a long bone that is situated on the thumb side of the forearm, while theulna26 is located at the little finger side. Theradius20 lies side by side with theulna26, and it exceeds theulna26 both in length and in size.
• The upper, orproximal end22 of theradius20 is small and articulates with a part of the elbow joint, including theproximal ulna28. Thedistal end24 of theradius20 is large and articulates with two bones of the wrist, or carpus, known as the lunate21 andscaphoid27 bones. The inner, ormedial side25 of thedistal radius24 contains an ulnar notch32 that articulates with theulna26.
• II. Bone Fractures
• The systems and methods of the present invention are especially suited for treating fractures of long bones. One type of bone fracture that may be so treated is known as a Colles' fracture or transverse wrist fracture. As shown inFIG. 2, such afracture34 generally occurs less than one inch from thedistal end24 of theradius20. Colles' fractures are commonly noted in children and the elderly where the person tries to break or stop a fall by using his or her hands and arms. Colles' fractures in children are often associated with sports such as skateboarding and in-line skating. In the elderly, Colles' fractures are commonly caused by osteoporosis and/or in connection with a fall.
• Osteoporosis is a disease of the bone that is most commonly found in the middle-aged and elderly, particularly women. It is characterized by a gradual loss of a type of bone tissue known ascancellous bone36. As shown inFIG. 3,cancellous bone36, also referred to as trabecular bone, is a spongy bone tissue located within the harder outer or cortical bone.Cancellous bone36 comprises most of the bone tissue of the extremities of long bones such as theradius20.
• In contrast tocancellous bone36,cortical bone38 tissue is much harder and denser.Cortical bone38 is layered overcancellous bone36, and provides a protective layer and support for long bones such as theradius20, as shown inFIGS. 1 and 2. At the ends of such bones, however, thecortical bone38 layer becomes thinner. Where osteoporosis has significantly weakened thecancellous bone36, such regions at the ends of long bones become especially prone to fracture and/or collapse.
• It may be indicated, due to disease or trauma, to reduce fracturedcortical bone38 and/or compresscancellous bone36 within long bones such as theradius20. The compression, for example, can be used to form aninterior cavity35, which receives a fillingmaterial99, e.g., a flowable material that sets to a hardened condition, such as poly(methylmethacrylate), as well as a medication, or combinations thereof, to provide improved interior support forcortical bone38 or other therapeutic functions, or both. The compaction ofcancellous bone36 also exerts interior force uponcortical bone38, making it possible to elevate or push broken and compressed bone back to or near its original pre-fracture, or other desired, condition.
• III. The Instruments
• FIG. 4 shows instruments, arranged as akit200, which are usable in association with each other to reduce fractured bone. The number and type of instruments can vary.FIG. 4 shows seven representative instruments, each having a different size and function.
• InFIG. 4, thekit200 includes anobturator instrument12 for penetrating soft tissue and bone; apercutaneous cannula14 that functions as a guide sheath; adrill bit instrument16 that is used for drilling into bone; afracture reduction cannula18 used in reducing fractures and that is inserted into bone and designed to receive an expandable structure; abone compaction instrument80 that functions to deliver a fillingmaterial99 into acavity35 in bone and that carries anexpandable structure86 that may be expanded in bone; a tamp81 functions to urge residual bone filling material into bone; and ahandle13 with recesses that receivesinstruments12,14,16 and18.
• Instruments12,14,16, and18 share some common features, although they are intended, in use, to perform different functions.Instruments12,14,16, and18 each comprise an elongated, cylindrical body40 having aproximal end42 and adistal end44.Instruments12,14,16, and18 are each made of a rigid, surgical grade plastic or metal material.
• A. The Obturator Instrument
• Thefirst instrument12 functions as an obturator. As shown inFIG. 5, itsdistal end44 is tapered to present a penetratingsurface50. In use, thesurface50 is intended to penetrate soft tissue and/or bone in response to pushing or twisting forces applied by the physician at theproximal end42. In a preferred embodiment, theproximal end42 of theobturator instrument12 mates with ahandle13, to be described in detail later.
• Theproximal end42 of theobturator instrument12 presents aflanged surface52. Theflanged surface52 is designed to fit securely into a recess in thehandle13, such that pushing or twisting forces applied to theproximal end42 of theobturator12 instrument will not displace theobturator instrument12. Theflanged surface52 tapers from a larger outer diameter to a smaller outer diameter in the direction of theproximal end42. Theflanged surface52 includes an array of circumferentially spacedteeth54 withintermediate flutes56.
• An interior bore60 extends through theobturator instrument12 from thedistal end44 to theproximal end42. Desirably, the interior bore60 is sized to accommodate a conventionalsurgical guide pin108 component to aid in its deployment, as will be described in greater detail later.
• Theobturator instrument12 has anouter surface142 that is sized such that one may slide apercutaneous cannula14 over theobturator instrument12 as described below.
• B. The Percutaneous Cannula
• Thesecond instrument14 functions as a percutaneous cannula or guide sheath. It also serves to protect soft tissue and nerves, ligaments, muscle and vasculature from the use of adrill bit instrument16, which will be described in greater detail later.
• As shown inFIG. 6, thepercutaneous cannula14 is somewhat larger in diameter than, and is not as long as, theobturator instrument12. In one embodiment, thecannula14 is approximately2 inches long, although it could be various other lengths, depending upon the thickness of the patient's soft tissue at the surgical site. Desirably, thepercutaneous cannula14 is made of metal, and containsmarkings120 along itsouter surface142 to indicate the depth at which it is placed into a patient'sdistal radius24.
• Theproximal end42 of thepercutaneous cannula14 presents a taperedflange52, asFIG. 6 shows. Theflanged surface52 is designed to fit securely into a recess in thehandle13, such that forces applied to theproximal end42 of thepercutaneous cannula14 will not displace thepercutaneous cannula14. The taperedflange52 changes from a larger diameter to a smaller diameter in the direction of theproximal end42. The taperedflange52 of thepercutaneous cannula14 also includes an array of circumferentially spacedteeth54 withintermediate flutes56. The form and orientation of theteeth54 andflutes56 on thepercutaneous cannula14 correspond to the form and orientation ofteeth54 andflutes56 on thefracture reduction cannula18.
• As shown inFIG. 6, thepercutaneous cannula14 includes aninterior bore60 that extends from itsdistal end44 to itsproximal end42. Desirably, the interior bore60 is sized to accept theobturator instrument12. The size of the interior bore60 permits a physician to slide and rotate thepercutaneous cannula14 relative to theobturator instrument12, and vice versa, as will be described in greater detail later.
• Thedistal end44 of thepercutaneous cannula14 presents anend surface62. Desirably, the surface of thedistal end44 is designed to penetrate soft tissue. In use, theend surface62 of thepercutaneous cannula14 is intended to penetrate soft tissue surrounding theobturator instrument12, in response to pushing or twisting forces applied at theproximal end42. If desired, theend surface62 can incorporate one or more teeth (not shown) which anchor thecannula14 to the surface of the targeted bone.
• C. The Drill Bit Instrument
• The third instrument functions as a drill bit. As shown inFIG. 7, Thedrill bit instrument16 has generally the same physical dimensions as theobturator instrument12. Like theobturator instrument12, thedrill bit instrument16 is intended, in use, to fit for sliding and rotational movement within the interior bore60 of thepercutaneous cannula14.
• Thedistal end44 of thedrill bit instrument16 includes machinedcutting edges64, as shown inFIG. 7. In use, the cutting edges64 are intended to penetrate hard tissue in response to rotation and longitudinal load forces applied at theproximal end42 of thedrill bit instrument16.
• As further shown inFIG. 7, theproximal end42 presents a taperedflange52, substantially identical to theflange52 on theobturator instrument12, asFIG. 5 shows. Theflanged surface52 is designed to fit securely into a recess in thehandle13, such that forces applied to theproximal end42 of thedrill bit instrument14 will not displace thedrill bit instrument14. Like theobturator instrument12, the taperedflange52 changes from a larger diameter to a smaller diameter in the direction of theproximal end42. The taperedflange52 of thedrill bit instrument16 also includes an array of circumferentially spacedteeth54 withintermediate flutes56. The form and orientation of theteeth54 andflutes56 on thedrill bit instrument16 correspond to the form and orientation of theteeth54 andflutes56 on theobturator instrument12.
• D. The Fracture Reduction Cannula
• The fourth instrument functions as afracture reduction cannula18. As shown inFIG. 8, thefracture reduction cannula18 is somewhat smaller in diameter than, and is longer than, thepercutaneous cannula14. In one embodiment, thefracture reduction cannula18 is approximately3 M inches in length, although it could be various other lengths depending on the size of the patient and the desired location within the targeted bone. Like both theobturator instrument12 and thedrill bit instrument16, thefracture reduction cannula18 is intended, in use, to fit for sliding and rotational movement within the interior bore60 of thepercutaneous cannula14.
• Theproximal end42 of thefracture reduction cannula18 presents aflanged surface52. Theflanged surface52 is designed to fit securely into a recess in thehandle13, such that pushing or twisting forces applied to theproximal end42 of theobturator12 instrument will not displace thefracture reduction cannula18. Like thepercutaneous cannula14, theflanged surface52 of thefracture reduction cannula18 tapers from a larger outer diameter to a smaller outer diameter in the direction of theproximal end42. Theflanged surface52 includes an array of circumferentially spacedteeth54 withintermediate flutes56.
• Thefracture reduction cannula18 is sized to fit within the interior bore60 of thepercutaneous cannula14. The size of the interior bore60 permits a physician to slide and rotate the fraction reduction cannula relative topercutaneous cannula14, and vice versa, as will be described in greater detail later.
• As further shown inFIG. 8, thefracture reduction cannula18 includes aside wall66 that defines aninterior bore68 that extends from thedistal end44 of thefracture reduction cannula18 to itsproximal end42. The interior bore68 is adapted to allow passage of, among other things, anexpandable structure86. In a preferred embodiment, thedistal end44 of the interior bore68 is solid, as shown inFIG. 10a.In an alternate embodiment, thedistal end44 of thebore68 is not solid, but rather, it is open to accommodate passage of an instrument such as aguide pin108, as shown inFIG. 10b.As another alternative, the distal end of thebore68 could be hollow, such that a portion of the expandable structure could extend into thedistal end44 of thecannula18.
• Thefracture reduction cannula18 further includes acircumferential opening70 in theside wall66. In one embodiment, thecircumferential opening70 extends approximately one-half inch in length along its longitudinal axis, although the size of this opening could vary depending upon the dimensions of the targeted bone and the size of the expandable structure. Thecircumferential opening70 is sized to accommodate anexpandable structure86. Thecircumferential opening70 desirably also allows a fillingmaterial99 to be placed near and/or into the fracture site.
• FIG. 8A depicts one alternate embodiment of a fracture reduction cannula18A constructed in accordance with the teachings of the present invention. Because many of the disclosed components are similar to those previously described, like reference numerals will be used to denote similar components. In this embodiment, thedistal end44A of the cannula18A is not solid, but rather extends along the side wall66A, with one or more longitudinally extendingteeth120 disposed at thedistal end44A.
• E. The Handle
• Thehandle13, which can be made from a molded or cast rigid plastic or metal material, is more fully described in U.S. application Ser. No. 09/014,229, filed on Jan. 27, 1998, the disclosure of which is incorporated herein by reference. As shown inFIG. 14, the handle has a smoothupper side17. Itslower side29 containsrecesses15 and19. The flanged surfaces of theobturator instrument12, thedrill bit instrument16, thepercutaneous cannula14, and thefracture reduction cannula18 mate with thehandle13.Recess15 is adapted to accept theobturator12 and thedrill bit instrument16 whilerecess19 is adapted to accept thefracture reduction cannula18. If desired, another recess can be provided (not shown) sized to accept thepercutaneous cannula14 in a similar manner.
• F. The Bone Compaction and/or Displacement Instrument
• FIG. 11 shows aninstrument80 for accessing bone for the purpose of compactingcancellous bone36 and/or displacingcortical bone38. Theinstrument80, and instructions for assembling same, are more fully set out in U.S. application Ser. No. 09/420,529, filed on Oct. 19, 1999, incorporated herein by reference.
• Theinstrument80 includes acatheter tube assembly82, as shown inFIG. 11. Thedistal end84 of thecatheter tube assembly82 carries anexpandable structure86. In use, theexpandable structure86 is deployed and expanded inside bone, e.g., in theradius20 as shown inFIGS. 20, 21, and22, to compactcancellous bone36 and/or displacecortical bone38, as will be described later.
• As further shown inFIG. 11, theinstrument80 includes anouter catheter body88, and aninner catheter body90 which extends through theouter catheter body88. The proximal ends92 of the outer88 and inner90 catheter bodies are coupled to a y-shaped adaptor/handle94. The y-shaped adaptor/handle94 carries afirst port96 and asecond port98 at itsproximal end92. Thefirst port96 is adapted to be coupled with aninflation syringe101, thesyringe101 in the present case being used to deliver a pressurized liquid into theexpandable structure86. Thesecond port98 is adapted for insertion of a stiffening stylet (not shown) to facilitate. insertion of thedistal end84 of theinstrument80.
• AsFIG. 11 shows, theexpandable structure86 is coupled at its proximal end95 to the distal end93 of theouter catheter body88. Likewise, theexpandable structure86 is coupled at itsdistal end87 to thedistal end84 of theinner catheter body90.
• Theouter catheter body88 defines an interior bore, through which theinner catheter body90 extends. The interior bore, in use, conveys a pressurized liquid, e.g., a radio-opaque solution such as CONRAY® solution, or another fluid into theexpandable structure86 to expand it.
• The material from which theexpandable structure86 is made should possess various physical and mechanical properties to optimize its functional capabilities to compactcancellous bone36, and to movecortical bone38. Desirably, theexpandable structure86 has the capability to movecortical bone38 from a fractured condition to a pre-fractured or other desired condition, or both. The three most important properties ofexpandable structure86 are the ability to expand its volume; the ability to deform in a desired way when expanding and assume a desired shape inside bone; and the ability to withstand abrasion, tearing, and puncture when in contact withcancellous bone36.
• The desired properties for the structure material, and the description for creating a pre-formed structure, are more fully set out in U.S. application Ser. No. 09/420,529, filed on Oct. 19, 1999.
• As shown inFIG. 11, theexpandable structure86 carries radio-opaque markers91 located at adistal end102 and at aproximal end104 of segmented shapedregions100 of theexpandable structure86. The radio opaque markers91 function to indicate, under fluoroscopic or other real-time monitoring, the location of the segmented shapedregions100 in relation to thecircumferential opening70 of thefracture reduction cannula18.
• FIG. 12 illustrates the expandable structure in a collapsed state (solid lines) and an expanded state (broken lines).
• G. The Pin
• One or more conventional smooth Steinman pins130 or Kirschner (“K”) wires may be provided to assist in aligning and/or stabilizing fracture fragments, as will be described in greater detail later.
• H. The Filling Material Instruments
• The fillingmaterial99 instruments include a tamp81 as shown inFIG. 13, and a standard syringe. The fillingmaterial99 is introduced through the syringe and into thefracture reduction cannula18. Residual fillingmaterial99 may be urged through thefracture reduction cannula18 by employing the tamp81, as will be described in greater detail later.
• I. The Kit
• As shown inFIG. 4, akit200 is provided, includinginstruments12,13,14,16,18,80, and81. Thekit200 and the instruments contained therein are sterile and are sealed until an instance of use.
• IV. Illustrative use of the System
• The size and shape of the access tools and/or expandable structure(s)86 to be used, and the amount of bone to be moved, are desirably selected by the physician, taking into account the morphology and geometry of the site to be treated. The shape of the joint, the bones and soft tissues involved, and the local structures that could be harmed if moved inappropriately, are generally understood by medical professionals using textbooks of human anatomy along with their knowledge of the site and its disease and/or injury. The physician is also desirably able to select the desired shape and size of theexpandable structure86, thecavity35 and their placement based upon prior analysis of the morphology of the targeted bone and joint using, for example, plain film x-ray, fluoroscopic x-ray, or MRI or CT scanning. The shape, size and placement are desirably selected to optimize the strength and ultimate bonding of the fracture relative to the surrounding bone and/or tissue of the joint.
• In a typical procedure, a patient is placed under local anesthesia, although general anesthesia may instead be employed. Where afracture34 is that of adistal radius24, a physician makes an incision of approximately one (1) centimeter on the radial aspect of thedistal radius24. In an alternate embodiment, one may access thedistal radius24 by an approach through theulna26. The distance between the incision and thefracture34 is approximately 0.5 centimeter. Of course, while the present procedure is described in the context of a minimally invasive surgery, various other surgical approaches, including percutaneous, subcutaneous, non-open, partially open and/or completely open surgical approaches may be utilized in accordance with the teachings of the present invention.
• After making the incision, the physician spreads the soft tissue by using a small clamp designed to avoid injury to nearby nerves, muscles, and vasculature. The physician then acquires theobturator instrument12 and thehandle13. Theobturator instrument12 may have at its proximal end42 aflanged surface52 that mates with arecess15 within thehandle13. Use of thehandle13 with theobturator instrument12 will produce axial as well as radial movement, as shown in U.S. application Ser. No. 09/014,229, filed on Jan. 27, 1998. The physician then fits theproximal end42 of theobturator instrument12 intorecess15 in thehandle13, as shown inFIG. 15.
• The physician next twists thehandle13 while applying longitudinal force to thehandle13. In response, the tapered surface of theobturator instrument12 rotates and penetrates soft tissue through the incision, as shown inFIG. 15a.The physician may also tap thehandle13, or otherwise apply appropriate additional longitudinal force to thehandle13, to advance theobturator instrument12 through soft tissue.
• Under fluoroscopic monitoring or other real-time monitoring, the physician advances theobturator instrument12 through soft tissue down to thedistal radius24, asFIG. 15ashows. Theobturator instrument12 is inserted distal to proximal from the radial side of theradius20 to the ulnar side of theradius20. Theobturator instrument12 is introduced into theradius20. Desirably, theobturator instrument12 is introduced at an angle between minus 10 degrees and 45 degrees to the radio-carpal joint. More desirably, theobturator instrument12 is introduced at an angle between zero degrees and 30 degrees to the radio-carpal joint. Most desirably, theobturator instrument12 is introduced at an angle equal to the angle of the radio-carpal joint, i.e., approximately 23 degrees. Of course, if desired, the physician may utilize various other approach paths to access the bone, including a dorsal approach.
• The physician next removes thehandle13 from theobturator instrument12 and places theproximal end42 of thepercutaneous cannula14 in arecess19 in thehandle13. The physician slides thepercutaneous cannula14 over theobturator instrument12,distal end44 first. The physician then twists thehandle13 while applying longitudinal force to thehandle13, in order to seat thepercutaneous cannula14 against and/or into the externalcortical bone38, as shown inFIG. 16. Once thepercutaneous cannula14 is seated in thecortical bone38, theobturator instrument12 is removed,proximal end42 first.
• In an alternate embodiment, instead of using theobturator instrument12 to access externalcortical bone38, the physician may instead insert a conventional spinal needle, the needle having an outer sheath and a stylus, into the bone. Upon puncturing the bone, the physician removes the stylus and inserts aguide pin108 through the outer sheath. The sheath is then removed and thefracture reduction cannula18 is deployed over theguide pin108. The physician then fits theproximal end42 of thepercutaneous cannula14 into arecess19 in thehandle13 and slides the assembly,distal end44 first, over thefracture reduction cannula18, as shown in FIG.28. Subsequently, theguide pin108 is removed, proximal end first.
• After removing theobturator instrument12, or theguide pin108 as in the case of the alternate embodiment described above, thehandle13 is removed from thepercutaneous cannula14. As shown inFIG. 15, theproximal end42 of adrill bit instrument16 is then placed in a recess in thehandle13. The preferred size of thedrill bit16 is 3.2 millimeters. The physician slides the drill bit assemblydistal end44 first through thebore60 of thepercutaneous cannula14. Using manual pressure, thedrill bit instrument16 is advanced down to and into thedistal radius24. As an alternate embodiment, instead of using manual pressure, the physician could connect theproximal end42 of thedrill bit instrument16 to a conventional motor-driven drill. The physician directs thedrill bit instrument16 to penetrate thecortical bone38 and thecancellous bone36 of thedistal radius24, as shown inFIG. 17.
• After drilling throughcortical bone38 and intocancellous bone36, the physician removes thedrill bit instrument16 from thehandle13. Thefracture reduction cannula18 is then inserted,distal end44 first, into the bore of thepercutaneous cannula14, as shown inFIG. 18. Thedistal end44 of thefracture reduction cannula18 extends beyond thedistal end44 of thepercutaneous cannula14. In an alternate embodiment, the physician may at this point remove thepercutaneous cannula14, leaving only thefracture reduction cannula18 in place. In one embodiment, it is preferred to employ afracture reduction cannula18 that hasscrew threads71 on itsdistal end44 as shown inFIG. 9, thereby enabling thefracture reduction cannula18 to be anchored to an interior surface ofcortical bone38 in response to rotation of thefracture reduction cannula18, e.g., by using thehandle13. In an alternative embodiment (seeFIG. 8B), the physician may employ afracture reduction cannula18 that has a blunt, tapereddistal end44 instead ofscrew threads71 on thedistal end44. If such afracture reduction cannula18 is employed, the physician may choose to drill a hole incortical bone38 in which to seat the blunt, tapereddistal end44. Desirably, if thedistal end44 is blunt and tapered, thefracture reduction cannula18 may be adapted to rotate independently from thedistal end44. As another alternative, a cannula18A as depicted inFIG. 8A could be inserted into the targeted bone as previously described, with theteeth120 anchoring thedistal end44A of the cannula18A to the cortical wall (not shown) of the targeted bone region. With this embodiment, it would not be necessary to drill a hole through the cortical wall to anchor the distal end44aof the cannula18A.
• In another embodiment, the access path can be made directly through the one or more fracture lines in the targeted bone. Such an arrangement minimizes trauma to the fractured bone (by reducing additional damage to healthier sections of the bone) and permits the creation of acavity35 which extends to each side of the fracture line.
• Thefracture reduction cannula18 is placed into thecancellous bone36 of thedistal radius24 such that thecircumferential opening70 is facing towards the fracture, as shown inFIG. 18. Thefracture reduction cannula18 is checked radiologically to ensure that thecircumferential opening70 is contained entirely within thecancellous bone38 of theradius20. In one embodiment, one or more markings (not shown) can be provided on theproximal end42 of thecannula18, allowing the physician to visually gauge the orientation of thecannula18. In one embodiment, thefracture reduction cannula18 is approximately 3 to 4 inches in length.
• The physician can now acquire thecatheter tube assembly82 for placement into thebore68 of thefracture reduction cannula18. In one embodiment, the uninflatedexpandable structure86 carried by the catheter tube measures12 millimeters in length from its proximal end to its distal end, althoughstructures86 of varying lengths could be used, includingexpandable structures86 of 15 mm or 20 mm, depending upon the size of the patient, the size and location of thefracture34, the size of theopening70 and thecavity35 size and shape and/or displacement of bone desired. Thecatheter tube assembly82 is now introduced into thebore68 of thefracture reduction cannula18.
• The physician guides thecatheter tube assembly82 through thefracture reduction cannula18 until theexpandable structure86 enters and lies adjacent to thecircumferential opening70 of thefracture reduction cannula18, as shown inFIG. 20. In one embodiment, thedistal end44 of thefracture reduction cannula18 is solid, as shown inFIG. 9, thus preventing anexpandable structure86 from emerging from thedistal end44 of thefracture reduction cannula18. The placement of theexpandable structure86 within thecircumferential opening70 can be determined by radio opaque markers91 located on theexpandable structure86, as shown inFIG. 11. Theexpandable structure86 is passed into bone through thefracture reduction cannula18 in a normally collapsed and non-inflated condition. Theexpandable structure86 is now aligned withcancellous bone36.
• The physician, after verifying that theexpandable structure86 is adjacent thecircumferential opening70, conveys a pressurized fluid, such as a radio opaque fluid, through thecatheter tube assembly82 and into theexpandable structure86. Theexpandable structure86 now expands intocancellous bone36, as shown inFIG. 21. Thefracture reduction cannula18 desirably directs the expandingstructure86 towards thefracture34. Progress of theexpandable structure86 is evaluated both on A-P, or anterior-posterior, and lateral x-rays. Preferably, the A-P x-ray is used until thedistal end24 of theradius20 begins to move, at which point both A-P and lateral views are obtained. The pressurized fluid is used to inflate theexpandable structure86 and expand it through thecircumferential opening70 in order to compresscancellous bone36 and/or displacecortical bone38. Theexpandable structure86 will desirably form aninterior cavity35 in thecancellous bone36, as shown inFIG. 24. Desirably, the compressedcancellous bone36 will seal anyfractures34 and/or cracks in the targeted bone through which the fillingmaterial99, to be described later, can flow out of the targeted treatment area.
• The compression ofcancellous bone36, as shown inFIG. 22, can also exert an interior force upon the surroundingcortical bone38. The interior force will elevate or push broken and compressed bone back to or near its original pre-fracture, or other desired, condition. Once thefracture34 is well aligned, it is preferred to introduce one or more smooth “Steinman” pins130 or K-wires proximal to the joint surface of theradius20 and distal to the inflatedexpandable structure86. Thepins130 can be placed across thedistal end24 of theradius20 and into thedistal ulna30, as shown inFIGS. 22 and 24-27. Alternatively, the pin(s)130 can be secured into theradius20 without penetrating theulna26. Thepin130 desirably prevents thefracture34 from displacing upon further manipulation of the wrist and/or contraction of theexpandable structure86. If desired,additional pins130 can be used to manipulate and/or secure other cortical bone fragments, or can be used to further secure a single bone fragment.
• In one or more alternate embodiments, thepins130 can be introduced once a bone fragment has been displaced to a prior position, but prior to completion of the inflation steps. For example, where inflation of the balloon displaces a fragment to a desired position, but addition cavity creation is desired, the fragment may be secured in position using one ormore pins130, and then the balloon can be further inflated to create alarger cavity35 and/or compress additionalcancellous bone36.
• As shown inFIG. 23, in one preferred embodiment, the patient's fingers of the affected arm can be placed in horizontal finger traps132, with the patient's palm facing the treatment table. A rolledtowel133 may be placed under the patient's wrist. By grasping the finger traps132 and gently pulling on them, the physician can extend the patient's arm and thus reduce any pressure that may be exerted at the fracture site. This approach potentially allows for an improved correction of the volar tilt (15 degrees) of thedistal radius24. If desired, this can be accomplished prior to, during or after fracture reduction has been accomplished.
• Once theinterior cavity35 is formed and any desiredpins130 set in place, theexpandable structure86 is collapsed and thecatheter tube assembly82, with the collapsedexpandable structure86, is removed. As shown inFIG. 27, thecavity35 is now in a condition to receive a fillingmaterial99 through thefracture reduction cannula18. The fillingmaterial99 can be any of a number of available bone filling materials, which include, but are not limited to, resorbable and/or remodelable bone cements, calcium phosphates, allograft tissue, autograft tissue, poly(methylmethacrylate) or Norian SRS□ bone matrix. The filling material may be introduced into the fracture reduction cannula by means of a syringe (not shown). The fillingmaterial99 progresses through thefracture reduction cannula18 and into thecircumferential opening70 of thefracture reduction cannula18. The fillingmaterial99 desirably provides improved interior structural support forcortical bone38. Desirably, the fillingmaterial99 extends proximal to any cortical defects created by thedrill bit instrument16 and by thefracture reduction cannula18. In one embodiment, approximately two (2) to seven (7) cubic centimeters of fillingmaterial99 can be injected into thecavity35.
• After the fillingmaterial99 is introduced, a tamp81 may be inserted into thefracture reduction cannula18 as shown inFIG. 26, for the purpose of urgingresidual filling material99 into theinterior cavity35. Tamping of the fillingmaterial99 may also cause the material to interdigitate into the surroundingcancellous bone36, further supporting the cancellous36 andcortical bone38. Thefracture reduction cannula18 and (if still present) thepercutaneous cannula14 are removed. If desired, any void remaining subsequent to removal of thecannula18 can be filled with fillingmaterial99. The patient should be kept immobile for ten to fifteen minutes. After the immobilization, the pin(s)130 and finger traps132 can be removed and the hand of the patient is checked for motion. The entry site is covered with appropriate antibiotics and an adhesive strip is applied.
• FIGS. 21A and 22A depict an alternate embodiment in which theexpandable structure86 is expanded within the fractured bone to create acavity35 which extends across at least one fracture line in the bone. In this embodiment, the fillingmaterial99 ultimately introduced into thecavity35 can extend across the fracture line and desirably interdigitate into the cancellous bone of the fragmented section(s). This will desirably anchor the fractured sections to the bone, thereby permitting the bone to undergo significant distractive and/or torsional loading without slippage along the fracture line(s) and/or subsequent re-fracture of the treated bone.
• If desired, the disclosed systems and methods could be used with equal utility in reducing and/or reinforcing fractures in bones of younger individuals and/or individuals not having osteoporosis. In such patients, the present systems and methods would allow for an immediate resumption of activity, reducing the opportunity for degradation of adjacent joints and promoting healing of the fracture.
• The features of the invention are set forth in the following claims.

Claims (14)

1. A tool for establishing a percutaneous path into bone comprising:

a cannula having a side wall defining an internal bore aligned along an axis, the cannula having a distal end;

a circumferential opening in the side wall, the circumferential opening having a distal terminus, and the circumferential opening extending partially about the side wall and being elongated along the axis and adapted to accommodate passage of an expandable structure from within the bore; and

the bore being solid between the distal terminus of the circumferential opening and the distal end of the cannula.

2. A tool for establishing a percutaneous path into bone comprising:

a cannula having a side wall defining an internal bore aligned along an axis, the cannula having a distal end;

a distal opening in the distal end communicating with the bore to accommodate passage of a guide pin; and

a circumferential opening in the side wall, the circumferential opening extending partially about the side wall and being elongated along the axis and adapted to accommodate passage of an expandable structure from within the bore.

3. A tool for establishing a percutaneous path into bone comprising:

a cannula having a side wall defining an internal bore aligned along an axis, the cannula having a distal end;

a circumferential opening in the side wall, the circumferential opening extending partially about the side wall and being elongated along the axis and adapted to accommodate passage of an expandable structure from within the bore; and

a surface on the distal end of the cannula to anchor the distal end in bone.

4. A tool as inclaim 3, wherein the circumferential opening has a distal terminus; and

the bore being solid between the distal terminus of the circumferential opening and the distal end of the cannula.

5. A tool as inclaim 3, wherein the cannula has a distal opening in the distal end communicating with the bore to accommodate passage of a guide pin.

6. An assembly for treating bone comprising:

a cannula having a side wall defining an internal bore aligned along an axis, the cannula having a distal end;

a distal opening in the distal end communicating with the bore to accommodate passage of a guide pin;

a circumferential opening in the side wall extending partially about the side wall and being elongated along the axis and adapted to accommodate passage of an expandable structure from within the bore; and

an expandable structure adapted for insertion through bone into the cannula and expansion through the circumferential opening.

7. An assembly for treating bone comprising:

a cannula having a side wall defining an internal bore aligned along an axis, the cannula having a distal end;

a circumferential opening in the side wall, the circumferential opening having a distal terminus, and the circumferential opening extending partially about the side wall and being elongated along the axis and adapted to accommodate passage of an expandable structure from within the bore;

the bore being solid between the distal terminus of the circumferential opening and the distal end of the cannula; and

an expandable structure adapted for insertion through bone into the cannula and expansion through the circumferential opening.

8. An assembly for treating bone comprising:

a cannula having a side wall defining an internal bore aligned along an axis, the cannula having a distal end;

a circumferential opening in the side wall, the circumferential opening having a distal terminus, and the circumferential opening extending partially about the side wall and being elongated along the axis and adapted to accommodate passage of an expandable structure from within the bore;

a surface on the distal end of the cannula to anchor the distal end in bone; and

an expandable structure adapted for insertion through bone into the cannula and expansion through the circumferential opening.

9. An assembly as set forth inclaim 6 or7 or8, wherein the expandable structure has radio opaque markers for locating the structure within the circumferential opening.

10. A method for treating bone comprising the steps of:

providing a cannula as defined inclaim 1 or2 or3;

inserting the cannula into cancellous bone;

inserting an expandable structure through the cannula into registration with the circumferential opening; and

expanding the expandable structure through the circumferential opening into contact with cancellous bone.

11. A method according toclaim 10, wherein the step of expanding the expandable structure compacts cancellous bone.

12. A method according toclaim 11, wherein the compaction of cancellous bone forms a cavity.

13. A method according toclaim 12 and further including the step of conveying a material into the cavity.

14. A method according toclaim 10 wherein the step of expanding the expandable structure moves fractured cortical bone.

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