US20060235383A1 - External fixator - Google Patents

Abstract

A fixator for use in the reconstruction of acute, chronic and traumatic injuries to the upper and lower extremities. The fixator has a unique clamping system that allows for the snapping in of pins and rails, and for multi-planar fixation of bones.

Description

FIELD OF THE INVENTION
• The present invention relates generally to external fixation devices, and more particularly to an external fixation device for use in the reconstruction of acute, chronic and traumatic injuries to the upper and lower extremities.
BACKGROUND OF THE INVENTION
• In the medical field, patients can suffer from acute, chronic, and/or traumatic injuries to the upper and lower extremities. In such circumstances, it is often desirable to stabilize and reconstruct the bones of the afflicted area. To that end, systems have been developed to help stabilize and reconstruct injured bones. One type of system employed in the past is an external fixation system.
• All bone injuries are not the same. As a result, the best mode of treatment for a bone injury can vary significantly depending on the size of the person, size of the injured bone, and type of bone injury. Specifically, it is often times desirable to have an external fixation device that is capable of accommodating a wide variety of pin placements. However, it is simultaneously desirable to have a relatively simple system that can be readily taught to practitioners in the field. Further, it is also necessary to have a stable system that effectively treats the bone injury. Finally, it is desirable to have a cost effective system. It is therefore desirable to have an external fixation device that allows for versatile pin placement, is relatively simple, stable, and cost effective.
SUMMARY OF THE INVENTION
• The present invention comprises an external fixation device (“fixator”) for use in the reconstruction of acute, chronic and traumatic injuries to the upper and lower extremities. The fixator's functions include, but are not limited to, immobilization, compression, joint realignment, arthrodesis, bone distraction and lengthening, fracture reduction/stabilization, and treatment of Charcot arthropathy. More specifically, potential uses for the fixator include acute stabilization and chronic reconstruction of bones, particularly those of the hand or foot. Advantages of using the fixator include, but are not limited to, the ability to gradually correct over time, to fixate away from the injury site if necessary, to provide additional manipulation or additional correction, and to provide assistance in interpositional bone grafting.
• The fixator can be used in multi-planar and multi-joint correction, is percutaneous and, therefore, minimally invasive, and can provide additional stability and mobility when compared to fixation devices currently in use. Additional advantages of the present invention over existing devices include the design and adjustability to easily assemble and disassemble components of the system without disturbing pins already set into the patient's bone or the rest of the system itself.
BRIEF DESCRIPTION OF THE DRAWINGS
• The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The drawings may not be to scale. The invention may best be understood by reference to the following description taken in conjunction with the accompanying drawings, in the several figures of which like reference numerals identify like elements, and in which:
• FIG. 1 is a side perspective view of one embodiment of the fixator.
• FIG. 2 is a side perspective view of a second embodiment of the fixator.
• FIG. 3 is a side and top view of one embodiment of a clamp system.
• FIG. 4 is a side view of one embodiment of the fixator.
• FIG. 5 is a top view of one embodiment of the fixator.
• FIG. 6 is an angled view of one embodiment of parts of the clamp system.
• FIG. 7 is a side view of one embodiment of the clamp system.
DETAILED DESCRIPTION OF THE INVENTION
• While the present invention is susceptible of embodiments of various forms, there is shown in the drawings, and will hereinafter be described some exemplary and non-limiting embodiments, with the understanding that the present disclosure is to be considered an exemplification of the invention. It is not intended to limit the invention to the specific embodiments listed.
• As can be seen inFIGS. 1-7, in one embodiment of the present invention, afixator10 comprises arail12, at least oneclamp system14, and apin16. Generally, theclamp system14 is configured to attach to both therail12 and thepin16, which is connected to thebone40 for fixation and stabilization. Thefixator10 may further include compression anddistraction nuts18 functionally connected to thefixator10 to allow for additional manipulation of bone healing and growth. Theclamp systems14 can be splined to receive and holdrails12 andpins16.
• Therails12 may be any size or shape, and persons of skill in the art will recognize that different application requirerails12 of many differing sizes or shapes, all of which are contemplated herein. Therails12 may, for example, have a circular, oblong, square, rectangular, or other-shaped cross section. Typically, however, therails12 have a round or circular cross-section and are sized in a manner suitable for fixation ofsmall bones41, such as those of the foot or hand. Therails12 may be composed of many materials including, for example, carbon fiber or high density plastic, which allows the rod to be radiolucent. Optionally, therails12 may also be threaded to allow for attachment ofclamp systems14, distraction/compression nuts18, or other components of afixator10.
• In one embodiment of the present invention, therail12 has a “negative” thread pattern, in which the threads22 are grooves in the surface of therail12 rather than protrusions. In this specification, reference to a threaded component will be a disclosure of both a positive and negative thread. The negative thread pattern allows, for example, theclamp system14 to easily slide up and down therail12, while still allowing for the attachment ofcompression nuts18 or other components which could be threaded onto therail12. In such situations, the corresponding component, such as acompression nut18, will have a positive thread pattern. In a preferred embodiment, therail12 has a thread pitch of approx 1 mm so one revolution of around the threadedrail12 produces 1 mm of linear movement. In another embodiment, therail12 can be geared. In such an embodiment, the rail has a rack andpinion design20 that allows for compression or distraction. This geared version can have ascale24 indicating the amount of compression or distraction.
• As can be seen more specifically inFIGS. 6 and 7, in a preferred embodiment, theclamp system14 comprises afirst clamp area32 and asecond clamp area42. Preferably, thefirst clamp area32 comprises apin clamp34 while thesecond clamp area42 comprises a rail orbar clamp44. Preferably, thefirst clamp area32 is functionally connected to thesecond clamp area42 such that the object held by the different clamp areas, eitherpins16 orrails12, can lie in different planes.
• Preferably, thefirst clamp area32 is apin clamp34 that can comprise apin clamp top36, apin clamp bottom38 and afirst clamp bolt40. Thepin clamp top36 andbottom38 are each configured to allow thefirst clamp bolt40 to pass through them. In one embodiment, thefirst clamp bolt40 is threaded, and thepin clamp top36 andpin clamp bottom38 have internal, threaded holes configured to receive the threadedfirst clamp bolt40. When held by thefirst clamp bolt40, thepin clamp top36 andbottom38 can be thought of as a set that together define at least onepin passage33 capable of receiving thepin16. Preferably, the pin clamp top andbottom36,38 each haveinner surfaces35 that together define twodistinct pin passages33 each capable of receiving thepin16. It is preferred that theinner surfaces35 of thepin passages33 be textured to allow for more secure engagement of thepin16. For example, theinner surfaces35 may have a 2× diamond face withgrooves 90 degrees to each other. In addition to theinner surfaces35 being textured, other surfaces of the pin clamp top andbottom36,38 may be textured where a more secure engagement is desired.
• In one embodiment, the twodistinct pin passages33 are configured to receive thesame size pin16. In another embodiment, onepin passage33 is configured to receive onesize pin16, for example a half pin, while theother pin passage33 is configured to receive asecond size pin16, for example a transfixing pin. It is contemplated that thepin passage33 will extend in a direction substantially perpendicular to thefirst clamp bolt40. In one embodiment, the pin clamp top and bottom36,38 can be rotated around thefirst clamp bolt40 such that thepins16 can be orientated in any direction in the plane perpendicular to thefirst clamp bolt40.
• In a preferred embodiment, thefirst clamp area32 further comprises anotherpin clamp34 or arail clamp44. An example of afirst clamp area32 with at least two pin clamps can be found inFIG. 7. As can be seen inFIG. 7, two sets of pin clamp top and bottom clamps36,38 can be arranged proximate each other on thepin clamp bolt40. In such a set up, fourdistinct pin passages33, each capable of receiving apin16, can be defined by the pin clamp top andbottoms36,38. In a preferred embodiment, thefirst clamp area32 further comprisessprings46 which are functionally attached to thefirst clamp area32 and that exert pressure on some of the pin clamp tops andbottoms36,38. In such a configuration, the pin clamps34 can be “snap in.” That is, one can exert force on the pin clamp top and/or bottom36,38. When so doing, the pin clamp top and/or bottom36,38 will push against thesprings46 and thereby be in a position that defines anopening48 leading into thepin passage33 capable of allowing thepin16 to be pressed into thatpin passage33. When the force is released, thesprings46 again exert full pressure on the pin clamp top and/or bottom36,38, causing the pin clamp top and bottom36,38 set to clamp on thepin16 and hold it in a fixed position. In addition, anut52 can then be tightened to more securely hold therail12 orpin16 in place.
• In another embodiment, the first clamp area further comprises arail clamp44. Therail clamp44 comprises arail clamp top46, a rail clamp bottom47 and arail clamp bolt49. The rail clamp top and bottom46,47 are each configured to allow therail clamp bolt49 to pass through them. In one embodiment, therail clamp bolt49 is threaded, and the rail clamp top and rail clamp bottom46,47 have internal, threaded holes configured to receive the threadedrail clamp bolt49. When held by therail clamp bolt49, the rail clamp top and bottom46,47 can be thought of as a set that together define at least onerail passage54 capable of receiving therail12. It is contemplated that theinner surfaces56 of therail passage54 can be textured to allow for more secure engagement of therail12. For example, theinner surfaces56 may have a 2× diamond face withgrooves 90 degrees to each other. In addition to theinner surfaces56 being textured, other surfaces of the rail clamp top and bottom46,47 may be textured where a more secure engagement is desired. As seen inFIG. 5, thefirst clamp area32 can comprise arail clamp44 and apin clamp34. In such cases, therail passage54 can be in a different plane than thepin passage33. Thefirst clamp area32 can be configured to allow for therail12 in therail passage54 to be disposed in a different direction than thepin16 in thepin passage33. For example, thepin16 may extend at an angle generally perpendicular to the bone orbones41 to be fixed so that it can be anchored in thebone41 while therail12 may extend at an angle generally parallel to the bone orbones41 to be fixed.
• In one embodiment, ahinge60 is attached to thefirst clamp bolt40 proximate to either a pin or rail clamp bottom38,47. In a preferred embodiment, thehinge60 has amale element62 and afemale element64. The use of the terms male andfemale elements62,64 is not meant to suggest a certain structure, but only to disclose that the two elements are configured to work together to provide a hinged connection. Themale element62 has afirst section66 and asecond section68 that are connected to each other. The first section and thesecond section66,68 can be disposed at about a 90 degree angle in relation to each other. Preferably, thefirst section66 is configured to receive thefirst clamp bolt40 by having a hole therethrough. The hole may be threaded. It is also preferred that thesurface69 of thefirst section66 proximate thepin clamp34 be textured. For example, the surface may have a 2× diamond face withgrooves 90 degrees to each other. Preferably, the second section28 is configured to receive ahinge bolt70 by having a hole therethrough. The hole may be threaded.
• Thefemale element64 can have afirst section72 that is connected to asecond section74, preferably at about a 90 degree angle in relation to each other. Thefirst section72 of thefemale element64 is preferably configured to receive arail clamp bolt49 by having a hole therethrough. Thesecond section74 of thefemale element64 can have a hole therethrough that is able to accommodate thehinge bolt70. Thefemale element64 is hingedly connected to themale element62. In a preferred embodiment, both thefemale element64 and themale element62 are disposed on thehinge bolt70, and are held thereon by a hinge retaining washer ornut76. When thehinge bolt70 and retaining washer or not76 are loose, thefemale element64 can be rotated in relation to themale element62, and vice versa. To stabilize the connection, thehinge bolt70 is tightened, thus holding themale element62 against thefemale element64. Thesurfaces78 of the female andmale elements62,64 that come into contact with each other may be textured to increase friction and create a more stable connection. In addition,washers80 may be employed to ensure a stable connection.
• In a preferred embodiment, thefirst clamp area32 is connected via thehinge60 to thesecond clamp area42. Thesecond clamp area42 can comprise apin clamp34, arail clamp44, or a combination of pin and rail clamps,32,44. Preferably, eachclamp system14 allows for multi-planar attachment ofrails12 and pins16.
• In another embodiment, theclamp system14 comprises one clamp area. In such a system, the one or more pin clamps32 and one or more rail clamps34 can be linearly attached to thesame bolt82. For example, as can be seen inFIG. 3, such a clamp system comprises one or more pin clamp tops36 held in spaced relation to one or more correspondingpin clamp bottoms38. Together, the pin clamp top and bottom36,38 define apin passage33 that can accept apin16. The pin clamp tops andbottoms36,38 are configured with a hole therethrough that accepts apin clamp bolt82. The pin clamp tops andbottoms36,38 can be loosened and tightened to accept apin16 and then securely attach to thatpin16. This embodiment of aclamp system14 further comprises aclamp body84 that preferably is configured with a hole therethrough that can accept thepin clamp bolt82. Theclamp body84 can further define arail passage86 that is capable of accepting arail12. Theclamp body84 can further comprises a device, such as abar clamp bolt88, that is capable of being screwed into therail passage86 to secure therail12.
• Thepins16 can be half pins or transfixing pins. In practice, one part of thepin90 is set into a patient's bones while a second part of thepin92 is attached to aclamp area32,42. The configuration of thefixator10 allows forsuch pins16 to be placed prior to, during, or after assembly of the other parts of thefixator10 without comprising the accuracy of the fixation.
• As can be seen inFIGS. 1, 2,4, and5, it is contemplated that thefixator10 comprise more than oneclamp system14. Afirst clamp system14 is preferably attached to abone41 at a first location. Asecond clamp system14 is preferably attached to abone41, either the same bone, or a different bone, at a second location. The twoclamp systems14 are connected by arail12, to which bothclamps systems14 are attached via therail clamp44. More than oneclamp system14 and more than onerail12 can be utilized. In one embodiment, afirst clamp system14 has arail clamp44 attached to afirst rail12 and apin clamp34 attached to twopins16. Thepins16 are attached to abone41 at a first location. Asecond clamp system14 has arail clamp44 attached to thefirst rail12, and apin clamp34 attached to twodifferent pins16, which are attached to abone41 at a second location. Thesecond clamp system14 also has asecond rail clamp44 attached to asecond rail12. Athird clamp system14 has arail clamp44 attached to thesecond rail12 and apin clamp34 attached to twopins16. These twopins16 are attached to either thesame bone41, or a different bone. As can be seen, thefixator10 described herein, with eachclamp system14 capable of being comprised of one or more adjustable rail or pin clamps44,34, allows for a wide range offixator10 configurations that allow for effective treatment of a number of injuries.
• Theclamps systems14 are adjustable with respect to therail12 in that eachclamp system14 can slide up or down therail12 and also rotate around therail12 freely. Once the optimum position for eachclamp system14 is obtained, theclamp system12 may then be fixed securely in place by simply tightening therail clamp44. Moreover,additional clamp systems14 may be added to or removed from thefixator10 easily, both prior to fixation and stabilization and at any point during the healing process, and any number of rail or pin clamps44,34 may be used, depending upon the number of rails or pins12,16 necessary for a given treatment.
• Thepins16 can be placed independently of thefixator10 because of the snap-in functionality of theclamp systems14 and the ability of thefixator10 to correct in all planes due to the multi-planar movement of theclamp systems14.
• In a further embodiment of the present invention, compression nuts anddistraction nuts18 can attached to therails12 and used in conjunction with theclamp systems14 to further adjust bone healing and growth. The nuts18 may be used to move theclamp systems14 incrementally along therail12 without moving thepins16 or other components of thefixator10, thus providing additional correction on a minute scale during the healing or growth process. Thecompression nuts18 are preferably attached on therail12 such that, when moved, they will force twoclamp systems14 to move closer to each other. The distraction nuts18 are preferably attached on arail12 between twoclamp systems14 such that when thedistraction nut18 is moved, it will force oneclamp system14 away from the other. Preferably, more than one compression and ordistraction nuts18 can be attached to thesame rail12 to allow for compression or distraction, i.e., the movement of one or more than oneclamp systems14 in either direction along therail12. Optionally, the compression anddistraction nuts18 may have built in washers. Further, the compression anddistraction nuts18 may have a positive thread and can be used in conjunction with around rail12 having a negative thread, as described previously.
• In a further embodiment of the present invention, thefixator10 may be easily modified in many ways, such as for example to accommodatepins16 of multiple diameters and lengths. Additionally, many various sizes and shapes ofclamps systems14, rails12, and/or compression/distraction devices may be employed without detracting from the spirit of the invention.Clamp systems14, pins16, and rails12 can be easily reproduced, for example, for medium and large applications as well, such as for use on long bones of the leg or arm.
• Because of the exceptional adjustability of thefixator10, the fixator described herein can be connected to various parts of the foot or other body parts without being limited by the configuration of the device. Further, theclamp systems14 also have the mechanical ability to interconnect with other rails and fixation systems, allowing for multiple-rail systems or more complex applications.
• In further embodiments of the present invention, for example, the fixator can be used in conjunction with foot plate (“U ring”) attachments, wires, Ilizarov fixators, or any other compatible external fixator device (none of which are shown) through the use of pins, wires (not shown), and/or transfixing pins.
• Thefixator10 can be comprised of a wide variety of materials. In a preferred embodiment, the components of thefixator10 are composed of anodized aluminum, stainless steel, or composite polymer. Specifically, thepins16 can be manufactured from 316L stainless steel and are preferably 2 mm, 2.5 mm, or 3 mm in length.

Claims (20)

1. An fixator comprising:

at least one rail;

at least one pin suitable for use in bone fixation; and

at least one clamp system having a pin clamp, a rail clamp functionally connected by a hinge, wherein the pin clamp is capable of holding the pin in a first plane and the rail clamp is capable of holding the rail in a second plane; and the pin clamp is hingedly adjustable to the rail clamp.

2. The fixator ofclaim 1, wherein the rail is negatively threaded.

3. The fixator ofclaim 2, further comprising positively threaded nuts attached to the rail, the nuts being capable of pushing the clamp system along the rail.

4. The fixator ofclaim 3, wherein the pin clamp comprises a pin clamp bottom, a pin clamp top, wherein the pin clamp bottom and top together define at least one passage configured to receive the pin.

5. The fixator ofclaim 4, wherein the pin clamp further comprises at least one spring disposed such that when the spring is flexed it allows the pin clamp bottom or top to pivot and create an opening capable of receiving the pin.

6. The fixator ofclaim 5, wherein the pin clamp comprises two sets of pin clamp bottoms and tops, with each set defining one passage of a diameter to receive a first sized pin and a second passage of a second diameter to receive a second sized pin.

7. The fixator ofclaim 5, wherein the clamp system comprises at least two rail clamps.

8. The fixator ofclaim 5, wherein the rail clamp comprises a rail clamp bottom and a rail clamp top that together define at least one passage configured to receive the rail, wherein the rail clamp further comprises at least one spring disposed on the fixator such hat when the spring is flexed, it allows the rail clamp bottom or top to pivot and create and opening capable of receiving the rail.

9. The fixator ofclaim 5, wherein the fixator comprises at least two clamp systems attached to the same rail.

10. The fixator ofclaim 9, wherein the fixator comprises at least three clamp systems and at least two rails, wherein the first clamp system is attached to the first rail at a first location on that rail, the second clamp system is attached to the first rail at a second location on that rail and a second rail at a first location on that rail, and the third clamp system is attached to the second rail at a second location on that rail.

11. A clamp system for a fixator comprising:

a first clamp area comprises a pin clamp top and a pin clamp bottom attached to a pin clamp bolt, wherein the pin clamp top and pin clamp bottom that together define a pin passage and the pin clamp top and bottom can be flexed to allow for a pin to be snapped into the pin passage;

a hinge that is attached to the pin clamp bolt and hingedly connects the first clamp area to a second clamp area; wherein the hinge comprises a bolt assembly capable of fixing the first clamp area in a fixed position in relation to the second clamp area;

wherein the second clamp area comprises a rail clamp top and a rail clamp bottom that are attached to a rail clamp bolt, wherein the rail clamp top and rail clamp bottom together define a rail passage, and the rail clamp top and bottom can be flexed to allow for a rail to be snapped into the rail passage.

12. The clamp system for the fixator ofclaim 11, wherein both the first clamp area and second clamp area further comprise bolt assemblies capable of fixing the pin and rail into the pin and rail passages.

13. The clamp system for the fixator ofclaim 11, wherein the first clamp area further comprises a second pin clamp top and bottom attached to the pin clamp bolt, the second pin clamp top and pin clamp bottom together defining a second pin passage.

14. The clamp system for the fixator ofclaim 11, wherein the first clamp area further comprises a second rail clamp top and bottom that together define a second rail passage, and the second rail clamp top and bottom being flexible to allow for the second rail to be snapped into the rail passage.

15. An external fixation device comprising:

a rail;

at least one pin;

a first clamp and a second clamp, each clamp comprising a first spring-loaded component configured to attach the clamp to the rail, a second spring loaded component configured to attach to at least two pins, and a hinged component that can adjustably connect the first spring loaded component to the second spring loaded component, wherein both clamps are attachable to the same rail.

16. The external fixation device ofclaim 15, wherein the spring-loaded components are splined.

17. The external fixation device ofclaim 16, wherein at least one of the clamps has two or more spring-loaded components configured to attach the clamp to pins.

18. The external fixation device ofclaim 17, wherein the rail is negatively threaded.

19. The external fixation device ofclaim 18, wherein the device further comprises at least one nut that is capable of moving at least one clamp along the rail.

20. The external fixation device ofclaim 15 wherein the pins attached to the first spring-loaded component are anchored in a bone at a first location and the pins attached to the second spring-loaded component are anchored in a bone at a second location.

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