Balancer system for talar cut

Abstract

A balancer assembly (100) for a talar cut is provided. The assembly (100) includes a spreader (110) having a distal end, a balancer releasably attachable to the distal end of the spreader (110), and a rotational aligner (130) releasably attachable to the spreader (110). An alignment block (141) is attached to the rotational aligner (150); and a tibial aligner (130) is attached to the alignment block (141).

Description

TITLE OF THE INVENTION Balancer System for Talar CutBACKGROUND OF THE INVENTION

[0001] Field of the Invention

[0002] The invention relates to a balancer system to assist in making proper talar cuts for total ankle replacement surgery.

[0003] Description of the Related Art

[0004] Present tools for performing talar cuts as part of total ankle replacement surgery do not allow for the surgeon to check the balance before the talar cut is made, resulting in a potentially unstable cut. It would be beneficial to provide a balancer system that allows the surgeon to check the balance before the cut is made to make sure that the cut is properly aligned.SUMMARY OF THE INVENTION

[0005] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0006] In one embodiment, the present invention is a balancer assembly for a talar cut. The assembly includes a spreader having a distal end, a balancer releasably attachable to the distal end of the spreader, and a rotational aligner releasably attachable to the spreader. An alignment block is attached to the rotational aligner; and a tibial aligner is attached to the alignment block.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate the presently preferred embodiments of the invention, and, together with the general description given above and the detailed description given below, serve to explain the features of the invention. In thedrawings:

[0008] FIG. 1 is a perspective view of a ligamentaxis joint spreader with a balancer assembly;

[0009] FIG. 2 is a perspective view of the spreader of FIG. 1 with the balancer assembly of FIG. 1 with an attachment block attached thereto;

[0010] FIG. 3 is a top plan view of a Talar U-limb aligner of FIG. 2;

[0011] FIG. 4 is a rear elevational view of the Talar U-limb aligner;

[0012] FIG. 5 is a side elevational view of a Tibial U-limb aligner;

[0013] FIG. 6 is a perspective view of the Tibial U-limb aligner of FIG. 5;

[0014] FIG. 7 is a top plan view of the talar U-limb aligner of FIG. 2 attached to a spreader;

[0015] FIG. 8 is a rear perspective view of the U-limb aligner of FIG. 7;

[0016] FIG. 9 is a side perspective view of the U-limb aligner of FIG. 5 attached to a cutting block;

[0017] FIG. 10 is a side elevational view of the U-limb aligner of FIG. 7;

[0018] FIG. 11 is a bottom perspective view of the U-limb aligner of FIG. 7, showing rotational axes;

[0019] FIG. 12 is a top plan view of the cutting block of FIG. 9;

[0020] FIG. 13 is a perspective view of the cutting block of FIG. 12;

[0021] FIG. 14 is an axial / coronal alignment guide;

[0022] FIG. 15 is a perspective view of the axial / coronal alignment guide of FIG.14 inserted into the alignment block of FIG. 12;

[0023] FIG. 16 is an end elevational view of the cutting block of FIG. 12;

[0024] FIG. 17 is a side elevational view of an assembly of the U-limb aligners of FIGS. 3 and 7 with the cutting block of FIG. 16;

[0025] FIG. 18 is a perspective view of the assembly of FIG. 17;

[0026] FIG. 19 is side elevational view of the assembly of FIG. 17;

[0027] FIG. 20 is a side elevational view of the spreader of FIG. 1, with the U- limb aligners in a spread position;

[0028] FIG. 21 is a side elevational view of the spreader of FIG. 20, with the U- limb aligners in a retracted position;

[0029] FIG. 22 is a perspective view of the spreader of FIG. 1 with the balancerassembly inserted into an ankle joint;

[0030] FIG. 23 is a side elevational view of the spreader and balancer of FIG. 22;

[0031] FIG. 24 is a perspective view of the balancer of FIG. 22 in a spread position, with the spreader removed;

[0032] FIG. 25 a side elevational view of the balancer of FIG. 24;

[0033] FIG. 26 is a front elevational view of the cutting block of FIG. 16, the aligners of FIGS. 3 and 7, and the alignment rod of FIG. 14 with the spreader of FIG. 1 inserted into an ankle joint;

[0034] FIG. 27 is a front elevational view of the cutting block of FIG. 16, the aligners of FIGS. 3 and 7, and the alignment rod of FIG. 14 with the spreader removed;

[0035] FIG. 28 is a front elevational view of the cutting block of FIG. 16 and the aligners of FIGS. 3 and 7, with the alignment rod and the spreader removed;

[0036] FIG. 29 is a side elevational view of the cutting block of FIG. 16 and the aligners of FIGS. 3 and 7.DETAILED DESCRIPTION

[0037] In the drawings, like numerals indicate like elements throughout. Certain terminology is used herein for convenience only and is not to be taken as a limitation on the present invention. The terminology includes the words specifically mentioned, derivatives thereof and words of similar import. The embodiments illustrated below are not intended to be exhaustive or to limit the invention to the precise form disclosed. These embodiments are chosen and described to best explain the principle of the invention and its application and practical use and to enable others skilled in the art to best utilize the invention.

[0038] Reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments necessarily mutually exclusive of other embodiments. The same applies to the term "implementation."

[0039] As used in this application, the word "exemplary" is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the word exemplary is intended to present concepts in a concrete fashion.

[0040] The word "about" is used herein to include a value of + / - 10 percent of the numerical value modified by the word "about" and the word "generally" is used herein to mean "without regard to particulars or exceptions."

[0041] Additionally, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless specified otherwise, or clear from context, "X employs A or B" is intended to mean any of the natural inclusive permutations. That is, if X employs A; X employs B; or X employs both A and B, then "X employs A or B" is satisfied under any of the foregoing instances. In addition, the articles "a" and "an" as used in this application and the appended claims should generally be construed to mean "one or more" unless specified otherwise or clear from context to be directed to a singular form.

[0042] Unless explicitly stated otherwise, each numerical value and range should be interpreted as being approximate as if the word "about" or "approximately" preceded the value of the value or range.

[0043] The use of figure numbers and / or figure reference labels in the claims is intended to identify one or more possible embodiments of the claimed subject matter in order to facilitate the interpretation of the claims. Such use is not to be construed as necessarily limiting the scope of those claims to the embodiments shown in the corresponding figures.

[0044] It should be understood that the steps of the exemplary methods set forth herein are not necessarily required to be performed in the order described, and the order of the steps of such methods should be understood to be merely exemplary. Likewise, additional steps may be included in such methods, and certain steps may be omitted or combined, in methods consistent with various embodiments of the present invention.

[0045] Although the elements in the following method claims, if any, are recited in a particular sequence with corresponding labeling, unless the claim recitationsotherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence.

[0046] Referring to the Figures, a balancer assembly 100 for spreading an ankle joint for the insertion of an implant is shown. An exemplary spreader 110 is used after the balancer assembly is inverted into an ankle joint between a talus and a tibia to spread the ankle joint for the insertion of the implant (not shown) in a total ankle replacement (TAR) surgery.

[0047] Exemplary spreader 110, shown in FIGS. 1 and 2 (without a screw to bias arms apart), can be used to spread the ankle joint, although those skilled in the art will recognize that other spreaders can be used. Spreader 110 has a proximal handle 112 with arms 114, 116 that are biased apart by a biasing member 118, such as, for example, a torsion spring. Spreader 110 is interchangeable between a left or right ankle joint.

[0048] Spreader 110 has a distal end 119 to which a balancer assembly 120 according to the present invention can be attached. Spreader 110 can include 2-4 strain gauges 138, which can digitally indicate the balancing grade between the medial and lateral side of the joint, to better enable the clinician to select the proper replacement joint alignment.

[0049] An exemplary bottom rotational U-limb aligner 130 is shown in FIG. 3. Aligner 130 has a generally "U-prong" shaped distal end 132 with a medial arm 134 and a lateral arm 136, parallel to medial arm 134. Strain gauges 137, 138 are attached to arms 134, 136, respectively. Strain gauges 137, 138 measure the force applied to arms 134, 136, respectively, to allow the clinician to determine if the proposed talar cut will be properly balanced on the tibial cut. A bottom face of each of arms 134, 136 can be contoured in a convex shape to better engage the talus 50. In an exemplary embodiment, two to four strain gauges 137,138 can be attached onto the contoured bottom faces. In an exemplary embodiment, the contoured surface can range from 20-50mm radius.

[0050] Distal end 132 extends from an arm 139 that is rotatable about a longitudinal axis "A". Arm 139 is rotationally attached to and longitudinally adjustably insertable into alignment block 140, shown in FIGS. 3, 4, 7, 8, 10, and11. Alignment block 140 is generally cuboid in shape with a block 141 having threaded openings 142, 144 evenly spaced on either side of a central slot 146. Block 141 is attached to arm 139 through alignment block 140 and is rotatable about the alignment block 140 along the same axis of rotation "A" as arm 139. Threaded openings 142, 144 are used to releasably attach aligner 130 to a cutting block 170 (shown in FIGS. 12 and 13).

[0051] Referring now to FIGS. 5, 6, and 9, a tibial U-limb aligner 150 is shown. Similar to aligner 130, tibial aligner 150 has a generally "U-prong" shaped distal end 152 with a medial arm 154 and a lateral arm 156, parallel to medial arm 154, all extending in a first plane. Distal end 152 extends from a fixed arm 160. An extender portion 162 extends upwardly and away from the proximal end of arm 160 ain a second plane, different from the first plane. Extender portion 162 is connected to alignment block 140.

[0052] FIGS. 12, 13, and 16 show cutting block 170. Cutting block 170 includes an alignment rod 172 that extends from a vertical portion 174. Vertical portion 174 includes a pair of through openings 176, 178 that align with alignment block 150 such that connectors, such as screws (not shown), can be inserted into through openings 176, 178 and into threaded openings 142, 144, respectively, in alignment block to releasably connect cutting block 170 to alignment block 150 to ensure that the cutting block 170 is parallel to "U-prong" distal end 152 of aligner 150.

[0053] Aligner 150 can be provided in different sizes to align with the tibial cut.

[0054] Cutting block 170 also includes a base portion 180 that extends from vertical portion 174 below alignment rod 172. Base portion 180 includes an elongate slot 182 extending therethrough that can accept a cutting tool to cut the top portion of talus 50. Additionally, vertical portion 174 includes a "T-slot" 184 on the anterior face that accepts an alignment tool 190, shown in FIGS. 14 and 15.

[0055] Cutting block 170 can be provided in varying sizes to better match the anatomy of the patient.

[0056] T-slot 184 accepts a complementary T-shaped projection 192 on tool 190. Tool 190 also includes a horizontal rod 194 that extends anteriorly from projection 192 and a vertical rod 196 that extends orthogonally relative to rod 194. Rods 184, 196 are used to manipulate cutting block 170 and to align cutting block 170 withthe vertical axis of tibia 52.

[0057] FIGS. 17-19 show different views of assembly 100, with both U-Aligners 130, 150 attached to cutting block 170.

[0058] FIGS. 20 and 21 show assembly 100 attached to spreader 110. FIG. 21 also includes alignment tool 190.

[0059] A method of enlarging the space between a talus 50 and a tibia 52 is shown in FIGS. 22-29. Referring specifically to FIGS. 23 and 23, aligners 130, 150 are attached to spreader 110 and inserted between a talus 50 and a tibia 52. A slot 54 has already been cut in the bottom of tibia 52, according to known methods. As shown in FGIS. 24 and 25, spreader 110 (removed for clarity) has been used to separate aligners 130, 150 from each other, distracting the ankle joint. Aligner 130 can pivot along the axis "A" to ensure contact with tibia 52 on either side of slot 54. Strain gages 137, 138 are observed to ensure even, or near even, force is being applied by tibia 52 on both sides of slot 54. If the force is not even, ensure tibial cut 52 is correct or perform soft tissue balancing. If the force is even, no additional balancing is required and the talar cut is performed.

[0060] As shown in FIGS. 26 and 27, cutting block 170 is attached to alignment block 140 and the top of talus 50 is cut to form a platform for the new implant. After talus 50 is cut, assembly 10 is removed, the cut is chamfered, and peg holes are drilled in talus 50 to accept the implant. The implant is then inserted into the gap between talus 50 and tibia 52 according to known methods.

[0061] While the description and pictures referenced herein are directed to preparing a tibia and talus for a total ankle replacement, those skilled in the art will recognize that a similar procedure can be performed for a femoral or proximal tibia cut to prepare the bones for a total knee replacement procedure.

[0062] It will be further understood that various changes in the details, materials, and arrangements of the parts which have been described and illustrated in order to explain the nature of this invention may be made by those skilled in the art without departing from the scope of the invention as expressed in the following claims.

Claims

CLAIMSI claim :

1. A balancer assembly for a talar cut comprising: a spreader having a distal end; a balancer releasably attachable to the distal end of the spreader; a rotational aligner releasably attachable to the spreader; an alignment block attached to the rotational aligner; and a tibial aligner attached to the alignment block.

2. The balancer assembly according to claim 1, wherein the spreader is configured to spread the rotational alihgner relative to the tibial aligner.

3. The balancer assembly according to claim 1, wherein the spreder comprises a proximal handle having arms, the arms biased apart by a biasing member.

4. The balancer assembly according to claim 3, wherein the biasing member comprises a torsion spring.

5. The balancer assembly according to claim 1, wherein the rotational aligner comprises a U-shaped body having a pair of spaced apart arms.

6. The balancer assembly according to claim 5, further comprising a strain gauge attached to each of the pair of spaced apart arms.

7. The balancer assembly according to claim 5, wherein each of the pair of spaced apart arms has a convex surface.

8. The balancer assembly according to claim 5, wherein the rotational aligner comprises an arm extending away from the pair of spaced apart arms, the arm being rotationally attached to the alignment block.

9. The balancer assembly according to claim 8 wherein the arm is longitudinally adjustable inside the alignment block.

10. The balancer assembly according to claim 1, wherein the tibial algner comprises a U-shaped body having a pair of spaced apart alinger arms.11.The balancer assembly according to claim 10, wherein the aligner arms extend in a first plane.

12. The balancer assembly according to claim 11, further comprising an extrender extending away from the aligner arms and extending in a second plane, different from the first plane.13.The balancer assembly according to claim 1, further comprising a cutting block releasably attachable to the aligner.

14. The balancer assembly according to claim 13A, wherein the cutting block comprises an elongate slot configured to accept a cutting tool inserted therein.

15. The balancer assembly according to claim 13, wherein the cutting block comprises a T-shaped slot formed therein.

16. The balancer assembly according to claim 15, further comprising an alignment tool removably insertable into the cutting block.

17. The balancer assembly according to claim 16, wherein the alignment tool comprises a T-shaped projection configured to be inserted into the T-shaped slot in the cutting block.

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