Prostheses and methods for acetabular rim restoration in quadruped mammals

Abstract

Prostheses and methods for dorsal acetabular rim restoration at the acetabulum of the pelvis of a quadruped mammal, for example for treatment of canine hip dysplasia, are disclosed. The prosthesis includes a unitary implantable structure defining a pelvic portion and a concave portion with an arcuate rim extending from and at parts elevated relative to the pelvic portion. The pelvic portion is adapted for securement at an implant site utilizing suitable means.

Claims

1. A prosthesis for dorsal acetabular rim restoration at the acetabulum of the pelvis of a quadruped mammal comprising a pelvic portion with a surface adapted for securement at the pelvis adjacent to the acetabulum and a concave portion including an arcuate rim extending from and elevated at parts relative to said pelvic portion.

2. The prosthesis of claim 1 made of at least one of plastic, metal, ceramic, biological extracellular matrix material, hydroxyapatite, and cellular material.

3. The prosthesis of claim 1 made of ultra-high-molecular-weight polyethylene.

4. The prosthesis of claim 3 wherein the ultra-high-molecular-weight polyethylene is established on a titanium mesh or foam framework.

5. The prosthesis of claim 1 made of semi-rigid material having a selected extent of flexibility to conform to pelvic implantation securement site variations.

6. The prosthesis of claim 1 wherein said pelvic portion includes openings, the prosthesis further comprising bone screws adapted for receipt through said openings.

7. The prosthesis of claim 1 wherein said pelvic portion includes micro-porous structure at least at said surface thereof adapted to allow boney ingrowth.

8. A prosthesis for treatment of canine hip dysplasia comprising: a first portion including a pelvic implant site securement structure; a second portion defining a concavity with an arcuate rim adaptation and extending from said first portion; and securement means for securing the prosthesis at said securement structure of said first portion at an implant site.

9. The prosthesis of claim 8 manufactured in various sizes to conform to a variety of differences in diagnosed cases of canine hip dysplasia,

10. The prosthesis of claim 8 wherein said securement means includes at least one of bone screws and bone cement.

11. The prosthesis of claim 8 wherein said first portion and said second portion are a unitary structure.

12. The prosthesis of claim 8 wherein said first portion exhibits a selected extent of flexibility and wherein said securement structure and said securement means are adapted for immobility of the prosthesis.

13. The prosthesis of claim 8 wherein said arcuate rim adaptation is a dorsal acetabular rim adaptation, said concavity and said rim adaptation configured for femoral head engagement.

14. A method for deficient dorsal acetabular rim restoration in a bony pelvis of a quadruped mammal comprising the steps of: measuring the deficient dorsal acetabular rim to provide a profile; surgically exposing the deficient dorsal acetabular rim; preparing the deficient dorsal acetabular rim to establish an implant site; selecting a suitably configured artificial acetabular rim restoration prosthesis from the profile; and securing the suitably configured artificial acetabular rim restoration prosthesis at the implant site.

15. The method of claim 14 wherein the step of measuring the deficient dorsal acetabular rim is performed non-invasively.

16. The method of claim 14 wherein the step of securing an artificial acetabular rim restoration prosthesis includes securing a pelvic portion of the prosthesis at the implant site, the prosthesis being semi-rigid with the at least the pelvic portion exhibiting a selected extent of flexibility.

17. The method of claim 14 wherein the step of securing an artificial acetabular rim restoration prosthesis includes forming screw receiving holes in the bony pelvis of the mammal at the implant site corresponding to securement openings in the prosthesis.

18. The method of claim 14 wherein the step of selecting a suitably configured artificial acetabular rim restoration prosthesis includes configuring the prosthesis with a pelvic portion having micro-porous structure adapted to allow boney ingrowth.

19. The method of claim 14 wherein the step of surgically exposing the deficient dorsal acetabular rim includes one of making a surgical incision using a posterior, muscle splitting technique or exposing the deficient rim endoscopically.

20. The method of claim 14 wherein the step of selecting a suitably configured artificial acetabular rim restoration prosthesis includes configuring the prosthesis using at least one of plastic, metal, ceramic, biological extracellular matrix material, hydroxyapatite, and cellular material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings illustrate a complete embodiment of the invention according to the best mode so far devised for the practical application of the principles thereof, and in which:

[0028] FIG. 1 is a perspective view of a portion of a healthy canine pelvic bone;

[0029] FIG. 2 is a perspective view of a pelvic bone portion as shown in FIG. 1 but exhibiting deterioration of the acetabular rim typical of hip dysplasia;

[0030] FIG. 3 is a perspective view of a canine hip joint with a deteriorated acetabulum as shown in FIG. 2;

[0031] FIG. 4 is a bottom perspective view of the prosthesis of this invention;

[0032] FIG. 5 is a side perspective view of the prosthesis of this invention;

[0033] FIG. 6 is another side perspective view of the prosthesis of this invention;

[0034] FIG. 7 is a top perspective view of the prosthesis of this invention;

[0035] FIG. 8 is a perspective view of the prosthesis of this invention being implanted at the acetabular rim of the pelvic bone portion shown in FIG. 2;

[0036] FIG. 9A is a perspective view of portions of the canine hip joint of FIG. 3;

[0037] FIG. 9B is a sectional view taken through section lines B-B of FIG. 9A;

[0038] FIGS. 9C and 9D are perspective views of the left and right sides, respectively, of a pelvic bone/hip joint each having an implanted prosthesis of this invention;

[0039] FIG. 9E is a sectional view taken through section lines E-E of FIG. 9D; and

[0040] FIGS. 10 and 11 are perspective view illustrations of implanting of the prosthesis of this invention.

DESCRIPTION OF THE INVENTION

[0041] FIGS. 4 through 7 show a currently preferred embodiment of prosthesis 17 of this invention. Initially conceived of to treat symptoms of hip dysplasia in canines, the prostheses and methods described herein can be adapted for use in any quadruped mammal that develops deficiency of the dorsal acetabular rim similar to the deficiency produced by canine hip dysplasia (for example, by inheritance, disease or trauma). Thus, while the description herein utilizes canine examples and skeletal/physiological terminology, it should be understood to apply to any such deficiency in other quadruped mammals.

[0042] Prosthesis 17 includes a unitary implantable structure adapted for dorsal acetabular rim restoration at the acetabulum of the pelvis of the animal presented for treatment. Pelvic portion 19 has a bottom surface 21 that is adapted (both surface contour and size) for securement at pelvic bone 23 adjacent (dorsal) to the acetabulum 25 and dorsal rim 27. Concave portion 29 defines concavity 31 and arcuate rim 33 (a dorsal acetabular rim adaptation) and is adapted and configured for femoral head 34 engagement as shown in FIGS. 9C, 9D and 9E. Portion 29 (and thus concavity 31 and rim 33) extends from pelvic portion 19 and is elevated at parts relative to portion 19 (and thus pelvic bone 23 once implanted). As used herein the term elevated is not to be understood to mean at a higher altitude in any geographically absolute sense, but only to mean shifted positionally relative to surface 21 so as to be offset from pelvic bone 23 once implanted.

[0043] In this embodiment of prosthesis 17, pelvic portion 19 includes openings 35 for bone screws for securement of the prosthesis at the implant site. This securement structure feature could however be replaced (for example, by structure or surface preparation at surface 21 adapted to achieve long lasting securement using known bone cements). Suitable means for securement of prosthesis 17 at the implant site are provided (for example, bone screws 37 as shown in FIGS. 8 and 9) adapted to assure long term immobility of the prosthesis relative to pelvic bone 23.

[0044] The prostheses 17 can be made of any material not likely to be rejected including plastics, metals, ceramics, biological materials (such as collagen or other extracellular matrix materials), hydroxyapatite, cellular materials (such as stem cells, chondrocyte cells or the like) or combinations thereof. At present, the preferred material is ultra-high-molecular-weight polyethylene. This material may be used alone in formation of prostheses 17, or could be established on a titanium mesh or foam framework. Whatever material is used, it should be semi-rigid while exhibiting a selected extent of flexibility (particularly at pelvic portion 19) to conform to pelvic implantation securement site variations which may be encountered. That is, the material used should provide the hardness needed to maintain contact with femoral head 34 while yet resisting excessive wear to either the prosthesis or the femoral head. The material selected may also usefully be selected to provide micro-porous structure, at least at surface 21 thereof, adapted to allow bony ingrowth from a properly surgically prepared dorsal acetabular rim 27 to provide a more durable mending and long term strength between prosthesis 17 and bone 23 at the surgical implant site. A variety of sizes can be provided to conform to differences in diagnosed cases that may be encountered. Prostheses 17 can be configured for either left or right side acetabular rim/hip joint repair (as shown in FIGS. 9C and 9D, respectively).

[0045] Turning now to FIGS. 9 through 11, a description of methods adapted to surgical implant of the prostheses of this invention will proceed. The deficient dorsal acetabular rim 27 (see FIGS. 2, 3, 8 and 9A) at the patient's bony pelvis is appropriately measured providing an implant site profile. These measurements and profile help in selection of implant size and, in some cases, surface 21 site orientation. Non-invasive measurement, for example utilizing well known radiographic techniques providing extended and DAR views, is preferred though in-situ measurement during the procedure may be employed instead or in addition. CT imaging, MRI, or ultrasound could instead be used. The deficient dorsal acetabular rim may be surgically exposed and the implant site properly prepared once a suitably configured artificial acetabular rim restoration prosthesis has been selected fitting the profile. The prosthesis is located at the bony pelvis implant site through a surgical incision using, for example, posterior, muscle splitting techniques. Alternatively, prosthesis location and securement techniques could be developed utilizing endoscopic methods and instrumentation. Once located, the prosthesis is secured at the pelvic bone as heretofore described, for example by forming screw receiving holes in the bony pelvis at the implant site corresponding to the securement openings in and desired orientation of the prosthesis. Once secured, the site is cleaned and prepared for closing, and the various required incisions are then closed.

[0046] As may be appreciated from the foregoing, this invention provides prostheses and methods for dorsal acetabular rim restoration whereby stable and long lasting rim/joint repair is achieved with less discomfort and risk for the animal. This positively fixed restoration adds depth to the acetabulum thereby providing near normal support for the hip joint.