Custom‐built constrained uniaxial and rotating hinge total knee replacement in cats: Clinical application, design principles, surgical technique, and clinical outcome

Abstract

Objective: To describe the design principles and evolution, surgical technique, and outcome for custom constrained (uniaxial and rotating hinge) total knee replacement (TKR) in cats.Study design: Retrospective case series. Animals: Nine cats with traumatic stifle luxation (n = 8) or severe distal femoral deformity (n = 1) were considered suitable candidates. Methods: Cats that met eligibility criteria and received a custom TKR between 2009 and 2018 by a single surgeon were included in this case series. Three generations of implant were used. Implant positioning was assessed by postoperative orthogonal radiography. Functional outcome was determined by clinical assessment, owner interview, and a feline musculoskeletal pain index questionnaire.Results: Median clinical follow-up time was 12 months (range, 4-41); follow-up time was increased to 29 months (range, 22-47) when results of functional questionnaires with owner were included. Median radiographic follow-up was 12 months (range, 4-25). One cat had a catastrophic outcome. Three cats had good outcomes, and five cats had excellent outcomes. Conclusion: Most cats treated with custom-built TKR achieved good to excellent outcomes. Clinical significance: Custom TKR is a viable option for the treatment of severe pathologies of the feline stifle. Additional research is required to fully evaluate implant suitability.

Active Materials for 3D Printing in Small Animals: Current Modalities and Future Directions for Orthopedic Applications

“…The implant in this case was a custom-made constrained uniaxial and rotating hinge TKR. However, additional cases and research are required to evaluate the feasibility of TKR in cats [54].…”

“…The accuracy of corrective osteotomy surgery appears to be effectively increased by utilizing 3D-printing replica for accurate planning of the procedure [8,37]. This may also contribute to successful surgical outcomes [35,54]. Overall, based on the surgeons' professional knowledge, RP was deemed useful to the receiver by reducing the surgical time, morbidity, and mortality, as well as lowering overall costs [16].…”

3D‐printed, patient‐specific cutting guides improve femoral and tibial cut alignment in canine total knee replacement

“…24 Careful preparation and attention to detail is crucial to avoid complications and errors that may lead to ligament damage or instability, loosening of the implant and pain. 4,14,15 In our experience, the tibial and femoral ostectomies are the most F I G U R E 9 Femoral component alignment in canine total knee replacement (TKR) performed with generic or patient-specific guides (PSGs). (A) In the frontal plane, varusvalgus alignment of the femoral component was similar in the two groups.…”

“…We have previously reported that surgical navigation improves tibial component alignment in canine TKR, 23 but without a commercial veterinary navigation system on the market, these benefits cannot be realized at present. However, most veterinary referral centers have easy access to CT scanning, and the clinical success of PSGs in other areas of veterinary orthopedics, including spine surgery and long bone deformity correction, [6][7][8][9][10][11][12][13][14] provides a strong rationale for exploring their utility in canine TKR. In this study, all the knees operated with the assistance of PSGs fell within 3 degrees of neutral in the frontal plane.…”

“…In veterinary medicine, the use of PSGs has garnered significant attention in the last few years, with potential application in the correction of antebrachial growth deformities, [7][8][9] the drilling of transcondylar screws in humeral fractures and humeral intracondylar fissures, 10 atlanto-axial stabilization, 11,12 pedicle screw placement, 13 and femoral osteotomy. 14 There have been isolated reports on the use of PSGs with custom canine and feline TKR implants, 15,16 but their utility and accuracy have not been evaluated in a systematic manner to date. We hypothesized that PSGs would improve the surgeon's accuracy in delivering the planned implant alignment in TKR surgery.…”