Femoral head and neck ostectomy via ventral approach in cats using a standardized three-dimensional-printed ostectomy guide

ObjectivesThis study aimed to develop a standardized ostectomy guide for ventral femoral head and neck ostectomy (vFHO) in cats. We aimed to assess the guide's accuracy for maximizing removal of a clinically acceptable amount of bone without sacrificing soft tissue attachments.MethodsCT scans of 18 cats with normal femoral morphology were obtained to determine ideal ostectomy planes and generate three-dimensional (3D)-printed femurs. A standardized ostectomy guide was designed, printed and used to perform the ostectomies on printed bones as well as on three cadavers via vFHO. Postoperative CT scans were obtained. Covariates including age, sex, neuter status, body weight, side and neck inclination, and version angles were recorded. Ostectomies were assessed by comparing actual vs ideal ostectomy angles and percentage of femoral head and neck removed using CT scan data, and by blinded evaluation of printed bones with vFHO. Mixed-effects models were used for statistical analysis.ResultsThe ideal and actual ostectomy angles in the 3D-printed femur models were statistically equivalent (<i>P</i> <0.005), whereas the percentage of femur removed was not (<i>P</i> = 0.080) until two outlier specimens (smallest/youngest) were excluded, after which both measurements became statistically equivalent (<i>P</i> = 0.001). No covariates significantly influenced outcomes. Visual assessment by a blinded surgeon found 75% of ostectomies to be acceptable; unacceptable ostectomies had either over-removal of the greater trochanter or incomplete neck resection. Cadaveric testing confirmed the guide's usability, with practical application and adequate exposure via a previously described ventral approach.Conclusions and relevanceThis study demonstrated that although a standardized vFHO ostectomy guide in cats was practical to use and produced ostectomies statistically equivalent to ideal cuts, occasional over- or under-resection and the risk of damaging the greater trochanter preclude clinical application at this stage, highlighting the need for further design optimization.