Objectives This study aimed to develop a standardized ostectomy guide for the 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.
Methods CT scans of 18 cats with normal femoral morphology were obtained to determine ideal ostectomy planes and generate 3D-printed femurs. A standardized ostectomy guide was designed, printed and used to perform the ostectomies on printed bones as well as three cadavers via vFHO. Post-operative CT scans were obtained. Covariates including age, sex, castration 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.
Results The ideal and actual ostectomy angles in the 3D-printed femur models were statistically equivalent (p < 0.005), while the percentage of femur removed was not (p = 0.080), until two outlier specimens (smallest/youngest) were excluded, after which both measurements became statistically equivalent (p = 0.001). No covariates significantly influenced outcomes. Visual assessment from a blinded surgeon found 75% of ostectomies 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 previously described ventral approach.
Conclusions and relevance This study demonstrated that while 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.
