ECVS resident in small animal surgery University of Zurich zurich, Zurich, Switzerland
Few studies reported outcomes of three-dimensional (3D) measurement of femoral angles in canine specimens, while no data are available in clinical cases. The purpose of this study is reporting outcomes after using 3D measurement of femoral angles in dogs with patellar luxation (PL). We hypothesize that 3D measurements can be reliably used as preoperative reference values. A computed tomography (CT) and segmentation were performed. 3D femur models were exported as stereolithographic files and imported in a computed-aided-design (CAD) software. 3D automated measurements were performed, recording the anatomic laterodistal femoral (aLDFA) and femoral torsion (FTA) angle. Surgical records and complications were reviewed, with pre- and postoperative lameness and patellar position. Clinical outcomes were defined as full functional, acceptable, or unacceptable functional. Forty-one dogs and 47 limbs were included. Mean 3D aLDFA and FTA measurements were 99° and 16° in dogs with medial-PL, and 85° and 31° in dogs with lateral-PL. Corrective osteotomies were performed in 30/47 cases. Mean radiographic follow-up was 4.7 months. At final follow-up PL was successfully treated in 95% of cases. Patella reluxated in 10% of the cases with a complication rate of 35%. Sixty-six and 26% of dogs had a fully functional and functional clinical outcome respectively. The initial learning curve for segmentation is the main limitations for using such methodology. 3D femoral measurements can be reliably used as preoperative reference values to guide the surgical treatment of PL in dogs. The automated and 3D nature of this approach allows for decreasing positioning and manual-related measurement errors.
