The effect of tibial plateau leveling osteotomy on patellofemoral kinematics in dogs: An in vivo study.

Abstract

To quantitatively evaluate patellofemoral (PF) kinematics during walking in dogs with cranial cruciate ligament (CrCL) deficiency treated by tibial plateau leveling osteotomy (TPLO). Longitudinal observational study. Dogs with unilateral CrCL deficiency treated by TPLO (n = 10). Horizontal beam fluoroscopic images of the stifles during treadmill walking were acquired 6 months after TPLO. Computed tomography was performed, and digitized bone models of both femurs and patellae were created. These digital models were superimposed over the fluoroscopic images with shape-matching software, and sagittal plane PF kinematics for TPLO-treated and normal contralateral stifles were calculated. Patellofemoral kinematics were described according to phase of gait cycle as well as relative to femorotibial flexion angle. In TPLO-treated stifles, there was an approximately 1-mm increase in cranial displacement of the patella (P < .05) compared with the normal stifle at equivalent femorotibial flexion angles between 120° and 140° and predominately during the stance phase. Proximal-distal translation and patellar flexion angle were mostly unaffected by TPLO when they were assessed according to either equivalent phase of gait cycle or femorotibial flexion angles. In vivo PF kinematics in TPLO-treated stifles were subtly different from normal, characterized by slight cranial shifting of the patella relative to the trochlear groove. The clinical significance of these results remains unknown. These results may provide further understanding into extensor mechanism abnormalities associated with TPLO.