OBJECTIVE: To quantitatively evaluate patellofemoral (PF) kinematics during walking in dogs with cranial cruciate ligament (CrCL) deficiency treated by tibial plateau leveling osteotomy (TPLO).
STUDY DESIGN: Longitudinal observational study.
ANIMALS: Dogs with unilateral CrCL deficiency treated by TPLO (n = 10).
METHODS: 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.
RESULTS: 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.
CONCLUSION: 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.
CLINICAL SIGNIFICANCE: The clinical significance of these results remains unknown. These results may provide further understanding into extensor mechanism abnormalities associated with TPLO.