The focus of this thesis is the application of an MRI-based method to assess the effect of high tibial osteotomy (HTO) on patellar tracking and tibial kinematics. Patellar tracking patterns were assessed in 4 subjects who underwent closing wedge HTO (CWO) and 3 subjects who underwent opening wedge HTO (OWO). The resultant tracking patterns were compared using a two-way repeated measures ANOVA.

Specifically, our research was focused on the three-dimensional joint motion of the patellofemoral joint during loaded knee flexion. The process involves the registration of bone models derived from the segmentation of high-resolution MRI scans to bone outlines which are derived from fast, low-resolution MRI scans taken of the knee joint in loaded flexion. Using the Joint Coordinate System, full three-dimensional description of the relative position and orientation of the knee bones for one position of loaded flexion can be developed. This method has been shown to be highly accurate and repeatable.

Statistical analysis of the pre- and post-operative patellar tracking patterns following CWO showed that four of six patellar kinematic parameters were significantly altered. CWO significantly decreased mean patellar flexion over the flexion range from 12.12 (6.12)° pre-operatively to 7.06 (5.32)° post-operatively (p < 0.003). CWO significantly decreased mean internal patellar spin over the flexion range from 1.77 (5.36)° pre-operatively to 0.52 (5.40)° post-operatively (p < 0.001). CWO significantly increased mean medial patellar tilt over the flexion range from 14.58 (5.63)° preoperatively to 16.17 (5.48)° post-operatively (p < 0.001). CWO significantly increased mean proximal patellar translation over the flexion range from 14.60 (4.47) mm preoperatively to 18.79 (4.34) mm post-operatively (p < 0.008).

Statistical analysis of the pre- and post-operative patellar tracking patterns following OWO showed significant differences in two of six patellofemoral kinematic parameters. OWO significantly decreased mean internal patellar spin value over the flexion range from 1.968 (3.002)° pre-operatively to -0.377 (2.348)° post-operatively (p < 0.001). OWO significantly increased mean lateral patellar translation value over the flexion range from -5.29 (6.64) mm pre-operatively to -4.14 (6.68) mm post-operatively (p < 0.001).

The changes in the patellofemoral and tibiofemoral joint motion following CWO were expected, while the changes due to OWO were surprising. This was attributed to the small sample size for the OWO study.

Both CWO and OWO affect kinematic variables (proximal patellar translation, medial patellar tilt and lateral patellar translation) associated with patellar instability, recurrent patellar subluxation and increased pressures on lateral facets of the patella