The purpose of this thesis was to examine the effects of imbalance between the forces exerted by vastus medialis (VM) and vastus lateralis on patellofemoral peak contact pressures, areas, shapes, and patellar tracking before and after the removal of VM. New Zealand White rabbits were used and patellofemoral contact mechanics were evaluated at 30°, 60° and 90° and patellar tracking was recorded from 30°-90° before and after VM transection. Following removal of VM, there were no changes in patellofemoral contact mechanics and patellar tracking. We conclude that VM weakness does not cause changes in rabbit patellofemoral contact mechanics. Since muscular alignment and knee joint geometry are similar in human and rabbits, we question the idea of VM weakness as a cause for patellar mal-tracking and patellofemoral joint pain.