Abstract
Many factors have been reported as possible causes of patella dislocations. External rotation of the quadriceps muscle is one of these. The route of the quadriceps muscle was examined in 9 patients of patella dislocation and 2 normal volunteers in the abnormal position by means of MRI. All of them were female. We evaluated the rectus femolis external rotation angle (∠CR) and the vastus tilting angle (∠CV) in each case.
In 4 cases with patella dislocation, the results suggested that the causes were either external rotation of the quadriceps muscle or lateral deviation of the muscle force vector. It was shown that the ∠ CR is a useful index of the external rotation of the quadriceps muscle, and that the value of the ∠ CV depends on the condition of the distal part of the quadriceps muscle.
