Effect of Electrical Stimulation to the Vastus Medialis Muscle in a Patient with Chronically Dislocating Patellae

Abstract

Lateral subluxation and dislocation of the patella have been attributed to a number of different anatomical and functional abnormalities. These abnormalities include an increase in the “Q” angle above 15 degrees, a high-riding patella (patella alta), an external tibial torsion, a lateral insertion of the patellar tendon, a tilted patella, a low lateral femoral condyle, and a hypoplasia of the vastus medialis muscle.^1–3 Regardless of the abnormality, however, conservative treatment is generally directed toward strengthening the quadriceps mechanism by resistive exercise.^1–5 Although the quadriceps mechanisms of individuals with patellar problems have been found to generate less knee extension torque than healthy individuals,⁶ quadriceps femoris muscle strengthening may be accompanied by complications. Even when performed with EMG feedback, resistive exercise may lead to further augmentation of the lateral vector of the quadriceps femoris muscle force.⁷ Such an augmentation could conceivably increase the tendency of the patella to sublux or dislocate laterally.