Patellar location changes following EMG biofeedback or progressive resistive exercises.

Changes in the patellofemoral congruence (PFC) angle, the patellar rotation (PR) angle, and the sulcus angle following EMG biofeedback training that emphasized vastus medialis obliquus strengthening, the Daily Adjustable Progressive Resistive Exercise (DAPRE) technique, or no exercise were studied. Subjects were 30 normal, college females. The EMG biofeedback group and the DAPRE group followed established protocols for a 3-wk training period. The control group refrained from exercise. Patellar angles were determined with x-rays both pre- and posttest with the quadriceps relaxed and contracted. Reliability of the x-rays was determined with a correlation matrix of pre- and posttest sulcus angle measurements (P less than 0.001). EMG biofeedback training resulted in significant changes in the PFC angle with the quadriceps contracted (P less than 0.05). DAPRE resulted in significant changes in the PR angle with the quadriceps contracted (P less than 0.05). The results of this study suggest that quadriceps group strength changes are not enough to fully rehabilitate patellar tracking dysfunctions. The use of EMG biofeedback training to selectively strengthen the vastus medialis obliquus appears to be essential in correcting faulty patellar tracking.