Patellar malalignment treated with modified knee extension training: An electromyography study.

BACKGROUND Patellar malalignment (PM) in most patients is ascribed to an imbalance of peripatellar soft tissue tension. RESEARCH QUESTION Conservative treatment of PM initially with enforced training of the vastus medialis obliquus (VMO) has been widely applied. Non-operative techniques for treatment of PM require continuing development. METHODS Thirty healthy young adults participated in the study. Two surface electromyography (EMG) electrodes were placed on the skin of the dominant lower thigh in each subject: one on the center of the muscle belly of the VMO and the other on the symmetric location of the vastus lateralis (VL). Maximum of knee extension action (from various angles of knee flexion to full extension) was initiated. Tests were conducted with knee flexion decreasing by 10° at each step. Each action was repeated three times, and the average value was calculated. The root mean square value of excited muscles in the EMG was recorded. The ratio of the VMO to the VL (VMO/VL) was used to indicate the effectiveness of the treatment. The knee position varied from 90° flexion initially, decreasing by 10° at each step. RESULTS Nine sets of values were obtained. All extension actions were effective (VMO/VL >1; range, 1.23-1.35). The maximal value was observed at 60° flexion (VMO/VL = 1.35). Differences were not significant among the nine groups (p = 0.08, ANOVA). SIGNIFICANCE Using the described knee extension training for conservative treatment of PM may be an effective alternative. The technique is simple, and the results of our experimental tests are encouraging. This method may become another popular and effective technique for treating PM.