ABSTRACT
BACKGROUND: A common treatment for patients with patellofemoral pain syndrome (PFPS) is strength (force-generating capacity) training of the vastus medialis oblique muscle (VMO). Hip adduction in conjunction with knee extension is commonly used in clinical practice; however, evidence supporting the efficacy of this exercise is lacking. OBJECTIVE: The objective of this study was to determine the surplus effect of hip adduction on the VMO. DESIGN: This study was a randomized controlled trial. SETTING: The study was conducted in a kinesiology laboratory. PARTICIPANTS: Eighty-nine patients with PFPS participated. INTERVENTION: Participants were randomly assigned to 1 of 3 groups: hip adduction combined with leg-press exercise (LPHA group), leg-press exercise only (LP group), or no exercise (control group). Training consisted of 3 weekly sessions for 8 weeks. MEASUREMENTS: Ratings of worst pain as measured with a 100-mm visual analog scale (VAS-W), Lysholm scale scores, and measurements of VMO morphology (including cross-sectional area [CSA] and volume) were obtained before and after the intervention. RESULTS: Significant improvements in VAS-W ratings, Lysholm scale scores, and VMO CSA and volume were observed after the intervention in both exercise groups, but not in the control group. Significantly greater improvements for VAS-W ratings, Lysholm scale scores, and VMO volume were apparent in the LP group compared with the control group. There were no differences between the LP and LPHA groups for any measures. LIMITATIONS: Only the VMO was examined by ultrasonography. The resistance level for hip adduction and the length of intervention period may have been inadequate to induce a training effect. CONCLUSIONS: Similar changes in pain reduction, functional improvement, and VMO hypertrophy were observed in both exercise groups. Incorporating hip adduction with leg-press exercise had no impact on outcome in patients with PFPS.
Subject(s)
Exercise Therapy/methods , Hip Joint/physiopathology , Knee Joint/physiopathology , Patellofemoral Pain Syndrome/physiopathology , Patellofemoral Pain Syndrome/rehabilitation , Torque , Weight-Bearing , Adult , Electromyography , Female , Humans , Male , Middle Aged , Muscle, Skeletal/physiopathology , Pain Measurement/methods , Range of Motion, Articular , Single-Blind MethodABSTRACT
BACKGROUND: It has been assumed that patellofemoral pain syndrome results from patellar malalignment. The precise role the vastus medialis obliquus plays in mediating the underlying pathologic abnormality is unclear. HYPOTHESIS: The morphologic characteristics of the vastus medialis obliquus correlate to patellar malalignment in patients with patellofemoral pain syndrome. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: One hundred twelve patients with patellofemoral pain syndrome were studied. Six sets of computed tomography axial images were assessed in which knee flexion was 0 degrees, 15 degrees, or 30 degrees and the quadriceps muscle either relaxed or contracted. Measurements of serial cross-sectional areas of the vastus medialis obliquus and patellar malalignment were made. Correlation and stepwise regression models between the vastus medialis obliquus variables and patellar malalignment (lateral shift and patellar tilt) were calculated. Statistics were calculated on 4 subgroups depending on patellofemoral malalignment type. RESULTS: Significant correlations were found between measures of cross-sectional areas of vastus medialis obliquus and patellar tilt at 0 degrees and 30 degrees of knee flexion. Using a regression model, it was determined that vastus medialis obliquus is predictive of patellar tilt (R(2) = 0.078-0.130). This explanation was most apparent in the subgroup of patients with extreme patellar tilt and lateral shift malalignments (R(2) up to 0.824). CONCLUSION: There are significant correlations between vastus medialis obliquus variables and patellar malalignments in extended knees of patients with patellofemoral pain syndrome. CLINICAL RELEVANCE: Vastus medialis obliquus muscle function is important to consider in the rehabilitation of patients with patellofemoral pain syndrome, especially those with extreme patellar tilt and lateral shift malalignments.
