Background: Whether vastus medialis obliquus atrophy exists in patients with patellofemoral pain syndrome and whether the amount of atrophy differs between the vastus medialis obliquus and vastus lateralis muscles remain unknown.
Materials: From June 2016 to March 2019, 61 patients with patellofemoral pain syndrome were retrospectively included in the study group, and an age-, sex-, and body mass index-matched cohort of 61 patients with normal knees was randomly selected as the control group. All enrolled subjects had undergone CT scans in the supine position. The cross-sectional areas of the vastus medialis obliquus and the vastus lateralis muscle in the sections 0, 5, 10, 15, and 20 mm above the upper pole of the patella were measured, and the vastus medialis obliquus/vastus lateralis muscle area ratio was evaluated.
Results: In the study group, the vastus medialis obliquus areas and the vastus lateralis muscle areas in the sections that were 0, 5, 10, 15, and 20 mm above the upper pole of the patella were significantly smaller than the respective areas in the control group (P < 0.05). The vastus medialis obliquus/vastus lateralis muscle area ratio was significantly smaller at the upper pole of the patella (the section 0 mm above the upper pole of the patella) than the corresponding ratio in the control group (P < 0.05). No significant difference was noted between the two groups in the sections 5, 10, 15, and 20 mm above the upper pole of the patella (P > 0.05).
Conclusion: In patients with patellofemoral pain syndrome, vastus medialis obliquus and vastus lateralis muscle atrophy existed in sections 0-20 mm above the upper pole of the patella, compared with normal controls, and atrophy of the vastus medialis obliquus was more evident than that of the vastus lateralis muscle at the upper pole of the patella. These findings support the rationale for the use of general quadriceps exercise combined with vastus medialis obliquus strengthening exercise as part of the rehabilitation programme for the patients with patellofemoral pain syndrome.
Keywords: Computed tomography; Patellofemoral pain syndrome; VMO/VLM area ratio; Vastus lateralis muscle; Vastus medialis obliquus.