IntroductionThe vastus medialis oblique (VMO) is thought to be implicated in patellofemoral pain (PFP), and weakness in this portion of the vastus medialis muscle may lead to PFP. Management includes physiotherapy to strengthen the VMO. Although this intervention has been shown to be effective, the effects on the architecture of the muscle have not been investigated. This study aims to determine the changes in VMO architecture following a program of strengthening exercises. Materials and MethodsTwenty-one male participants underwent an initial ultrasound scan to measure the fibre angle and the insertion level of the VMO on the patella. Each subject then undertook a 6-week quadriceps strengthening program; the scan and measurements were then repeated. ResultsA significant increase in VMO fibre angle and insertion length was observed. Average fibre angle increased by 5.24°; average insertion length increased by 2.7 mm. There was found to be a significant negative correlation between the initial values and the degree of change. Pearson's coefficient of correlation for measurements of patella length taken before and after exercise was 0.921, indicating a high degree of reliability. There was a significant positive correlation between fibre angle change and declared level of compliance (R 2 = 0.796). Conclusions 2The results reported here indicate that physiotherapy leads to a significant change in VMO morphology. Given the inverse correlation noted between initial architectural parameters and the degree of change, we suggest that patients who would benefit most from physiotherapy can be identified in clinic using a simple ultrasound technique.

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There is thought to be a relationship between the vastus medialis oblique muscle (VMO) and patellofemoral pain syndrome (PFPS), a condition that has a high prevalence in young athletic individuals. Following a suggestion that there may be a link between the architecture of the VMO and an individual's activity level, the aim of this study was to determine any differences in two measurable parameters of the VMO between two populations with widely differing activity levels. The parameters measured were VMO fiber angle and insertion ratio, which is the proportion of the medial patellar border with VMO fibers inserting onto it (%). Eighty-two knees from 26 athletic volunteers and 15 sedentary volunteers (aged 20-28 years) were assessed using ultrasound. Activity level was defined using the Tegner scoring system. The mean VMO angle (°) for the athletic group was significantly higher than for the sedentary group at 67.8° and 53.6°, respectively. There was no significant difference in insertion ratio between the athletic group, 43.0%, and the sedentary group, 39.5%. This study found that greater VMO fiber angles were seen in individuals with higher activity levels, exerting a stronger medial stabilizing force on the patella. This has important implications for the treatment of PFPS, particularly in athletic patients, which frequently focus on VMO strengthening exercises.