LOWER LIMB FLEXIBILITY AND MUSCLE STRENGTH IN OSGOOD SCHLATTER DISEASE.

Abstract

1819 BACKGROUND: Osgood-Schlatter Disease (OSD) is a result of microavulsions caused by traction of the patellar tendon on the tibial apophysis. We hypothesized that adolescent patients with OSD lack knee flexibility and may have an imbalance of muscle strength in the lower limbs. METHODS: 9 adolescents (mean age=11.8 yrs.) with OSD were matched for age, sex, height and weight with 9 adolescents with no known knee disease. Participants completed a questionnaire about type and frequency of sports participation. Quantitative static flexibility of the hamstring and quadriceps muscles was measured. Isokinetic knee extensor and flexor muscle strength was measured at speeds of 90,180,&360 degrees/second using a Biodex III system dynanometer. Peak torque and total work during isokinetic movement was calculated. RESULTS: A comparison of quadriceps and hamstring flexibility by goniometer between the OSD and control groups showed similar flexibility (mean 127.4 degrees and 129.6 degrees, respectively for quadriceps and 39.8 degrees and 41.2 degrees for hamstrings, p=ns). Subjects in the OSD group who engaged in sports more than three times a week (n=7) were significantly less flexible than the remainder (n=11) of the participants (mean quadriceps flexibility 141.1 degrees vs. 128 degrees, p<0.05). Isokinetic strength testing of bilateral knee extensor and flexor muscle groups was not significantly different between the OSD and control groups. However, the ratio of knee extensor strength to knee flexor strength was greater in affected knees of OSD subjects than in knees of controls. (Mean knee extension/flexion ratio in OSD subjects 73/30 ft.lbs=2.4, in controls 78/42 ft.lbs.=1.85, p<0.05). CONCLUSION: Lack of flexibility and strength imbalance of the leg muscles is associated with OSD. While this cross-sectional study cannot determine cause and effect, training aimed at improving the flexibility and balancing the strength of the leg muscle groups in adolescents may help prevent Osgood-Schlatter disease.