ankle rotation changes and its influences in knee osteoarthritis

background : biomechanical factors are known to be important in knee osteoarthritis (oa) development and progression. this study was designed to determine changes of hamstrings muscle activation, knee adduction moment and ankle rotation angle in two knee osteoarthritis (mild and moderate) and a healthy control group.   methods: 16 females (10 with mild and 6 with moderate medial knee osteoarthritis) and 10 control matched females were recruited. a 3d gait analysis was performed on the subjects while they walked along the walkway. electromyography data was also collected during gait from lateral and medial hamstrings. post hoc tukey hsd (multi comparison) was performed to compare knee adduction moment, ankle rotation angle and medial and lateral hamstrings activity at early and late stance, between three groups.   results: ankle rotation angle, knee adduction moment and lateral hamstrings activation showed no significant difference between three groups. interestingly, medial hamstrings activity was significantly higher at late stance in moderate group compared with asymptomatic and mild groups ( p =0.03, 0.02 respectively). also knee adduction moment at late stance was significantly and directly correlated with ankle rotation angle, and lateral hamstrings activity at early stance was significantly and inversely correlated with this angle.   conclusions: it can be concluded that, increased lateral hamstrings activity can increase external ankle rotation and consequently decrease knee adduction moment.