Controle motor do joelho durante a marcha em sujeitos com e sem dor femoropatelar.

Abstract

The purpose of this study was to investigate onset, amplitude and ratio of electric activity of the vastus medialis oblique (VMO), vastus lateralis oblique (VLO) and vastus lateralis longus (VLL) muscle and the angle of the knee joint flexion at heel strike during walking on a treadmill. Fifteen subjects without (22-SD3 years) and twelve with patellofemoral pain syndrome (21-SD2 years) participated in this study. The subjects walked on a treadmill without and with inclination of 5 degrees for 10 minutes. Eight strides were analyzed for each situation. An eletrogoniometer was used to verify the knee flexion angle and a footswitch sensor to determinate the beginning and the end of each stride. An eletrogoniometer was used to verify the knee flexion and a footswitch sensor to inform the beginning and the end of each stride. The electric activity was recorded by surface electrodes (Ag/AgCl), an EMG device with 8 channels (EMG System of Brazil) and a software of acquisition data (AqDados 7.02.06). The electromyographic (EMG) data was processed by Matlab software, that calculated the onset timing of the muscles, the integral values of EMG signal and the EMG ratio (VMO:VLO and VMO:VLL). Knee flexion angle was significantly less in the subject with patellofemoral pain syndrome when compared with the subjects of control group. In the patellofemoral pain syndrome subjects, the EMG onset of vastus lateralis longus ocurred before that vastus medialis oblique, in contrast no such differences ocurred in the control group both during walking on a flat surface and on an inclined surface.The EMG activity of vastus lateralis longus muscle was significantly greater during walking in graded treadmill in the subjects with patellofemoral pain syndrome in relation to the subjects of the control group. The results also showed that to the electric activity of the vastus lateralis oblique muscles was always less than the electric activity of the vastus medialis oblique and/or vastus lateralis longus muscle in both groups, regardless condition. Furthermore, VMO:VLL and VMO:VLO activity ratios showed no significant differences between groups and conditions. The results of the present study showed that subjects with patellofemoral pain syndrome decreased the angle of the knee joint flexion, increased the EMG activity of the vastus muscles and presented EMG onset of vastus lateralis longus before that vastus medialis oblique during graded treadmill walking, suggesting that 5º of the inclination would not be safe for treatment for patients with patellofemoral pain syndrome. In addtion, findings showed less electric activity of the vastus lateralis oblique muscle in relation to the other stabilizers of patella, suggesting that vastus medialis oblique and vastus lateralis longus muscles maintain patellar alignment while VLO doesn t act as lateral stabilizer of the patella, but it acts in the dynamics of patellofemoral joint during gait.