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