Pathological trunk motion during walking in children with amyoplasia: is it caused by muscular weakness or joint contractures?

The aim was to investigate the causes for pathological trunk movements during gait in children with Amyoplasia. Eighteen children with Amyoplasia were compared with 18 typically developed children. Three-dimensional motions of pelvis, thorax and spine during gait were analyzed. Excessive trunk movements were defined as being above 4 standard deviations of those of typically developed children. Clinical examination of active strength and passive range of motion of the hip, knee and ankle joints were correlated to the parameter that showed the greatest prevalence of pathological trunk motion. The greatest prevalence of 56% was seen for thorax obliquity range during walking. The spine angles showed the lowest deviations from typically developed children. Significant correlations (p<0.001) between thorax obliquity range and clinical parameters were found for passive hip extension, hip flexion, hip abduction and active hip extension, hip flexion and ankle dorsiflexion strength. The highest correlation coefficients were found for passive hip flexion and active hip flexion strength of rho=-0.73 and rho=-0.69 respectively. Excessive thorax obliquity during gait in children with Amyoplasia could be mainly caused by reduced strength and mobility of the hip. Therefore both mobility and strength of the hip are equally important and should be increased in the therapy to improve gait in children with Amyoplasia.