Department of Mechanical Engineering,Sharif University of Technology
The change of gait pattern and muscular activity following amputation is thought to be responsible for the higher incidence of joint degenerative disorders observed in amputees. Considering the lack of consistent data in the literature, the purpose of the present study was to measure and analyze the spatio-temporal variables, the kinematics and, particularly, the net joint moments of the intact and prosthetic limbs of above knee amputee subjects during walking and to compare the results with those of normals. The gait characteristics of five transfemoral amputees and five normal subjects were measured using videography and a force platform. The human body was modeled as a 2-D sagittal plane linkage consisting of 8 rigid segments and analyzed using rigid body kinematics and inverse dynamics approaches. The results, including the joints flexion angles and normalized net moments, were statistically analyzed. There was a significant difference between the spatio temporal variables of the normal subjects and intact and prosthetic limbs of amputee subjects, but, the difference between the intact and prosthetic limbs of amputees was not statistically significant. The kinematics of the intact limb of the amputee subjects was close to that of the normals, but the prosthetic limb had a much more limited angular motion. The intact limbs of the amputee subjects experienced larger than normal extension hip moment (with a maximum value of 2.08 compared to 1.68 Nm/kg) and flexion knee moment (with a maximum value of 1.84 compared to 1.14 Nm/kg); this is believed to contribute to the articular cartilage lesions. The hip joint of the prosthetic limb of the amputee subjects, on the other hand, experienced lower than normal joint moments (with a maximum value of 0.97 compared to 1.67 Nm/kg), which might contribute to the osteoporosis found in the remainder of the femur.