Femoral loads during gait in a patient with massive skeletal reconstruction

BackgroundBiological massive skeletal reconstructions in tumours adopt a long rehabilitation protocol aimed at minimising the fracture risk. To improve rehabilitation and surgical procedures it is important to fully understand the biomechanics of the reconstructed limb. The aim of the present study was to develop a subject-specific musculoskeletal model of a patient with a massive biological skeletal reconstruction, to investigate the loads acting on the femur during gait, once the rehabilitation protocol was completed.MethodsA personalised musculoskeletal model of the patient's lower limbs was built from a CT exam and registered with the kinematics recorded in a gait analysis session. Predicted activations for major muscles were compared to EMG signals to assess the model's predictive accuracy.FindingsGait kinematics showed only minor discrepancies between the two legs and was compatible with normality data. External moments showed slightly higher differences and were almost always lower on the operated leg exhibiting a lower variability. In the beginning of the stance phase, the joint moments were, conversely, higher on the operated side and showed a higher variability. This pattern was reflected and amplified on the femoral forces where the differences became important: on the hip, a maximum difference of 1.6 BW was predicted. The variability of the forces seemed, generally, lower on the operated leg than on the contralateral one.InterpretationSmall asymmetries in kinematic patterns might be associated, in massive skeletal reconstruction, to significant difference in the skeletal loads (up to 1.6 BW for the hip joint reaction) during gait.