Lower peak knee joint kinetics during walking in patients with knee reconstruction for bone sarcoma compared to healthy controls.

Background: Osteosarcoma patients who have undergone prosthetic lower limb reconstruction following tumour resection walk at a slower preferred speed than healthy controls. In addition, they demonstrate lower peak isokinetic knee extension torques, which may explain the observed differences in sagittal plane knee joint kinematics during walking. However, mechanisms for this and the associated knee joint kinetics are not well understood, particularly at matched walking speeds. Methods: This observational case-control study compared sagittal plane lower limb walking gait characteristics between patients who have undergone prosthetic reconstruction and matched healthy controls across their preferred and matched walking speeds. Data were collected from 18 control participants and 17 patients while walking on a force-instrumented treadmill at the different speeds. Spatiotemporal variables, peak knee flexion angle, peak knee extensor moments (torques), and peak knee joint power were compared between groups. Results: Patients walked with a slower preferred speed than the control group. When comparing lower limb gait mechanics at matched speeds, patients demonstrated lower magnitude peak knee extensor moments than the control group, and these differences were greater at faster speeds. At the fastest walking speed, patients also displayed lower peak knee joint power compared to the control group. The differences in knee joint kinetics observed between groups may be due to an inability amongst patients to generate the magnitudes of knee extensor force that the control group can generate.