The Interaction of Knee, Hip and L5-S1 Joint Contact Forces and Spatiotemporal Variables Between Sound and Prosthetic Leg in Patients with Unilateral Below-Knee Amputation During Walking

Background: There is little knowledge that explains how forces are applied on knee, hip and L5-S1 joint between the sound and prosthetic leg in unilateral Below-Knee Amputation (BKA), therefore the aim of this study was to assess the interaction of knee, hip and L5-S1 joint contact forces between sound and prosthetic leg in patients with unilateral BKA during walking. Methods: Five patients with BKA were recruited in this study. A Qualisys motion system captured with seven cameras and a Kistler force plate were used to record kinematics and kinetics variables of walking. The forces applied on knee, hip and L5-S1 joint contact forces (JCF) were calculated by using Open- SIM software. SPSS software was used to analyze data at an alpha set point of 0.05. Results: The propulsive and second peaks of ground reaction forces applied on sound leg were significantly higher than on prosthetic leg (P<0.05). Although the forces applied on hip, knee and L5-S1 joint in the sound leg were higher compared to prosthetic leg, the interaction between side and joint factor was not significant (P>0.05). Conclusion: The results of this study showed that the meaningful JCF applied on the sound leg was more than that of prosthetic leg. Insignificant increases in JCF on the sound leg during life can create cumulative forces on the knee and low-back and endanger these joints of the risk of knee OA and chronic low-back pain. Balanced forces applied on sound and prosthetic leg is important, if this is the case, so indicating using a proper application of socket pin and prosthetic feet may have beneficial impact on sound side loads.