Introduction Lower-limb amputations often result from vascular or traumatic causes and substantially affects mobility and quality of life. Traditionally, rehabilitation has relied on socket prostheses (SP), but are limited due to discomfort, skin irritation, and inefficient load transfer at the socket-skin interface. Osseointegrated prostheses (OIP) is an alternative, which directly anchors a titanium implant in the residual bone, to which the prosthesis can be attached. This direct connection improves mechanical feedback, comfort, and functional mobility. Research indicates that OIP users demonstrate enhanced proprioception, increased walking efficiency, and greater gait symmetry compared to SP users, although outcomes vary across individuals. Despite this, long-term biomechanical adaptations and objective measures of gait and balance performance have yet to be clearly established. To address this gap, the present study aims to identify biomechanical biomarkers of gait and static balance in transfemoral amputees with an OIP compared to SP and able-bodied controls, using quantitative gait and balance analysis.
Methods This cross-sectional observational study was approved by the Erasmus MC Ethics Committee and conducted in accordance with the Declaration of Helsinki. 13 Participants visited the Erasmus MC for a testing session. Gait and balance were measured with a motion capture system and a dual-belt treadmill with integrated force plates. The CGM 2.5 was used for the marker protocol, with slight adjustments. Tests included walking at self-selected and imposed (1 m/s) speeds, and static balance tasks under three varying sensory and cognitive conditions. OpenSim models of the control and OIP groups were adapted for this study, while the SP model was generated by modifying the OIP model with a socket interface. Marker data and ground reaction forces were recorded and processed in OpenSim 4.5 using personalized models to compute kinematics, kinetics, and spatiotemporal parameters. Additional balance parameters, such as Margin of Stability in gait and Centre of Pressure, were calculated to evaluate balance control and load distribution between the non-affected and affected side.
Results At both imposed and self-selected speeds, OIP users demonstrated gait patterns closer to healthy controls than SP users. Both prosthetic groups exhibited reduced knee flexion during loading and showed asymmetrical stance times, with longer stance on the intact limb. OIP users showed improved load transfer and stability, whereas SP users displayed greater asymmetry, lower cadence, and longer step lengths. Kinematic and kinetic analyses revealed lower ankle push-off and knee flexion moments in both groups, compensated by increased hip and trunk involvement. Margin of Stability values in gait suggested more favourable mediolateral stability in OIP users, while balance trials indicated greater reliance on visual input and non-affected limb loading in SP users.
Conclusion The findings in this study show that osseointegration enhances gait symmetry and stability compared to socket prosthesis, though not fully restoring natural movement. Current compensation strategies highlight the need for focused rehabilitation and further investigation into the long-term functional and musculoskeletal effects of both prosthesis types.