The case study of prosthetic foot alignment on amputee gait kinematics using IMU-based motion capture system.

The determination of the optimal prosthesis alignment for maximum patient comfort is an important rehabilitation goal, especially for lower limb amputees, where the assessment of biomechanics is complex. Despite this, quantitative gait analysis is rarely used in clinical practice, and the influence of prosthesis alignment on gait kinematics remains unclear. This study explores the use of an IMU-based motion capture system to assess the impact of prosthesis alignment on gait biomechanics. A transtibial amputee's gait was analyzed with various prosthetic foot alignments in the sagittal and frontal planes. Key gait parameters were measured, including joint flexion/extension angles, body tilt and center of mass (COM) oscillation. Deviations in joint angles from reference values reached 30°, and gait speed varied by up to 0.5 m/s depending on alignment. Notably, prosthesis alignment had minimal impact on the healthy leg's kinematics but significantly influenced gait asymmetry, also reflected in COM movement. The study confirms that prosthesis alignment can markedly affect amputee gait biomechanics. The proposed method enables clinicians to evaluate alignment suitability and make data-driven adjustments.