Three-dimensional Evaluation of Gait: Kinetics, Kinematics, and Electromyographic in Patients with Mucopolysacharidosis Types IV and VI.

This study evaluated and determined, through instrumented three-dimensional (3D) gait analysis, the kinetic, kinematic, and electromyographic profile of patients with mucopolysaccharidosis (MPS) IV and VI.  This crossectional study included 11 patients treated at a rare diseases reference service and evaluated in a movement analysis laboratory. We collected clinical, physical examination, and kinetic, kinematic, and electromyographic data using a 3D movement system, from June 2020 to January 2021.  There were 5 (45.5%) female patients, and 6 (54.5%) males. Furthermore, 9 (81.8%) subjects had MPS VI, and 2 (18.2%) had MPS IV. Their average age was 14.6 years. The average speed was 0.68 m/s (±0.21), and the stride length was 0.66 (±0.15). The most altered static angles were the hips' abduction-adduction, knees' range of movement, and foot's progression angle. Most cases presented a gait pattern of hip flexion-adduction and knee flexion. The gait profile scale (GPS) was 14.58 (±6.72) on the right side and 11.71 (±3.39) on the left. The gait deviation index (GDI) was 73.23 (±14.50) on the right side and 80.45 (±17.05) on the left. Muscle activity approximately followed the current model.  The patients showed a decreased average speed and stride length. Most cases presented a gait pattern of hip flexion-adduction and knee flexion. Both GPS and GDI showed a significant deviation from normality.