Alterations of gait kinematics depend on the deformity type in the setting of adult spinal deformity

Purpose To evaluate 3D kinematic alterations during gait in Adult Spinal Deformity (ASD) subjects with different deformity presentations. Methods One hundred nineteen primary ASD (51 +/- 19y, 90F), age and sex-matched to 60 controls, underwent 3D gait analysis with subsequent calculation of 3D lower limb, trunk and segmental spine kinematics as well as the gait deviation index (GDI). ASD were classified into three groups: 51 with sagittal malalignment (ASD-Sag: SVA > 50 mm, PT > 25 degrees, and/or PI-LL > 10 degrees), 28 with only frontal deformity (ASD-Front: Cobb > 20 degrees) and 40 with only hyperkyphosis (ASD-HyperTK: TK > 60 degrees). Kinematics were compared between groups. Results ASD-Sag had a decreased pelvic mobility compared to controls with a decreased ROM of hips (38 vs. 45 degrees) and knees (51 vs. 61 degrees). Furthermore, ASD-Sag exhibited a decreased walking speed (0.8 vs. 1.2 m/s) and GDI (80 vs. 95, all p < 0.05) making them more prone to falls. ASD-HyperTK showed similar patterns but in a less pronounced way. ASD-Front had normal walking patterns. GDI, knee flex/extension and walking speed were significantly associated with SVA and PT (r = 0.30-0.65). Conclusion Sagittal spinal malalignment seems to be the driver of gait alterations in ASD. Patients with higher GT, SVA, PT or PI-LL tended to walk slower, with shorter steps in order to maintain stability with a limited flexibility in the pelvis, hips and knees. These changes were found to a lesser extent in ASD with only hyperkyphosis but not in those with only frontal deformity. 3D gait analysis is an objective tool to evaluate functionality in ASD patients depending on their type of spinal deformity.