Assessment of dynamic balance during walking in patients with adult spinal deformity

Purpose To assess dynamic postural alignment in ASD during walking using a subject-specific 3D approach. Methods 69 ASD (51 +/- 20 years, 77%F) and 62 controls (34 +/- 13 years, 62%F) underwent gait analysis along with full-body biplanar Xrays and filled HRQoL questionnaires. Spinopelvic and postural parameters were computed from 3D skeletal reconstructions, including radiographic odontoid to hip axis angle (ODHA) that evaluates the head's position over the pelvis (rODHA), in addition to rSVA and rPT. The 3D bones were then registered on each gait frame to compute the dynamic ODHA (dODHA), dSVA, and dPT. Patients with high dODHA (> mean + 1SD in controls) were classified as ASD-DU (dynamically unbalanced), otherwise as ASD-DB (dynamically balanced). Between-group comparisons and relationship between parameters were investigated. Results 26 patients were classified as ASD-DU having an average dODHA of 10.4 degrees (ASD-DB: 1.2 degrees, controls: 1.7 degrees), dSVA of 112 mm (ASD-DB: 57 mm, controls: 43 mm), and dPT of 21 degrees (ASD-DB: 18 degrees, controls: 14 degrees; all p < 0.001). On static radiographs, ASD-DU group showed more severe sagittal malalignment than ASD-DB, with more altered HRQoL outcomes. The ASD-DU group had an overall abnormal walking compared to ASD-DB & controls (gait deviation index: 81 versus 93 & 97 resp., p < 0.001) showing a reduced flexion/extension range of motion at the hips and knees with a slower gait speed and shorter step length. Dynamic ODHA was correlated to HRQoL scores. Conclusion Dynamically unbalanced ASD had postural malalignment that persist during walking, associated with kinematic alterations in the trunk, pelvis, and lower limbs, making them more prone to falls. Dynamic-ODHA correlates better with HRQoL outcomes than dSVA and dPT.