Reliability and validity of gait dynamic balance assessment in adult spinal deformity patients using a two-point trunk motion measuring device.

BACKGROUND CONTEXT: Adult spinal deformity (ASD) patients often complain of walking discomfort. However, dynamic balance evaluation methods of gait in ASD have not been well established. DESIGN: Case series study. PURPOSE: Characterize the gait of ASD patients using a novel two-point trunk motion measuring device. PATIENT SAMPLE: Sixteen ASD patients scheduled for surgery and 16 healthy control subjects. OUTCOME MEASURES: Trunk swing width and track length of the upper back and sacrum. METHODS: Gait analysis was performed using a two-point trunk motion measuring device on 16 ASD patients and 16 healthy control subjects. Three measurements were taken for each subject, and the coefficient of variation was determined to compare measurement accuracy between the ASD and control groups. Trunk swing width and track length were measured in three dimensions for comparisons between the groups. The relationship among output indices, sagittal spinal alignment parameters, and quality of life (QOL) questionnaire scores was examined as well. RESULTS: No significant difference was found for the precision of the device between the ASD and control groups. Compared with controls, the walking style of ASD patients tended to have larger right-left swing of the trunk (+14.0 cm and +23.3 cm at the sacrum and upper back, respectively), larger horizontal plane movement of the upper body (+36.4 cm), less vertical movement (-5.9 cm and -8.2 cm up-down swing at the sacrum and upper back, respectively), and longer gait cycle (+0.13 sec). Regarding QOL in ASD patients, greater right-left/front-back swing of the trunk, greater movement in the horizontal plane, and longer gait cycle were associated with lower QOL scores. Conversely, greater vertical movement was associated with higher QOL. CONCLUSIONS: ASD patients had unique gait characteristics, the intensity of which were associated with diminished QOL. The two-point trunk motion measuring device may be reliable and useful for the clinical assessment of balance during gait in ASD patients.