Reliability of three-dimensional gait analysis in cervical spondylotic myelopathy

Gait impairment is one of the primary symptoms of cervical spondylotic myelopathy (CSM). Detailed assessment is possible using three-dimensional gait analysis (3DGA), however the reliability of 3DGA for this population has not been established. The aim of this study was to evaluate the test-retest reliability of temporal-spatial, kinematic and kinetic parameters in a CSM population.

Twelve patients with CSM (mean age 54 years) were consecutively recruited from a neurosurgery clinic. 3DGA was conducted on 2 separate days, less than 1 week apart, using the VICON(®) 250 Motion Analysis. The average of 10 gait cycles was analysed. Reliability was assessed using the one-way random intraclass correlation coefficient (ICC), the standard error of measurement (SEM), and Bland-Altman limits of agreement (LOA).

Temporal-spatial parameters showed excellent reliability, with ICCs above 0.9 for speed, cadence, stride length, double support time, and step width. ICCs for kinematic parameters ranged from acceptable (0.62, peak knee flexion in stance) to excellent (0.95, total hip sagittal plane motion). The SEM for all kinematic parameters was below 4°, with the exception of peak hip internal rotation (5.8°). Peak values were less reliable than the total range of motion in a plane. The majority of kinetic parameters showed excellent reliability (ICCs>0.85), with the exception of peak medio-lateral ground reaction force (ICC 0.12).

This information will enhance the interpretation of gait scores for CSM patients, as an estimate of the change required to exceed measurement error is now available.