Analysis of 3D multi-segment lumbar spine motion during gait and prone hip extension.

Modeling the lumbar spine as a single rigid segment does not consider the relative contribution of regional or segmental motion that may occur during a task. The current study used a multi-segment model to measure three-dimensional (3D) upper and lower lumbar spine motion during walking and prone hip extension (PHE). The degree of segmental redundancy during these movements was assessed by calculating the cross-correlation of the segmental angle time series (R) and the correlation of the segmental ranges of motion (R). All correlation coefficients (R, R) were interpreted as follows: very strong (0.80-1.00), strong (0.60-0.79), moderate (0.40-0.59), weak (0.20-0.39), and very weak (0.00-0.19). Strong/very strong positive R were demonstrated between the two segments in all three planes during PHE and in the transverse plane during walking. Weak/moderate R were demonstrated in the sagittal and frontal planes during walking. Strong/very strong positive R were demonstrated in the transverse plane during PHE, and moderate positive R was demonstrated in the sagittal plane during walking. Non-significant R were demonstrated for all other planes and movements. These results suggest the motion patterns of the upper and lower lumbar regions during walking and PHE are sufficiently distinct to warrant the use a multi-segment model for these movements. It also appears that the degree of redundancy between the upper and lower lumbar regions may be task-dependent.