Dynamic measurement of lumbar curvature using fibre-optic sensors.

Dynamic continuous measurement of the curvature of the lumbar spine is technically difficult but could provide important information about the functions of the spine. A new measurement system using a ribbon of specifically modified fibre-optic sensors was attached to the back and used to dynamically measure lumbar surface curvature during flexion and lifting. Reliability of the collected data and comparison to a video-based system were investigated in thirteen participants for curvature of both the lower and whole lumbar spine. The coefficients of multiple correlation of repeated measurements of curvature-time curves were found to be high, 0.97-0.98, and all measurements were as reliable as data obtained by the video method (0.93-0.97). Root mean square error values were below 2.5° for the fibre-optic system. Reattachment reliability was found to be excellent (0.91-0.97) as were comparisons to a video-based method (0.84-0.95). It is concluded that the fibre-optic motion analysis system is capable of reliably measuring sagittal lumbar curvature across time and offers the ability to provide information regarding sequencing and relative motion between specific regions of the lumbar spine.