Three-dimensional lumbar spine vertebral motion during running using indwelling bone pins.

ABSTRACT

STUDY DESIGN: Eight healthy volunteers participated in this observational study. OBJECTIVE: Quantify 3-dimensional motions of the lumbar vertebrae during running via direct in vivo measurement and compare these motions to walking data from the same technique and running data from a skin-mounted technique. SUMMARY OF BACKGROUND DATA Lumbar spine motions in running are only reported in 1 series of articles using a skin-mounted technique subject to overestimation and only instrumented a single vertebra. METHODS: Reflective marker triads were attached to Kirschner wires inserted into the spinous processes of L1-S1. Anatomic registration between each vertebra and attached triad was achieved using spinal computed tomographic scans. Skin-mounted trunk markers were used to assess thoracic motions. Subjects ran several times in a calibrated volume at self-selected speed while 3-dimensional motion data were collected. RESULTS: Lumbar spine flexion and pelvic rotation patterns in running were reversed compared with walking. Increased lumbar spine motions during running occurred at the most inferior segments. Thoracic spine, lumbar spine and pelvis exhibited significantly greater range of sagittal plane motion with running. The pelvis had significantly greater range of frontal plane motion, and the thoracic spine had significantly greater range of transverse plane motion with running. Skin-mounted studies reported as much as 4 times the motion range determined by the indwelling bone pin techniques, indicating that the skin motion relative to the underlying bone during running was greater than the motion of the underlying vertebrae. CONCLUSION: The lumbar spine acts as a distinct functional segment in the spine during running, chiefly contributing lateral flexion to balance the relative motions between the trunk and pelvis. The lumbar spine is also shown to oppose thoracic spine sagittal flexion. While the lumbar spine chiefly contributes to frontal plane motion, the thoracic spine contributes the majority of the transverse plane motion. LEVEL OF EVIDENCE N/A.