Development and Validation of a New Technique for Assessing Lumbar Spine Motion

Study Design. Dynamic lumbar flexion–extension motions were assessed by an electrogoniometer and a videofluoroscopy unit simultaneously. Objective. To develop and validate a new technique for the assessment of lumbar spine motion. Summary of Background Data. Spine instability, a clinical condition that is common but difficult to diagnose, has been suggested to involve a characteristic change in the relation between vertebrae during motion. Assessment of lumbar instability using functional radiographs is controversial. Information regarding dynamic spine kinematics in vivo is limited. Methods. A lumbar spine motion analysis system was developed, and its reliability was assessed. Simultaneous total flexion range of motion and segmental motion of the lumbar spine were assessed in 30 healthy volunteers. Lumbar images were captured in 10° intervals during flexion–extension. Intervertebral flexion–extension of each vertebral level was calculated. Results. In flexion, the lumbar vertebrae flexed with a descending order from L1 to L5 throughout the motion. Conversely, the concavity of lumbar lordosis increased steadily in extension. No statistically significant difference in the pattern of motion was found between genders. Conclusions. The results from this study showed that the newly developed technique is reliable. It may have potential value for evaluating spine instability in clinical practice.