Objective: Lumbar segmental instability (LSI) is one subgroup of nonspecific low back pain which its diagnosis has not been clarified. The aim of this study was to present a reliable and novel method for evaluation of lumbar spine kinematics in sagital plane.
Materials & Methods: In this comparative and validity testing study, 15 low back patients suspected to have LSI and 15 matched healthy subjects were recruited. Pulsed digital videofluoroscopy was used to investigate kinematics of lumbar motion segments during flexion and extension movements. Segmental linear transition and angular displacement, and Pathway of Center of Rotation (PICR) were calculated for each lumbar motion segment. Movement pattern of lumbar spine between two groups and during range of motion were compared.Data were analyzed by statistical methods such as:Chi-square,Kolmogroff-Smirnoff, Independent T test avd ANOVA with repeated measurements.
Results: Segmental linear transition was different in patients during both flexion and extension movements at L5-S1 segment (P<0.001). PICR was different in patients for L1 and L5 vertebrae during extension movement (P<0.001). Six patients showed "Delayed-Sequence" movement pattern and were different from others (P<0.001).
Conclusion: Previous studies were unsuccessful to determine differences between LSI patients and healthy subjects. This study determined some differences between two groups during the middle range of lumbar spine. New devices such as digital videofluoroscopy can assist in identifying better criteria to diagnosis of LSI in otherwise nonspecific low back patients in hope of providing more specific treatment.