The relationship between lumbar segmental motion and pain response produced by a posterior-to-anterior force in persons with nonspecific low back pain

Study Design: Cross-sectional. Objective: To investigate the association between lumbar segmental motion and pain response during the application of a posterior-to-anterior (PA) force to the lumbar spinous processes in persons with nonspecific low back pain. Background: Although low back pain is believed to be associated with altered segmental motion of the lumbar spine, the relationship between subjective reports of pain and objective measurements of segmental motion has not been established. Methods and Measures: Thirty-five individuals between 18 and 45 years of age with nonspecific low back pain (less than 3 months' duration) participated. All subjects participated in 2 separate procedures: (1) segmental motion assessment during a PA force application over the lumbar spinous processes using dynamic magnetic resonance imaging (MRI), and (2) pain assessment during a PA force application procedure outside of the MRI environment. Frequency counts were used to determine the lumbar segments that were most painful, and which functional spinal units had the most and least motion. Fisher exact tests were performed to determine if an association existed between the most painful segment and the functional spinal unit with the most or least motion. Results: L5 was deemed the most painful segment in nearly half of the participants (48.1%). The L1-2 and L3-4 functional spinal units most frequently had the most motion (25.9% each) and the L4-5 functional spinal units most frequently had the least motion (29.6%). No association was found between the most painful segment and the functional spinal units with either the most or least motion. Conclusion: The results of this study indicate that an assumption regarding segmental motion cannot be inferred from the pain response when using a PA force application procedure. J Orthop Sports Phys Ther 2005;35:203-209.