Effects of traction on structural properties of degenerated disc using an in vivo rat-tail model

Study Design. An in vivo rat-tail model was adopted to study the structural changes of degenerated intervertebral disc after different traction protocols. 

Objective. To investigate the effects of traction with different modes and magnitudes on disc with simulated degeneration. 

Summary of Background Data. Traction has been commonly used in clinical practice for treating low back pain. Its effects on disc with degeneration have not been fully investigated. 

Methods. Forty-seven mature rats were used. Continuous static compression of 11 N was applied to the rat caudal 8-9 disc for 2 weeks to simulate disc degeneration. Tractions with different modes (static or intermittent) and magnitudes (1.4 N or 4.2 N) were applied to the degenerated disc for 3 weeks. The disc height was quantified in vivo on days 4, 18, and 39. The treated discs were then harvested for morphologic analysis. 

Results. Significant decrease in disc height with degenerative morphologic changes was observed after the application of the static compression. The changes in disc height after the application of traction were found to be magnitude dependent. Continuous decrease in disc height was observed after 4.2-N traction, whereas the disc height maintained after traction of 1.4 N. However, no obvious morphologic change was found in comparison with the degenerated discs without traction. 

Conclusion. Although traction was not demonstrated to have restored disc with degeneration, traction with relatively low magnitude was found to have significant beneficial effect in maintaining disc height of degenerated disc, and it might be a potential intervention to slow down the process of degeneration. Future studies of the effects of low-magnitude traction on degenerated disc are recommended. Copyright © 2010 Lippincott Williams & Wilkins, Inc.