The effect of neck and leg flexion and their sequence on the lumbar spinal cord. Implications in low back pain and sciatica.

STUDY DESIGN

Fresh cadavers of five baboons were used to assess lumbar spinal cord movement. Window dissection at the L3 level was performed to observe the relative displacement of the cord to bony landmark, when the neck and hip were moved.

OBJECTIVES

To examine the effect of the neck and hip flexion alone and in combination on the movements of the lumbar spinal cord relative to the third lumbar vertebral body. To investigate also the effect of the sequence of flexions.

SUMMARY OF BACKGROUND DATA

Several clinical studies claim that cervical flexion together with straight leg raise tensions the lumbar nerve root. Although previous studies describe the effect of each of these movements, there have been no measurements of the combined effect or the effect of the sequence of movements.

METHODS

Five fresh baboon cadavers were dissected to expose the L3 nerve root. The movement of the lumbar cord at that level was measured relative to a pin on the L3 vertebra. The neck and leg of the cadavers were moved by two operators.

RESULTS

Cervical flexion always moved the lumbar cord in a cephalad direction. The degree of displacement was more pronounced if the cervical flexion followed hip flexion rather than hip extension. Hip flexion also moved the lumbar cord in a cephalad direction. However, the difference in cord displacement attributable to different sequences in hip movements were not found to be statistically significant. Cervical flexion elicited a greater cord displacement than traction.

CONCLUSION

These findings would advocate that a test that comprises both neck and hip movements would be more sensitive in assessing nerve root movements than one that only uses neck or hip movements. Such a test should also consider the use of various sequences of neck and hip movements.