A comparison of the innervation characteristics of the lateral spinal ligaments between normal subjects and patients with adolescent idiopathic scoliosis

Evidence is rapidly accumulating to suggest that general proprioceptive dysfunction might be a major contributing factor in the development of adolescent idiopathic scoliosis (AIS). The innervation of appropriate ligaments which has been shown to be involved in proprioceptive feedback mechanisms, has also been suggested to play a part in this sensory dysfunction. Accordingly, this study compared the innervation characteristics of lateral spinal ligaments from patients with AIS to similar measurements from control subjects. Using an antibody to neurofilament protein, Ruffini corpuscles, small and large nerve bundles, and free nerve endings were identified and their numbers and distribution patterns compared. In the control group, the innervation was found to be symmetrical between left and right sides but was more concentrated in the ventral portion of each ligament. No apparent morphological defect of the innervation was found in the lateral spinal ligaments of the scoliosis patients but the innervation densities of Ruffini corpuscles, single nerve fibres and total neural elements were significantly lower (p<0.01) than those found in normal subjects. These results suggest a possible mechanism for the production of AIS and warrant further study.