The role of trauma in disc protrusion.

An analysis of the carefully taken histories of 68 patients whose disc lesion was verified at operation showed that 72% of them gave a history of trauma at the onset of backache. The forces involved varied from very great to minimal and 28% had no history of trauma at all. Therefore it is concluded that trauma may be a precipitating but not a primary factor. It is suggested that the primary factor is a painless nuclear herniation into the inner layers of the annulus, which are painless because they have no innervation. Trauma causes the nucleus to rupture into or through the outer five or so innervated layers, precipitating pain and symptoms.