Possible role of stresses in inducing spinal stenosis--a long term complication following disk excision.

A three-dimensional finite element model of an intact ligamentous lumbar motion segment (L3-4) was used to predict stresses in the pars interarticularis regions of the modeled vertebral bodies. The changes in stresses following disk excision, as compared to the intact model, also were computed. The predicted results show an increase in stresses in the posterior bony elements following disk excision. In some patients over a long period of time this increase in stresses, in association with other clinical factors, may lead to bony hypertrophy of the structures that surround the nerve roots. Ultimately, over a long period of time the increase in pressure on the entrapped nerve root may induce recurrent pain and other complications reported in the literature.