Combined neurosurgical-orthopedic approach to the correction of radiculopathy and instability in spondylolysis and spondylolisthesis.

The authors give a brief review of the pathologic anatomy, the incidence and distribution, the probable etiologic factors in the development of spondylolysis and spondylisthesis, and a description of the clinical syndrome of this abnormality. It is pointed out that there are two distinct parts to the clinical syndrome: back pain due to instability of the isthmic defect and/or radiculopathy due to direct compression of the lumbar nerve root in its course immediately beneath the osteocartilaginous deformity which is the primary pathologic feature of this disorder. It is suggested that the variable benefits of the several operative procedures advocated for this disorder are largely related to fortuitous removal of some of the osteocartilaginous deformity and/or stabilization of the isthmic defects. Other writers have advocated fusion as a necessary part of any operative intervention for the treatment of spondylolysis. The authors here agree with this viewpoint and in addition, feel that complete and precise removal of the isthmic deformity is an equally imperative part of such surgery. While the principles of isthmic decompression combined with fusion are not innovative, the operative technique described here is innovative, simple, and precise, and has been followed by a high rate of excellent results.