REPAIR OF THE DEFECT IN SPONDYLOLYSIS - DURABLE FIXATION WITH PEDICLESCREWS AND LAMINAR HOOKS

Direct repair of a defect in the pars interarticularis was performed w ith use of bone-grafting and internal fixation with a pedicle screw, r od, and laminar hook in order to achieve a higher prevalence of osseou s union than that achieved with commonly used procedures, The configur ation of the head of the screw which is designed to allow it to connec t with the rod at the necessary angle, simplified the placement of the rod, The procedure was performed in sixteen patients who had a bilate ral defect of the pars interarticularis with or without grade-I or II spondylolisthesis, had had failure of non-operative treatment, and had had temporary relief of pain after the area of the defect in the pars interarticularis had been infiltrated with lidocaine, Concomitant deg eneration of a disc was not a criterion for exclusion, The patients we re followed for an average of twenty-five months (range, twenty-four t o twenty-eight months), The average age at the time of the operation w as thirty-two years (range, twelve to sixty years), Six patients had f indings of nerve-root compression on myelography with computerized tom ographic scanning, and the bone spurs overlying the affected nerve roo t around the defect in the pars interarticularis were removed with an ultrasonic osteotome through a small window, The implant was removed a bout one year after the operation, Oblique radiographs showed osseous union in the previous defect bilaterally in all sixteen patients, Thir teen patients were free of symptoms, and three had major improvement w ith occasional low-back pain, None had a complication, such as infecti on, breakage of the implant, or irritation of a nerve root, The method used for direct repair of the defect of the pars interarticularis in these patients proved to be simple and effective, Relief of symptoms a ppeared to depend on decompression of the affected nerve root, if one was involved, and on preoperative prediction of the locus of the sympt oms by infiltration of the pars interarticularis with lidocaine.