Surgical repair of pars defects in spondylolysis

Direct repair of the pars interarticularis defect was carried out in 16 spondylolysis patients. There were 8 male and 8 female patients. The site of pars defects involved L5 in 10 cases and L4 in 6 cases. Chronic low back pain was the main symptom, only one patient presented with acute severe back pain. Pars defects were confirmed by oblique views of the lumbosacral spine. The height of the spinous process of the involved vertebra was measured and compared to the above adjacent vertebra. Radiographic fusion of the defects was confirmed by bridging of bone across the pars on oblique views. All the patients except one were treated conservatively prior to surgery. Clinical outcomes were assessed by pre- and post-operative pain, union of the pars defects, functional status and patient verbal rating scales. The mean follow-up was 36 months, the longest was 7 years. At 2 years follow-up, the overall satisfaction and improvement were reported in most of the patients. There was no functional failure. Hypoplasia of the neural arch was found in 3 patients. There were two non unions, both of them had maldevelopment of neural arches. One symptomatic non union needed resurgery for stabilization.