Repair of pars defects by segmental transverse wiring for athletes with symptomatic spondylolysis: relationship between bony union and postoperative symptoms.

STUDY DESIGN: Retrospective study of surgery for spondylolysis patients.

OBJECTIVE: To assess clinical outcome of bony union using multislice computed tomography after segmental wiring fixation.

SUMMARY OF BACKGROUND DATA: How bony union affects surgical outcome of spondylolysis repair is unclear.

METHODS: Forty-four athletes with symptomatic spondylolysis (33 men and 11 women; mean age, 24.2 ± 5.4 years) who underwent segmental wiring fixation were evaluated retrospectively at a mean follow-up of 85 ± 17 months. The level of spondylolysis was L5 in 42 cases, and both L4 and L5 in 2 cases, giving a total of 46 operative levels of vertebrae. Bony union using axial and sagittal reconstruction images of computed tomography, the Japanese Orthopaedic Association (JOA) score for back pain, and complications were reviewed. State of bony union was classified as bilateral union, unilateral union, or nonunion. The total score and the improvement ratio of the JOA score were compared among the 3 groups.

RESULTS: Bilateral bony union was obtained in 29 cases (31 of 46 vertebrae, 67.4%). Six cases (13%) showed unilateral union, and 9 cases (19.6%) showed nonunion. JOA score increased significantly after surgery in all groups, average improvement rate was 78.9% in the bilateral group, 63.6% in the unilateral group, and 29.8% in the nonunion group; differences among the 3 groups were significant (P < 0.05). JOA score was significantly higher in the bilateral group than in the other 2 groups.

CONCLUSION: Although symptoms were significantly ameliorated in all groups, the bilateral group showed the greatest improvement ratio in JOA score showing bony union to be an important factor in clinical outcome. However, there were a few exceptional cases with contradictory clinical and radiological outcomes. Thus, further studies are required to gain a better understanding of the other multiple factors affecting clinical outcome after spondylolysis repair.