Direct repair of lumbar spondylolysis by Buck's technique

Abstract

Background: The lesion in spondylolysis is a nonunion that follows a fatigue fracture of pars interarticularis. Direct repair of the pars defect is a logical alternative to fusion as it helps to preserve the motion segment and prevents abnormal stresses at the adjacent levels. The purpose of the study is to analyze the clinical and radiological results of direct screw osteosynthesis of the pars defect by the Buck's method in patients with symptomatic spondylolysis with or without grade 1 spondylolisthesis.

Materials and methods: Nine patients (six males, three females, mean age 24 years) with symptomatic spondylolysis with or without grade 1 spondylolisthesis and a normal disc in magnetic resonance imaging (MRI), who failed conservative treatment, underwent surgery between January 2000 and April 2009. Of them five patients had bilateral lysis at one level, one had bilateral lysis at three levels and two levels each and two had unilateral lysis at one level. Direct pars repair by the Buck's method with internal fixation of the defect using 4.5 mm cortical screws and cancellous bone grafting was done. The mean follow-up period was 45 months. MacNab criteria were used to evaluate the postoperative functional outcome. Healing of the pars defect was assessed by plain radiographs and computed tomography (CT) scan.

Results: Spondylolysis was bilateral in seven and unilateral in two patients. Two patients had associated grade 1 spondylolisthesis. The mean operative time was 58 minutes (range 45 - 75 minutes) and blood loss was 98 ml (50 - 140 ml). Although radiological fusion was observed in all patients at a mean follow-up of 45 months (range 9 to 108 months), the functional outcome was excellent in two patients and good in five, with one fair and one poor result. The overall result of the procedure was satisfactory in 78% (7/9) of the patients. The two patients with associated grade 1 spondylolisthesis had fair and poor results. No complications were encountered in the perioperative or postoperative period.

Conclusions: In carefully selected patients, direct repair of the pars defect by the Buck's technique of internal fixation and bone grafting was a safe and effective alternative to fusion in younger patients with symptomatic spondylolysis, without associated spondylolisthesis, who failed conservative management.

Keywords: Buck’s technique; direct pars repair; pars interarticularis; spondylolysis.

Figure 1

(a) Preoperative lateral radiograph and (b) axial CT scan showing unilateral defect of the pars interarticularis of the L4 vertebra. (c) Sagittal T2 weighted MRI demonstrating the normal L4-L5 disc without any degeneration. Follow-up lateral dynamic radiographs in (d) flexion and (e) extension, showing complete healing of the defect without signs of instability. (f) Postoperative axial CT scan demonstrating complete healing of the spondylolytic defect

Figure 2

(a) Preoperative lateral radiograph and (b) follow-up lateral radiograph of a patient with bilateral spondylolysis of L5 fixed by Buck’s technique on both sides. (c) Preoperative and (d) follow-up axial CT scan of the same patient showing complete healing of the pars defect bilaterally, without signs of screw loosening, back out, or breakage

Figure 3

(a) Preoperative lateral radiograph of a patient with triple level spondylolysis at L2, L3, and L5. (b) Postoperative follow-up lateral and (c) anteroposterior radiographs showing good healing of the pars defect at all three levels