NEW TECHNIQUE FOR SPONDYLOLYSIS REPAIR: A PROSPECTIVE STUDY

Abstract

We describe the clinical results of a new technique of direct pars repair stabilised with a construct that consists of a pair of pedicle screws connected with a modular link that passes beneath the spinous process. Tightening the link to the screws compresses the bone grafted pars defect providing rigid intrasegmental fixation.

14 patients aged between 10 and 17 years were included in this study. 7 were males and 7 females. Each of the patients had high activity levels and suffered from significant back pain without radicular symptoms or signs. All patients had undergone at least 12 months of activity modification, a trial of bracing and physical therapy before surgical options were discussed. None of the patients had spondylolisthesis. Definitive pseudo-arthrosis and fracture were confirmed via computerize tomography (CT). Magnetic resonance imaging was performed in every patient to assess the adjacent disc spaces which demonstrated normal signal intensity. The pars defect was at L5 in all 14 patients.

A midline incision was used for surgery. The pars intercularis defect was exposed and filled with autolo-gous iliac crest bone graft prior to screw insertion. After screw insertion, a link was contoured to fit, and placed just caudal to the spinous process, deep to the interspinous ligament of the affected level, and attached to each pedicle screw. There was early mobilization post-operatively without a brace.

The average inpatient stay was 3 days. Post-operative complications included 1 superficial wound haematoma. Follow-up was at 6 weeks, 6 months and at 1 year. At the latest follow-up, visual analogue scores ranged between 0 and 4 for all patients, indicating excellent overall pain control. Functional assessments for all patients via the modified Oswestry scores were 0% to 13%, indicating a good overall functional result. All patients had radiographs at follow-up which showed fusion rates of 80% in those patients followed up for 1 year.

This new technique for direct pars repair demonstrates high fusion rates in addition provides the possible benefits of maintaining adjacent level motion. Clinically this group had good-to excellent functional outcomes as indicated by visual analogue scales and the Oswestry Disability Index.