Motion segment-sparing repair of symptomatic chronic pars defects

The current standard of care for symptomatic chronic spondylolysis (SP) is a one-level posterior spinal fusion for defects at L-5 or direct pars repair (motion segment sparing) for more rostral SP in younger patients and if no disc degeneration or listhesis is present. Since many patients with SP undergoing operative repair are young, a procedure with the lowest biomechanical profile is desirable, and direct pars repair is recommended. The authors here explore the limits of direct pars repair.

A retrospective review of all patients who underwent direct repair of SP between 2002 and 2009 was performed. Data were analyzed for predictors of symptom relief and radiographic fusion failure.

Of 49 patients, only 7 required a reoperation to treat clinical symptoms, and 6 of them were female (p = 0.049). In all cases of treatment failure, the patient had bilateral L-5 SP. Patients with a slip percentage as high as 30% experienced radiographic fusion and symptom relief. Disc degeneration (measured using the Modified Pfirrmann Scale) did not predict symptom persistence or radiographic fusion failure. Patients with high-grade disc disease experienced symptom relief. The authors found no predictors of treatment failure.

The number of patients undergoing motion segment-sparing fusions of symptomatic chronic SP can be safely increased to include patients with Grade I spondylolisthesis as well as high-grade disc disease. Female patients with bilateral L-5 SP and low lordotic angles may be better served by a posterior spinal fusion from L-5 to S-1.