Direct pars repair techniques for lumbar spondylolysis: a comparative literature review

Lumbar spondylolysis, a pars interarticularis defect affecting approximately 3%-6% of the general population, presents a significant clinical challenge in young adults and athletes. When conservative management fails, direct pars repair offers an attractive alternative to spinal fusion by preserving segmental motion and reducing the risk of adjacent segment degeneration.This narrative review compares seven principal direct pars repair techniques-Buck's technique, Scott's wiring method, Morscher's hook-screw system, pedicle screw-based constructs, the V-rod/U-rod (Gillet technique), the smiley face rod construct, and the dual-stability construct (DSC)-evaluating their biomechanical properties, clinical outcomes, fusion rates, and complication profiles.

A narrative literature review was conducted examining metaanalyses, retrospective cohort studies, and biomechanical investigations published between 1970 and 2024. Primary outcome measures included fusion rates, complication rates, clinical success rates, and biomechanical stability. The inherent heterogeneity of included studies-encompassing varied patient populations, surgical technique modifications, follow-up durations, and outcome definitions-precludes formal metaanalytic synthesis and is addressed in the limitations section.

Pedicle screw-based techniques demonstrated the highest fusion rates (90.2%; N = 240, 14 studies) with complication rates of 12.8% and positive clinical outcomes in 80.1% of patients. Buck's technique showed fusion rates of 83.5% (N = 372, 27 studies) with complications in 13.4% and favourable outcomes in 84.3%. Scott's wiring achieved 81.6% fusion with 22.4% complications. Morscher's hook-screw system demonstrated 77.7% fusion rates (N = 193, five studies) with the highest complication rate at 27.4%. Modern constructs-the V-rod/U-rod, smiley face rod, and DSC-appear to offer comparable or superior outcomes to pedicle screw constructs in selected series. Age below 25 years emerged as the most critical determinant of success across all techniques.

Pedicle screw-based direct pars repair appears to provide the most favourable fusion and complication profile among the classical techniques. Modern constructs (V-rod, smiley face, and DSC) show promising results and warrant prospective evaluation. Buck's technique remains a viable alternative in experienced hands. Morscher's hook-screw system should be reserved as a salvage option when pedicle screw trajectory is anatomically precluded. Patient selection criteria-including age below 45 years, minimal disc degeneration, and absence of significant spondylolisthesis-are central to surgical success.