Inferior gluteal nerve morbidity in acetabular fracture fixation: a comparative analysis of the Kocher-Langenbeck and Gibson approaches.

OBJECTIVES

To compare inferior gluteal nerve morbidity and functional outcomes between the traditional muscle-splitting Kocher-Langenbeck approach and the muscle-sparing Gibson (extended posterior) approach in acetabular fracture fixation.

METHODS

Design

Prospective cohort study.

SETTING

Single Level 1 Trauma Center. Patient Selection Criteria: Patients presenting within 2 weeks of sustaining an acetabular fracture (AO 62 A/ 62B/ 62 C) requiring surgical fixation via a posterior approach including polytrauma were eligible for inclusion. The exclusion criteria were prior hip pathology and prior hip surgery on the affected side. Outcome Measures and Comparisons: The primary outcome compared was inferior gluteal nerve morbidity assessed by electromyography (EMG) at 3 and 6 months postoperatively. Secondary outcomes included gluteus maximus muscle volume difference by magnetic resonance imaging (MRI) done preoperatively and at 3 months, objective muscle strength using a custom load cell system and functional scores (Harris Hip Score and Merle d'Aubigné-Postel score) at 3 and 6 months.

RESULTS

Significant inferior gluteal nerve denervation was detected at 3 months in 5 of 6 patients (83%) treated with the Kocher-Langenbeck approach compared to 0 of 7 patients (0%) treated with the Gibson approach (p = 0.002). All denervation injuries resolved by 6-month follow-up. The study was not powered to compare secondary outcomes; differences between groups in muscle volume loss (296 cc vs. 254 cc, p = 0.521), muscle power (113 ± 19.69 newtons vs. 130 ± 58.67 newtons, p = 0.566) and Harris Hip Score improvement (42.5 ± 3.6 vs. 33.5 ± 10.4, p = 0.103) were not statistically significant, but confidence intervals were wide and clinically important differences cannot be excluded.

CONCLUSION

In this small non-randomised cohort, the muscle-sparing Gibson approach was associated with a lower rate of transient inferior gluteal nerve denervation than the Kocher-Langenbeck approach, with complete electrophysiological recovery by 6 months in all affected patients. Each approach was performed by a different surgeon, and the study was not powered to compare functional outcomes or muscle volume, and differences of clinical importance cannot be excluded. These findings suggest that the Gibson approach may reduce inferior gluteal nerve morbidity and warrant evaluation in a larger multi-surgeon study.

LEVEL OF EVIDENCE: Therapeutic Level II.