Introduction: The modified Stoppa approach for acetabular fractures has become popular. However, the possibility of injury to the obturator nerve with this approach has not been sufficiently considered. We have experienced a case of nerve entrapment in severely displaced fractures. Therefore, we performed a retrospective study to: (1) evaluate the incidence of obturator nerve injury in the modified Stoppa approach for acetabular fractures; (2) analyze the relationship between the extent of displacement of the quadrilateral plate and injury to the obturator nerve.
Hypothesis: We hypothesized that obturator nerve injury would be related to a marked medial displacement of the quadrilateral plate.
Patients and methods: We conducted a retrospective cohort study of 22 patients with acetabular fractures that were surgically treated with the modified Stoppa approach. The medial displacement of the quadrilateral plate was measured on a three-dimensional reconstruction image with the inlet view. Postoperative electrodiagnostic tests were performed based on clinical suspicion of neurological injury. Nerve injuries were divided into initial trauma or postoperative complication, and recovery of nerve function was evaluated. We identified the incidence of obturator nerve injury and analyzed the relationship between obturator nerve injury and medial displacement of the quadrilateral plate.
Results: The incidence of obturator nerve injury was 2/22 (9.1%), and all injuries resulted from the initial trauma. The average displacement of the quadrilateral plate was 15.9±13.4mm. Patients were divided into two groups, using a displacement of 24mm as a cutoff point, identified using a receiver operating characteristic curve analysis. There were 16 patients in group 1 (<24mm) and 6 patients in group 2 (≥24mm). The incidence of obturator nerve injury from trauma was 0/16 (0%) in group 1 and 2/6 (33.3%) in group 2 (P=0.018).
Conclusions: No cases of postoperative obturator nerve injury were identified. Preoperative obturator nerve injury was more common in patients with a displacement of the quadrilateral plate≥24mm.
Level of evidence: IV, retrospective study.
Keywords: Acetabular fracture; Acetabulum; Approach; Complications; Obturator nerve.
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