Leg lengthening of more than 5 cm is a risk factor for sciatic nerve injury after total hip arthroplasty for adult hip dislocation.

Total hip arthroplasty (THA) in patients with high hip dislocation is challenging and technically demanding. Nerve injury is a problem associated with leg lengthening after THA. The purpose of this study was to identify the risk factors for sciatic nerve injury after THA in patients with high hip dislocation. Thirty-seven patients (41 THAs) with Crowe type IV hips were consecutively treated. The average leg lengthening (LL) was 3.2 cm. The average Harris hip score was improved from 57.5 points to 83.1 points at the final follow-up. The clinical outcomes after an average 6.4-years follow-up were satisfactory. Sciatic nerve injury was observed in two joints. LL in the two joints (two patients) with sciatic nerve injury was 5.2 cm and 6.7 cm, respectively. Leg lengthening of >5 cm was a risk factor for sciatic nerve injury. Therefore, leg lengthening of >5 cm should be avoided to prevent sciatic nerve injury.