Effect of the surgical approach on the incidence of nerve injury in patients with Crowe IV hip dysplasia undergoing total hip arthroplasty: a comparison between the direct anterior and the posterior approaches.

BACKGROUND

Nerve injury is a major complication of total hip arthroplasty (THA) in patients with Crowe IV developmental dysplasia of the hip (DDH), and its incidence is influenced by the type of surgical approach used. The aim of this study was to compare the recently developed direct anterior approach (DAA) and the classic posterior approach (PA) regarding the characteristics of nerve injuries in Crowe IV DDH patients.

METHODS

A total of 149 Crowe IV DDH patients who underwent THA were retrospectively included and divided into 2 groups based on surgical approach (DAA: 68 patients and PA: 81 patients). Postoperatively, the nerve injury was evaluated both clinically and electrophysiologically. The incidence, severity and prognosis of nerve injuries and involved nerves were compared and analysed.

RESULTS

The overall incidence of nerve injury was 30.88% (21/68) for the DAA and 29.63% (24/81) for the PA (p = 0.868). The incidence of motor nerve injury (12.35%, 10/81) was higher with the PA than with the DAA (2.94%, 2/68, p = 0.036). The sciatic nerve was more commonly injured when the PA was performed (overall incidence: 27.16% vs. 8.82%, p = 0.004). In contrast, nerve injuries with the DAA mainly affected the femoral nerve (overall incidence: 25.00% vs. 11.11%, p = 0.026). The independent risk factors for symptomatic nerve injury were previous surgical history (OR 7.075) and body mass index (OR 1.598) for the DAA and previous surgical history (OR 9.143), surgical time (OR 1.029) and amount of limb lengthening (OR 1.104) for the PA.

CONCLUSIONS

Patients undergoing THA due to osteoarthritis secondary to Crowe IV DDH can be operated on with a DAA. However, there is an increased incidence of femoral nerve injury when compared to the posterior approach. To prevent symptomatic nerve injury, the DAA should not be used in obese patients and might require more extensive intraoperative soft-tissue release.