Novel Technique for Intra-Operative Sciatic Nerve Assessment in Complex Primary Total Hip Arthroplasty: A Pilot Study

Introduction: Sciatic nerve injury (SNI) is a potentially devastating complication after total hiparthroplasty (THA). Intra-operative neural monitoring has been found in several studies to be useful in preventing SNI, but can be difficult to implement. In this study, we examine the results
of using a handheld nerve stimulator for intraoperative sciatic nerve (SN) monitoring during
complex THA requiring limb lengthening and/or significant manipulation of the SN.

Methods: a consecutive series of 11 cases (9 patients, 11 hips) with either severe developmental dysplasia of the hip (Crowe 3-4) or other underlying conditions requiring complex hip reconstruction involving significant leg lengthening and/or nerve manipulation. SN function was monitored intra-operatively by obtaining pre- and post-reduction thresholds during component trialling. The results of nerve stimulation were then used to influence intraoperative decision-making.

Results: No permanent postoperative SN complication occurred, with an average increase of 28.5mm in limb length, range (6-51mm). In 2 out of 11 cases, a change in nerve response was identified after trial reduction, which resulted in an alternate surgical plan (femoral shortening osteotomy and downsizing femoral head). In the remainder cases, the stimulator demonstrated a response consistent with the baseline assessment, assuring that the appropriate lengthening was achieved without SNI. 1 patient had a transient motor and sensory peroneal nerve palsy, which resolved within 2 weeks.

Conclusions: The intraoperative use of a handheld nerve stimulator facilitates surgical decision- making and can potentially prevent SNI. The real-time assessment of nerve function allows immediate corrective action to be taken before nerve injury occurs.