# Role of Intraoperative Nerve Monitoring in Preventing Peripheral Nerve Injury During Total Hip Arthroplasty in High-Risk Patients

## TL;DR

This study shows that using intraoperative nerve monitoring during hip replacement surgery helps prevent nerve injuries, especially in high-risk patients.

## Contribution

The study demonstrates the effectiveness of regular interval nerve monitoring in preventing nerve injury during total hip arthroplasty in high-risk patients.

## Key findings

- IONM detected MEP changes in 6.3% of cases during THA.
- Regular interval monitoring prevented postoperative muscle weakness in most cases.
- One case showed irreversible nerve damage due to delayed detection.

## Abstract

Background

Intraoperative nerve monitoring (IONM) plays a crucial role in preventing peripheral nerve injury during total hip arthroplasty (THA). However, its efficacy in THA remains controversial. This study aimed to evaluate the efficacy of IONM in preventing peripheral nerve injury during THA.

Methods

This study retrospectively included 79 hips in 72 patients (primary THA: 43 hips; revision THA: 36 hips) with risk factors for intraoperative nerve injury who underwent motor evoked potential (MEP) monitoring combined with THA between July 2011 and March 2019. A concerning MEP change was defined as a decrease to <30%. The frequency and cause of the MEP change and the presence of postoperative neurological symptoms were investigated.

Results

Motor evoked potential changes were detected in five of the 79 hips (6.3%). In one of these cases, the potential amplitude did not recover, and transient postoperative muscle weakness was observed due to the delayed detection of MEP changes. In the remaining cases, the potential change was quickly detected by IONM, including the regular-interval monitoring method, without any subsequent postoperative muscle weakness.

Conclusions

Intraoperative nerve monitoring effectively prevented peripheral nerve injury during THA, particularly in patients with developmental dysplasia of the hip (DDH) or a history of hip surgery. To prevent irreversible postoperative neuropathy, regular interval nerve monitoring, and free-run electromyography should be considered routine techniques in THA for patients with DDH or a history of hip surgery.