Intraoperative Neurophysiological Monitoring in Total Hip Arthroplasty for Crowe Types 3 and 4 Hips

Area of Science:

• Orthopedic Surgery
• Neurophysiology
• Biomedical Engineering

Background:

• Crowe types 3 and 4 hip dysplasia often require total hip arthroplasty (THA) with femoral shortening osteotomy (FSO).
• Peripheral nerve palsy is a known complication of THA, occurring in 0.08% to 3.7% of cases.
• Nerve damage can result from direct trauma or excessive limb extension during surgery.

Purpose of the Study:

• To evaluate the effectiveness of intraoperative neurophysiological monitoring (IONM) in THA for Crowe types 3 and 4 hips.
• To assess the incidence of nerve palsy following THA with IONM in this patient population.
• To determine the impact of IONM on the utilization of femoral shortening osteotomy (FSO).

Main Methods:

• Retrospective review of patients undergoing primary THA with IONM.
• Inclusion criteria: Crowe types 3 and 4 dysplastic hips.
• Intraoperative assessment of motor-evoked potentials and somatosensory-evoked potentials; measurement of dislocation height and trochanteric differences.

Main Results:

• Twenty-three hips in 19 patients (mean age 45) were analyzed; 43% Crowe type 4, 57% Crowe type 3.
• Postoperative limb length discrepancy was minimal (mean 8.5 mm in 6 patients).
• No instances of motor or sensory nerve dysfunction were reported postoperatively.

Conclusions:

• IONM is a safe and effective tool for THA in severe hip dysplasia, preventing nerve palsy.
• IONM facilitated THA without nerve complications in all cases.
• The use of subtrochanteric FSO was significantly reduced, particularly in Crowe type 4 hips, when IONM was employed.