Sonoarthrography of the Hip Labrum: Ultrasound Evaluation of the Anterosuperior Acetabular Labrum Following Joint Distension with Magnetic Resonance Arthrographic Correlation

Abstract

Objective: To determine if the anterosuperior labrum can be accurately evaluated by ultrasound after an intra-articular injection, comparing it to same-day magnetic resonance arthrography. Methods:This retrospective study included patients referred for ultrasound-guided hip magnetic resonance arthrogram injections. Following injection, patients received ultrasound evaluation of the anterosuperior labrum. Images were retrospectively reviewed. The labrum was evaluated below the rectus femoris, between the rectus femoris and iliopsoas, and below the iliopsoas. In each location, presence or absence of abnormal morphology, labral clefts, or chondrolabral clefts was recorded. Arthroscopy reports were correlated when available.Results: Twenty six patients received same day injection and magnetic resonance arthrogram. Six patients had arthroscopy. Ultrasound and magnetic resonance arthrogram correlated in 53% of points. When each labrum was divided into three zones, ultrasound demonstrated sensitivity of 0.868 and specificity of 0.160 for labral pathology. Ultrasound showed pathology in all patients below the rectus femoris, and between the rectus femoris and iliopsoas tendons. When limiting evaluation to below the iliopsoas tendon, ultrasound had sensitivity and specificity for labral pathology of 0.650 and 0.667. For labral clefts, ultrasound had sensitivity and specificity of 0.741 and 0.451. For chondrolabral junction clefts, ultrasound reported sensitivity and specificity of 0.578 and 0.303 respectively. For abnormal pathology, ultrasound had sensitivity and specificity of 0.810 and 0.491 respectively. Conclusions:"Sonoarthrography" appears to be a sensitive examination for detecting labral substance tears and abnormal labral morphology. Post-injection ultrasound adds approximately three minutes to the examination and may supply additional useful diagnostic information.