http://elynsgroup.com Copyright: © 2016 Stone TJ, et al. http://dx.doi.org/10.19104/jorm.2015.108 Open Access Research Article J Orth Rhe Sp Med Journal of Orthopedics, Rheumatology and Sports Medicine Page 1 of 7 ISSN: 2470-9824 Sonoarthrography of the Hip Labrum: Ultrasound Evaluation of the Anterosuperior Acetabular Labrum Following Joint Distension with Magnetic Resonance Arthrographic Correlation Taylor J. Stone 1 *, Niamh Long 2 , Catherine N. Petchprapa 2 , Ronald S. Adler 2 1 Charlotte Radiology, Charlotte, NC, USA 2 New York University Langone Medical Center & Hospital for Joint Diseases, New York, NY, USA 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. Keywords: Ultrasound; Sonoarthrography; Magnetic Resonance Arthrography; Acetabular Labrum; Labral Tears Introduction Acetabular labral tears are thought to be a common cause of hip pain, with reported prevalence of labral tears in patients with hip or groin pain ranging from 22-55% [1-6]. The diagnosis of labral tear may be clinically challenging, and the differential diagnosis is broad, including contusion, strain, athletic pubalgia, osteitis pubis, inflammatory arthritis, osteoarthritis, septic arthritis, piriformis syndrome, snapping hip syndrome, bursitis, osteonecrosis, fracture, dislocation, tumor, hernia, or referred pain [5,7]. Ultrasound-guided diagnostic anesthetic or therapeutic anesthetic and steroid hip injections are commonly ordered for patients with hip pain, in whom intra-articular pathology is suspected. The rationale is that relief of symptoms after injection of anesthetic confirms an intra-articular pain generator, which includes labral pathology among other etiologies [8]. Studies have demonstrated that fluoroscopic-guided diagnostic hip injections are 88% sensitive and 100% specific for detecting an intra-articular etiology of hip pain [9,10]. For various reasons, a diagnosis of labral tear may have not been established at the time an ultrasound-guided hip injection is performed. Preprocedural imaging is often not available, having not been performed or performed at another institution, and cartilage loss or labral pathology has not been confirmed. Furthermore, magnetic resonance imaging (MRI) and magnetic resonance arthrography (MRA) examinations, while the best imaging tests available, are not always definitive. At our institution, direct MRA is frequently performed following ultrasound-guided intra-articular injection of a dilute gadolinium mixture. Intra-articular contrast injection distends the joint capsule in a similar manner to therapeutic hip injection, and the greater volume (10-15 cc) used for arthrography has the potential to provide greater joint distention than the smaller volume used for a diagnostic/therapeutic injection. Sonographic interrogation of the anterosuperior acetabular labrum following ultrasound- guided gadolinium contrast injection provided an opportunity for same day correlation of findings with MRA. Therefore, our aim is to see if the anterosuperior labrum and chondrolabral junction could be evaluated by ultrasound after an intra-articular injection (“sonoarthrography”) to detect and confirm labral pathology and compare it to same-day MRA as a reference standard, and arthroscopy when available. Materials and Methods Patient Selection and Data This retrospective study was approved by the local Institutional Review Board and complied with local ethical standards. All patients were referred from local orthopedic surgery or sports medicine practices to our radiology department for an ultrasound- guided injection of intra-articular dilute gadolinium contrast for MRA examination. Standard practice including informed consent was followed. Patient’s age, gender, sidedness of study, and body mass index (BMI) were recorded. Inclusion and Exclusion Criteria Patients between the ages of 18-65 referred to the department of radiology for ultrasound-guided hip MRA injection between October 2013 and August 2014 were included in our study. Patients were excluded if they had prior labral surgery or were contraindicated for MRI or gadolinium administration. Ultrasound-Guided Intra-Articular Injection Intra-articular injection was performed according to standard Received Date: January 06, 2016, Accepted Date: January 19, 2016, Published Date: January 28, 2016. *Corresponding author: Taylor J. Stone, Charlotte Radiology, 1701 East Blvd, Charlotte, NC 28203-5896, Tel: 704-334-7800; Fax: 704-334-7818; E-mail: Taylor.stone@charlotteradiology.com