Accuracy of palpation-directed intra-articular glenohumeral injection confirmed by magnetic resonance arthrography.

PURPOSE: The aim of this study was to determine the accuracy of anatomic palpation-directed injections in the office setting. METHODS: Two hundred twenty-six shoulders in 208 patients were studied using a 0.2-Tesla extremity scanner after the injection of gadolinium-diethylene triamine pentaacetic acid-saline. All patients were injected in a sterile fashion by a single board-certified shoulder surgeon using an anterior approach by palpating the rotator interval anterior to the acromioclavicular joint and angling the needle 45° lateral and 45° caudad. All injections, successful or otherwise, were single injections. Magnetic resonance (MR) arthrograms were retrospectively read by 2 musculoskeletal fellowship-trained, board certified radiologists to determine whether the injection was in the glenohumeral joint. RESULTS: Two hundred one of the 226 injections were successful (88.9%). Of the 25 unsuccessful injections, the contrast material extravasated out of the capsule in 5 cases and into the subscapularis tendon in 10 cases. The contrast material was injected into the subacromial space in 9 cases, into the rotator interval fat in 9 cases, and into extracapsular tissue in 6 cases. There was insufficient volume of contrast material in 10 cases. The accuracy rate was 88.9%. There were no complications. CONCLUSIONS: The palpation-directed rotator interval anterior approach technique for intra-articular glenohumeral MR arthrogram injections performed by a single surgeon was 88.9% accurate. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Analysis of Low-Field MRI Scanners for Evaluation of Shoulder Pathology Based on Arthroscopy.

BACKGROUND: Many studies have compared the diagnostic capabilities of low-field magnetic resonance imaging (MRI) scanners to high-field MRI scanners; however, few have evaluated the low-field MRI diagnoses compared with intraoperative findings. PURPOSE: To determine the accuracy and sensitivity of low-field MRI scanners in diagnosing lesions of the rotator cuff and glenoid labrum. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 3. METHODS: Over a 2-year period, MRI examinations without intra-articular contrast were performed on 79 patients for shoulder pathologies using an in-office 0.2-T extremity scanner. The MRI examinations were read by board-certified, musculoskeletal fellowship-trained radiologists. All patients underwent shoulder arthroscopy performed by a single sports fellowship-trained orthopaedic surgeon within a mean time of 56 days (range, 8-188 days) after the MRI examination. The mean patient age was 54 years (range, 18-81 years). Operative notes from the shoulder arthroscopies were then retrospectively reviewed by a single blinded observer, and the intraoperative findings were compared with the MRI reports. RESULTS: For partial-thickness rotator cuff tears, the sensitivity, specificity, positive predictive value, and negative predictive value were 85%, 89%, 79%, and 92%, respectively. For full-thickness rotator cuff tears, the respective values were 97%, 100%, 100%, and 98%. For anterior labral lesions, the values were 86%, 99%, 86%, and 99%, and for superior labral anterior-posterior (SLAP) lesions, the values were 20%, 100%, 100%, and 79%, respectively. CONCLUSION: Low-field MRI is an accurate tool for evaluation of partial- and full-thickness rotator cuff tears; however, it is not effective in diagnosing SLAP lesions. More information is needed to properly assess its ability to diagnose anterior and posterior labral lesions.