Type:
Educational Exhibit
Keywords:
Not applicable, Education and training, Arthrography, MR, Fluoroscopy, Musculoskeletal joint, Anatomy, Musculoskeletal
Authors:
P. kelly, C. ODonnell, G. Rahmani, S. Davey; galway/IE
DOI:
10.26044/ecr2020/C-10109
Findings and procedure details
Direct MR Arthrography of the shoulder is performed under aseptic conditions in the fluoroscopy suite at our institution. The procedure is explained to the patient and written consent is obtained. The procedure is considered extremely safe however consent in obtained for potential complications including pain, infection, bleeding, chemical synovitis and contrast reactions. The MRI checklist is then completed. The approach under fluoroscopic guidance is either anterior or posterior. The rotator interval approach yields less artefacts. We use a 21G spinal needle with the shoulder held in external rotation to access the joint space. A point is chosen on the humeral head that curves away from the needle to allow more room for the bevel. The approach is typically through the rotator interval slightly medial to the biceps tendon, the midjoint or inferomedial aspect of the humeral head. Confirmation within the glenohumeral space is confirmed with 2-3ml of Omnipaque 300 using intermittent fluoroscopy. The joint capsule can be quite firm and may be mistaken for bone. It is important to be lateral to the glenoid labrum when injecting as direct injection may mimic a tear. We then use a dilute concentration of gadolinium 1:200 (Magnevist) to gently distend the joint capsule. The patient is then transported to the MRI department. We use T1, T2 FS and proton density sequences.
Common Pathological Findings:
- The Buford complex consists of an absent anterosuperior labrum with a thickened middle glenohumeral ligament.
- The ALPSA lesion refers to a torn anteroinferior labrum which is medially displaced and attached to the scapula only by a sleeve of periosteum.
- Bankart lesion results from a tear of the anteroinferior labrum from 3 to 6 o'clock after an anterioinferior humeral head dislocation. It can be associated with a bone fracture which results in the Bankart lesion and a Hill Sachs lesion.
- Posterior labral tears often result in a reverse Bankart lesion where a tear of the labrum and underlying periosteum can result in detachment. This is classically seen in posterior dislocation.
- Intraarticular loose bodies are either primary(uncommon) or secondary (common). The primary form cause is unknown whearas the secondary form is associated with osteoarthritis, osteonecrosis, osteochondritis dissecans, neuropathic osteoarthropathy, trauma and rheumatoid arthritis.
- Tears of the rotator cuff muscles and tendinous insertion including supraspinatus, infraspinatus, subscapularis and teres minor. 3 Tesla MRI appears equivalent to arthrography in the diagnosis of rotator cuff tears.
- Hill Sachs lesions are compression fractures of the posterolateral humeral head associated with recurrent anterior shoulder dislocation. There may be an associated Bankhart lesion.