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Ultrasonography‐guided contrast media injection to shoulder joint using a posterior approach: a technique worth trying

In magnetic resonance (MR) studies of the shoulder joint, intra-articular fluid outlines anatomic details and subtle tears. MR arthrography can provide good information in experienced hands. Intra-articular access can be cumbersome, however, due to inexperience and to traumatic or postoperative anterior capsular or labral changes (4). Anteriorly performed injection of the MR contrast media can be started like traditional fluoroscopic arthrography but with the addition of 10 ml diluted gadolinium. This procedure is known to be guided by ultrasonography (US), sometimes by computed tomography (CT) or MR, but also by mere palpation. Some colleagues rely on the feel of the needle slipping into the joint slit or on seeing it bending there under X-ray control (1). It has recently been proposed to inject towards the upper part of caput humeri into the rotator cuff interval (2). In some clinics, the iodinated contrast media has been injected posteriorly under fluoroscopic control as a matter of routine, with 100% results (3). Arthroscope and medications are commonly inserted posteriorly without any image guidance at all. The anatomy at the middle level of the posterior glenohumeral joint slit is depicted here by transaxial ultrasonic and MR arthrographic images (Figs. 1 and 2). The posterior glenoid labrum has been seen by ultrasound in healthy volunteers according to a small survey (5). In my experience, the free edge of the posterior glenoid labrum could be identified in all patients of 20 serial shoulder US examinations when the reflecting surfaces were dynamically augmented by small to-and-fro rotations of the humerus; a lower frequency probe was used in thick shoulders. The anterior labrum lies deeper and more vertically, and because of traumatic changes it does not always stand out as might be expected. As ultrasonic equipment is widely available, the posterior injection technique is a simple and patient friendly procedure worth trying. In the sitting position, palm resting on the ipsilateral thigh, the posterior joint capsule is fairly slack. The posterior labrum is first scanned dynamically by US and the lateral edge preferably marked to the skin. The anesthetic needle is then inserted just lateral to the labrum edge through the infraspinatus muscle and the joint capsule straight on to the caput cartilage and kept there. The anesthetic should now be felt to spread underneath the capsule without significant resistance and 10 ml diluted gadolinium (or saline) subsequently as well. The intra-articular spread of the thin contrast media line is not readily discerned at first, but it can be checked at the end by another US view or finally by the subsequent MR images. Moreover, extra-articular posterior injection is unlikely to interfere with MR images anteriorly.