MR arthrography of the shoulder: fluoroscopically guided technique using a posterior approach.

433 R arthrography is the preferred imaging technique for the investigation of patients with shoulder instability [1, 2]. MR arthrography reliably shows subtle lesions of the labroligamentous complex, providing information essential to the surgeon concerning the surgery or arthroscopic repair. Most patients presenting with shoulder instability have anterior instability; in these cases, evaluation of the anterior joint structures is required. Contrast material that is inadvertently injected into the extracapsular soft tissues during a conventional anterior approach may cause interpretative difficulties. Intraarticular injection of contrast material using the traditional anterior approach is generally performed under fluoroscopic guidance, although palpation-directed, sonographic, and MR imaging-guided methods have also been described [3–5]. Most of these methods have used an anterior or anterosuperior approach to the shoulder. In our department, we prefer to use a posterior approach for patients with suspected anterior instability. This method is well tolerated by the patient and avoids the interpretative difficulties that may be associated with anterior extracapsular contrast extravasation. A recent study using cadaveric specimens has confirmed that anterior shoulder injection can result in penetration of the anterior stabilizing structures [6]. To our knowledge, there have been no previous clinical studies describing the method, benefits, and safety of the fluoroscopically guided intraarticular injection of contrast material into the glenohumeral joint using a posterior approach, although one report describes using the posterior approach for a sonographically guided method of needle placement [7].