[Imaging of posttraumatic shoulder instability : Current concepts]. / Bildgebung bei posttraumatischen Instabilitäten der Schulter : Aktuelle Konzepte.

Posttraumatic instability accounts for more than 95% of all shoulder instabilities with the highest incidence in patients between 20 and 30 years of age. In this age group, lesions of the capsulolabral complex are the most common sequelae after the first shoulder dislocation. Typical acute findings are the Bankart and Perthes lesions and humeral avulsion of the glenohumeral ligament (HAGL). Chronic sequelae are anterior labroligamentous periosteal sleeve avulsion (ALPSA) lesions, and nonclassifiable lesions with deficient anterioinferior labrum and glenohumeral ligaments. Recently, quantification of Hill-Sachs and bony Bankart lesions with glenoid defects have become the focus of interest: bipolar bone loss has emerged to be one important factor of recurrent instability that has not been addressed during the first stabilizing operation. The glenoid track concept emphasizes the importance of bipolar bone loss, where the glenoid track refers to the contact area between the humeral head and the glenoid at the end-range of motion in abduction, extension and external rotation. Any lesion of the humeral head that extends beyond the glenoid track is considered high risk for engagement of the humeral head at the glenoid margin with subsequent dislocation. Both the Hill-Sachs interval and the glenoid track can be determined using computed tomography (CT) and magnetic resonance imaging and, thus, help to define the status of the shoulder (on-track vs. off-track), which is prerequisite for planning the appropriate operative procedure. Similar tendencies also exist for posttraumatic posterior instabilities which are much rarer.

ABER Position in Direct MR Arthrography of the Shoulder: Useful Adjunct or Waste of Imaging Time? / Die ABER-Position bei der direkten MR-Arthrografie der Schulter: Sinnvolle Ergänzung oder Verschwendung von Messzeit?

PURPOSE: The usefulness of direct MR arthrography of the shoulder with additional ABER position (ABER-MRA) has always been discussed. The goals of the following review are to analyze the usefulness of this technique according to the available literature and present recommendations with respect to indications and benefits in diagnostic imaging of shoulder abnormalities in the clinical routine. METHOD: For this review we assessed the current literature databases of the Cochrane Library, Embase, and PubMed with regard to MRA in the ABER position up to the February 28, 2022. Search terms were "shoulder MRA, ABER", "MRI ABER", "MR ABER", "shoulder, abduction external rotation MRA", "abduction external rotation MRI" and "ABER position". The inclusion criteria were prospective and retrospective studies with surgical and/or arthroscopic correlation within 12 months. Overall, 16 studies with 724 patients fulfilled the inclusion criteria: 10 studies dealing with anterior instabilities, three studies with posterior instabilities and seven studies with suspected rotator cuff pathologies (some studies addressing multiple items). RESULTS: For anterior instability the use of ABER-MRA in the ABER position led to a significant increase in sensitivity for detecting lesions of the labral ligamentous complex compared with standard 3-plane shoulder MRA (81 % versus 92 %, p = 0.001) while maintaining high specificity (96 %). ABER-MRA demonstrated high sensitivity and specificity (89 % and 100 %, respectively) for SLAP lesions and was able to detect micro-instability in overhead athletes, but case counts are still very small. With regard to rotator cuff tears, no improvement of sensitivity or specificity could be shown with use of ABER-MRA. CONCLUSION: Based on the currently available literature, ABER-MRA achieves a level of evidence C in the detection of pathologies of the anteroinferior labroligamentous complex. With regard to the evaluation of SLAP lesions and the exact determination of the degree of rotator cuff injury, ABER-MRA can be of additive value, but is still a case-by-case decision. KEY POINTS: · ABER-MRA is useful in the evaluation of pathologies of the anteroinferior labroligamentous complex. · ABER-MRA does not increase sensitivity or specificity with regard to rotator cuff tears. · ABER-MRA may be helpful for the detection of SLAP lesions and micro-instability in overhead athletes. CITATION FORMAT: · Altmann S, Jungmann F, Emrich T et al. ABER Position in Direct MR Arthrography of the Shoulder: Useful Adjunct or Waste of Imaging Time?. Fortschr Röntgenstr 2023; 195: 586 - 595.