723 was first described in 1933 by Oberholzer [21] and enced musculoskeletal radiologist, fluoroscopic-guided ante- modified by Schneider [22]. Other methods for intra- rior (FLa), fluoroscopic-guided posterior (FLp), US-guided articular injection of the glenohumeral joint have been anterior (USa) and US-guided posterior (USp). described, e.g., fluoroscopically guided using a posterior All patients underwent intra-articular injection of approach [9, 10], palpation directed [4, 19], ultrasound gadoterate meglumine (gadoteric acid) 0.0025 mmol/ml (US) [2, 3, 14], CT [11] and MR guided [7, 20]. These (Artirem®; Guerbet S.A., Villepinte, France), which is a studies deal mostly with the techniques and/or their dilution (1:200) of Dotarem® (Gd-DOTA) provided in pre- feasibility. Nowadays there is growing interest in evaluat- filled syringes of 20 ml, until intra-articular pressure rose or ing and improving radiologists’ interpretive performance up to a maximum of 20 ml. and efficiency in delivering patient care. However, little is known about differences in accuracy of contrast injection, the effect of contrast leakage on image interpretation [19], Injection techniques the time taken and the discomfort experienced by the patient [23, 24] among different radiologists using All radiologists used the technique and materials with different techniques. which they were familiar. The FLp and Fla injections were The purpose of our study was to prospectively assess the performed with a 1.2 mm × 88.9-mm spinal needle (18- variation in accuracy, effect of leakage of contrast medium gauge, 3.5 inch) and a 0.9 × 90-mm spinal needle (20 on diagnostic quality, the time required and the discomfort gauge), respectively, and the US-guided injections with a experienced by the patient for the introduction of contrast 0.8 × 50-mm bevelled needle (21-gauge) without a stylet. material into the glenohumeral joint with four different The Fla injections are performed with the patient supine in frequently applied image-guided (fluoroscopy and US) a straight anteroposterior position with the shoulder slightly injection techniques. externally rotated. The needle is directed vertically under fluoroscopic control at the junction of the middle and lower thirds of the medial part of the humeral head (Figs. 1 and 3). Materials and methods See also Figs. 2 and 3. The Flp injections are performed in prone position with Patients the symptomatic shoulder slightly raised until the gleno- humeral joint is seen tangentially [9, 10]. The injection site A prospective study was performed in four centres each is infiltrated with local anaesthetic [prilocaïnehydrochlor- including 25 consecutive patients with shoulder instability ide 10 mg/ml (Citanest® 1%), Astra Pharmaceutica, who were referred for MR arthrography by orthopaedic Zoetermeer, The Netherlands] using a 0.8 × 50-mm bev- surgeons. Patient characteristics are illustrated in Table 1. elled needle (21 gauge). With the shoulder in a neutral Patients who had previously undergone shoulder surgery position or slightly internally rotated, the needle is aimed at were excluded. Institutional review board approval and the inferomedial quadrant of the humeral head and verbal consent were obtained. advanced vertically under fluoroscopic guidance to the Four radiologists in four different centres were deliberately cartilage of the humeral head (Figs. 2 and 4) [9, 10]. chosen because each routinely used a different approach for The USa approach was performed according to Valls [3]. glenohumeral injection. In this way we were able to audit and Patients are supine with the shoulder slightly externally compare the daily practice of various glenohumeral humeral rotated. A HDI 5000 SonoCT (ATL/Philips, Best, The injection techniques applied by experienced musculoskeletal Netherlands) with a 5–8-MHz curved array transducer was radiologists (>9 years of experience each). In each centre a used to visualise the needle (Fig. 5A). After skin and different intra-articular approach was applied by an experi- transducer preparation with alcohol 70%, the patient’s Table 1 Four patient groups FLa FLp USa USp Patients No. 25 25 25 25 Gender M 17 14 16 19 F 7 11 9 6 Age Mean/median (range) 39/44 (14–69) 44/44 (28–62) 35/34 (18–59) 36/37 (16–69) Sidedness L 9 14 9 10 R 16 11 16 15 Number of patients per group, gender, age and sidedness of the punctured shoulders are displayed USa: US-guided anterior injection, USp: US-guided posterior injection, FLa: fluoroscopic-guided anterior injection, FLp: fluoroscopic- guided posterior injection