728 Pre-procedure Min–max (mean) FLa 0 – 90 (30) FLp 3 – 100 (42) USa 0 – 75 (27) USp 0 – 80 (38) Table 4 VAS pain score for US- and fluoroscopy-guided glenohumeral injections Post-procedure Min–max (mean) 0 – 100 (39) 0 – 100 (28) 0 – 70 (16) 0 – 80 (27) VAS difference Mean +9 −14 −11 −11 Decrease No. of patients 3 (12%) 15 (60%) 13 (52%) 13 (52%) Increase No. of patients 15 (60%) 4 (16%) 4 (16%) 5 (20%) Equal No. of patients 7 (28%) 6 (24%) 8 (32%) 7 (28%) USa: US-guided anterior injection, USp: US-guided posterior injection, FLa: fluoroscopic-guided anterior injection, FLp: fluoroscopic- guided posterior injection, VAS-difference: VAS score post-procedure - VAS score pre-procedure patients to indicate that the procedure was less painful than they had expected. In 44 patients the VAS score decreased following injection, whereas in 28 patients it increased, and in 28 patients the VAS score measured pre- and post- procedure remained equal. The mean VAS score of the FLp, USa and USp injections decreased 14, 11 and 11 points following injection, respectively, while it increased with 9 points in the FLa group (Kruskal-Wallis p = 0.001). In fact, the post-procedure VAS score of the FLa procedure increased in 60% of the patients. There was a higher average pain score after FLa injection as compared to FLp. Patients who underwent US-guided procedures reported less pain than those who underwent the fluoroscopic- guided procedures. The USa approach was rated with the lowest pre- and post-injection VAS scores. Discussion The main advantage of image-guided glenohumeral joint injection over blind injection is that the needle position can be confirmed and injection of contrast medium can be controlled. This is especially advantageous in teaching hospitals (when training residents) and when the number of MR arthrographies are limited. The current study describes four different image-guided approaches. Intra-articular deposition of contrast material was successful in all patients, which is comparable with reported results in the literature [2, 3, 10, 13]. The success rate of the first attempt with US guidance (97%) was significantly better compared to fluoroscopic guidance (72%). In the literature the accuracy of “blind” glenohumeral injections varies from 26-100% [15–19]. Catalano et al. [19]] showed that with a palpation-directed posterior approach, the glenohumeral joint could be entered successfully on respectively the first, second and third attempt in 85%, 13% and 2% of the cases [19]. In this study the US procedure was less time consuming than the fluoroscopic-guided procedure (2.30 min versus 7 min, i.e., only 36% of the time needed with fluoroscopic guidance). This may be due to the received pre-procedural local anaesthetics and the injection with iodinated contrast to confirm the intra-articular position. The reported time of blind injection by Catalano was 3 min [19]. The occupancy of the US room is only 52% of the fluoroscopy room (Table 3). The figures of leakages are summarised in Table 2. The number is high compared to those reported by Catalano et al. [19]. This may be due to strict criteria. Every small amount of contrast material along the needle tract was graded minimal leakage. The frequent leakage did not cause interpretative difficulties. All patients were clinically sus- pected of having anterior labral problems, and therefore posterior leakage did not hamper interpretation. Contrast material anteriorly did not compromise diagnostic quality, because the contrast medium was usually depicted in close relationship to the needle tract. In six cases massive leakage was obviously due to capsular disruption (n=3), pathology of the labrum (n=2) and a full-thickness rotator cuff tear (n=1). Patients who undergo arthrography in general experi- ence less pain than expected [23]. In our study 44% of the patients considered discomfort less than expected and 28% more than expected. However, in the subgroup of patients who underwent the FLa approach (Table 4), 60% experienced more discomfort than expected. This can be explained by the fact that no local anaesthetics and a thicker needle (20 gauge) were used and the fact that manipulation of the stylet and syringe causes unintended movements of the needle. In this study four minor complications, e.g., vasovagal reactions, were reported, which resolved without medical intervention: two in the USp group and two in the FLa group. Other minor complications included pain, urticaria and headaches [25]. All four procedures were difficult due to adipositas (n = 3) and postoperative status (n = 1). Hugo [25] showed in a multi-institutional survey a total compli- cation rate of 3.6%. Serious complications account for 0.02% and consist mainly of infections and rarely of anaphylaxis and vascular complications [25]. In our study there were no advantages comparing the anterior approach with the posterior approach. Some authors [2, 9, 10, 14, 19] advocate the posterior approach, because most pathologies of the stabilising structures of the