726 Netherlands). Confirmation with real time US can be performed without the use of iodinated contrast media by visualising the intra-articular flow of fluid during injection or by visualising the intra-articularly injected fluid underneath the capsule and/or labrum posteriorly and underneath the subscapular tendon anteriorly, or around the long head of the biceps tendon. The amount of injected contrast material was recorded. MR imaging was performed within 15 min of the injection with a 1.0-T or a 1.5-T MR system. In all centres a dedicated receive-only shoulder coil was used. Images were used for diagnostic purpose and to assess retrospectively the intra- articular position and contrast leakage by an independent blinded radiologist who did not perform the procedure. Leakage was graded using a five-grade scale (Table 2). Visual analogue scale Before and after injection, patients graded their anticipated and experienced level of pain. A visual analogue scale (VAS) was used, with a scale from 0 (“no pain”) to 100 (“unbearable pain”). Complications were recorded. Statistical analysis For descriptive purposes, mean and standard deviations are reported for room time, radiologist time, total procedure time and VAS scores. Because the variables were non-normally distributed, nonparametric Kruskal- Wallis tests were used to test for statistical differences. Statistical significance was accepted if the P value was less than 0.05. The comparisons between the techniques were not adjusted for the patients’ sex, age or right or left shoulder. The distribution of all categorical variables was presented in frequencies. Differences in these distributions were tested for statistical significance using chi-square tests. All statistical analyses were performed using SPSS, version 14.0.2 for Windows (Chicago, IL) by an experienced statistician (L.K.). Results Patient groups As illustrated in Table 1, the patient groups involved in this study were quite similar in sex, age distribution and sidedness of the affected shoulder. There was a slight predominance in right shoulders, as one might expect, as most people are right-handed. Patients’ gender and left or right shoulder were not significantly related to room time, radiologist time, total procedure time and difference between the pre- and post-procedure VAS scores. The age of the patients was only weakly (r2< 0.04) correlated with the three time variables and not at all correlated with the VAS score difference. Therefore, the analyses were not adjusted for age, sex and laterality. Table 2 Accuracy, number of attempts to gain access to the glenohumeral joint, injected volume and leakage of contrast media with four different image-guided approaches Number of patients (N) Intra-articular injection 1st attempt 2nd attempt 3rd attempt No leakage Minimal leakage noncompromising Massive leakage noncompromising Minimal leakage compromising Massive leakage compromising Minimal injected volume (ml) Maximal injected volume (ml) Mean injected volume (ml) Local anaesthetics Needle size (gauge) Overall 100 100 (100%) 83 (83%) 14 (14%) 3 (3%) 49 (49%) 24 (24%) 27 (27%) 0 (0%) 0 (0%) 5.0 20.0 15.6 – – FLa 25 25 (100%) 19 (76%) 5 (20%) 1 (4%) 8 (32%) 12 (48%) 5 (20%) 0 (0%) 0 (0%) 10.0 20.0 14.5 No 20 FLp 25 25 (100%) 17 (68%) 6 (24%) 2 (8%) 13 (52%) 3 (12%) 9 (36%) 0 (0%) 0 (0%) 9.0 20.0 14.9 Yes 18 USa 25 25 (100%) 24 (96%) 1 (4%) 0 (0%) 16 (64%) 4 (16%) 5 (20%) 0 (0%) 0 (0%) 5.0 20.0 14.6 No 21 USp 25 25 (100%) 23 (92%) 2 (8%) 0 (%) 12 (48%) 5 (20%) 8 (32%) 0 (0%) 0 (0%) 10.0 20.0 18.6 No 21 FL(a + p) 50 50 (100%) 36 (72%) 11 (22%) 3 (6%) 21 (42%) 15 (30%) 14 (28%) 0 (0%) 0 (0%) 9.0 20.0 14.7 – – US(a + p) 50 50 (100%) 47 (94%) 3 (6%) 0 (0%) 28 (56%) 9 (18%) 13 (26%) 0 (0%) 0 (0%) 5.0 20.0 16.6 – – USa: US-guided anterior injection, USp: US-guided posterior injection, FLa: fluoroscopic-guided anterior injection, FLp: fluoroscopic- guided posterior injection, FL (a + p): fluoroscopic-guided anterior and posterior approach, US (a + p): US-guided anterior and posterior approach