Short-term outcomes of subacromial injection of combined corticosteroid with low-volume compared to high-volume local anesthetic for rotator cuff impingement syndrome: a randomized controlled non-inferiority trial.

backgroundIn symptomatic tendinosis, a corticosteroid injection into the subacromial space is a palliative treatment option. This study compares high volumes (10 cc) of local anesthetic (LA) combined with triamcinolone acetate (TA) with low volumes (4 cc) of LA combined with TA to see whether the latter would provide similar pain, function and complication outcomes for subacromial injections in patients with impingement syndrome. MATERIALS AND

methodsThis single-center, randomized, single-blind, non-inferiority trial included patients with shoulder pain and positive multiple clinical tests supporting the diagnosis of impingement syndrome. All 52 patients received subacromial injections, with either high-volume corticosteroid injections (HCI) (10 mL total volume of 1% lidocaine plus 40 mg TA) in 26 patients or low-volume corticosteroid injections (LCI) (4 mL total volume of 1% lidocaine plus 40 mg TA) in 26 patients. The demographic data were reported with the primary outcomes being VAS and WORC scores measured at 30 min, then 2 and 8 weeks after receiving the injections. A non-inferiority margin of 13% was assumed.

resultsFifty-two patients (26 patients per group) were enrolled in the HCI and LCI. Mean VAS and WORC scores of HCI and LCI at baseline were 6.96, 33.85, 6.81 and 36.54, respectively. The mean VAS measured at 30 min, 2 and 8 weeks was 4.04, 2.08 and 1.20, respectively, in HCI group and 2.65, 1.95 and 1.26, respectively, in LCI group. The mean WORC at 2 and 8 weeks was 67.46 and 81.74, respectively, in HCI group and 65.42 and 80.12 in LCI group. These were not statistically significantly different (P > 0.05 in all).

conclusionCorticosteroid injections can be used in the treatment of subacromial impingement syndrome. Low-volume (4 cc) corticosteroid injections have non-inferior pain results for VAS score when compared with high-volume (10 cc) corticosteroid injections. CLINICALTRIALS.GOV: NCT03120923. LEVEL OF EVIDENCE: Level I.