Rilonacept in the treatment of subacromial bursitis: A randomized, non-inferiority, unblinded study versus triamcinolone acetonide.

Introduction: Subacromial bursitis is caused by inflammation of the bursa that separates the superior surface of the supraspinatus tendon from the overlying coraco-acromial ligament and acromion. While multiple cytokines are implicated, interleukin-1 beta appears to play a prominent role. Rilonacept, an interleukin-1 trap, may be an alternative to corticosteroid injection for the management of this condition.

Methods: This single center, randomized, non-inferiority, unblinded study recruited 33 subjects over 9 months. Twenty subjects received 160mg intrabursal injection of rilonacept and 13 received a 6mL mixture of lidocaine, bupivacaine, and 80mg triamcinolone acetonide. QuickDASH, subject reported pain, and adverse events were recorded at time of injection, 2 days later, 2 weeks later, and 4 weeks later. Primary outcome was improvement in QuickDASH 4 weeks post-injection. Secondary outcomes were improvement in subject reported pain and occurrence of adverse events at 4 weeks.

Results: Both study groups were equally matched for age, gender, ethnicity, and site of bursa injection. Both medications demonstrated a statistically significant improvement in QuickDASH 4 weeks post-injection, but triamcinolone acetonide injection offered greater improvement (P=0.004). Both medications demonstrated improvement in subject reported pain but between group comparison at 4 weeks showed that triamcinolone was superior (P=0.044). No statistically significant differences in adverse events were noted between groups, but subjects who received rilonacept experienced more episodes of diarrhea and headache.

Conclusions: While improvement in QuickDASH and pain was noted with a single intrabursal injection of rilonacept at 4 weeks, injection with triamcinolone acetonide was more efficacious. This trial was registered with www.clinicaltrials.gov (NCT01830699).