Interleukin‐1‐induced subacromial synovitis and shoulder pain in rotator cuff diseases

Objective. To determine the relationship between the expression of interleukin‐1β (IL‐1β) and IL‐1 receptor antagonists (IL‐1ra) in the subacromial bursa and shoulder pain in rotator cuff diseases. Methods. Synovial specimens were analysed using various methods including reverse transcriptase–polymerase chain reaction (RT–PCR), immunohistochemistry and in situ RT–PCR. Thirty‐nine patients with rotator cuff diseases were candidates. The degree of their shoulder pain was evaluated using a visual analogue scale. Results. The mRNA expression levels of the cytokines were significantly correlated with the degree of pain [IL‐1β: r=0.782; secreted IL‐1ra (sIL‐1ra): r=0.756; intracellular IL‐1ra (icIL‐1ra): r=0.806, P