Shoulder pain and intra-articular interleukin-8 levels in patients with rotator cuff tears.

Aim: Rotator cuff disease (RCD) is one of the most common disorders in the shoulder joint and causes joint pain and functional disability. In this study, we investigated the associations among cytokine levels and clinical symptoms in patients with RCD.

Method: Joint fluid specimens of the shoulder joint were obtained from 38 patients with RCD before arthroscopic surgery. The levels of inflammatory cytokines, including interleukin (IL)-1β, IL-6 and IL-8, were evaluated using enzyme-linked immunosorbent assay kits, and the associations between these cytokine levels and the clinical symptoms were determined. A multiple linear regression analysis was performed to identify the parameters accounting for the visual analogue scale (VAS) score at rest.

Results: IL-8 level was correlated with IL-6 (r = 0.434, P = 0.006) and IL-1β (r = 0.575, P < 0.001) levels. The cuff tear size was inversely correlated with the VAS score at rest. A multiple stepwise linear regression analysis revealed that the VAS score at rest could be explained by the VAS score at night, the VAS score during movement and the intra-articular IL-8 level (adjusted R² = 0.544, P < 0.001). The intra-articular IL-8 level is associated with resting pain in rotator cuff tear patients.

Conclusion: These results suggest that an increased concentration of IL-8 is associated with resting pain in rotator cuff tear patients.