Efficacy of hyaluronic acid or steroid injections for the treatment of a rat model of rotator cuff injury

This study evaluated dorsal root ganglia from C3-C7, analyzed gait, and compared the expression of calcitonin gene-related peptide (CGRP) which was a marker of inflammatory pain in a rat rotator cuff tear model in which the supraspinatus and infraspinatus tendons were detached; comparisons were made to a sham group in which only the tendons were exposed. Fluorogold was injected into the glenohumeral joint 21 days after surgery in both groups, and saline, steroids, or hyaluronic acid was injected into the glenohumeral joint in the rotator cuff tear group 26 days after surgery. The proportions of CGRP-immunoreactive neurons were higher and the gait parameters were impaired in the rotator cuff tear group compared to in the sham group. However, the CGRP expression was reduced and the gait was improved with steroid or hyaluronic acid injection compared to saline, suggesting that both hyaluronic acid and steroid injections suppressed of inflammation which thought to be provided pain relief. While there were no significant differences, the suppression of CGRP expression and the improved gait after hyaluronic acid and steroid injections suggested that both methods were effective for rat rotator cuff tear model. (c) 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1861-1867, 2015.