LAUSR

PURPOSE To evaluate the effects of diabetes and corticosteroid injected in the joints on the shoulder motion, gait, and joint capsular properties in a rat stiffness model. METHODS A total of 27 rats were randomly distributed into 3 groups-non-diabetes group (group A), diabetes group (group B), and diabetes plus steroid injection group (group C). The diabetes model was developed by inducing hyperglycemia with a submaximal dose of stroptozotocin, and the stiffness model by completely immobilizing the right shoulder of each animal in all groups with sutures passed between the scapula and humeral shaft. The left shoulder was used as an untreated control in all groups. Three weeks after immobilization, the sutures were removed in all groups, and a single dose of triamcinolone acetonide (0.5mg/kg) was injected into the glenohumeral joint in group C. After 3-weeks of free activity, range of motion (ROM) evaluation, gait analysis by stride length, and capsular area measurement were performed in all rats. RESULTS Hyperglycemia was successfully induced with a mean blood glucose level of 448.9±55.9 mg/dL in group B and 431.6±17.8 mg/dL in group C, which were significantly higher than 136.5±13.4 mg/dL in group A (p<0.001). A significantly smaller ROM and stride length were found in the right (stiffness-induced) shoulder than that in the left (control) shoulder only in group B, and significantly larger capsular area in the right shoulder than that in the left shoulder in groups A and B (all p<0.05). However, in group C, there were no differences between the right and left shoulders in all measurements (all p>0.05). In case of the right shoulders in each group, group C showed significantly larger ROM (68±11° vs. 42±7°) and smaller capsular area (3934.4±537.1 pixel vs. 7402.3±1840.3 pixel) than group B (all p<0.0167). CONCLUSIONS The diabetic model had a detrimental effect on the development of stiffness by thickening the joint capsule, and an intra-articular steroid injection resolved the thickened joint capsule and restored shoulder motion.