Comparison of efficacy of Oral versus Intra-articular Corticosteroid Application in the treatment of Frozen Shoulder: An experimental study in rats

The aim of this study was to compare clinical and histopathological effects of oral versus intraarticular corticosteroid application in a rat model of frozen shoulder.In this study, eighty adult Sprague-Dawley rats were used. The animals were divided into 5 equal groups. The frozen shoulder model was created by immobilizing animals' shoulders with internal fixation with sutures for 8 weeks. At the 8th week, sham (n: 16) and control (n: 16) groups were sacrificed to collect data for healthy and affected shoulders. Also, at the 8th week, 50 mg/ kg methylprednisolone was started for the oral treatment group, and a single dose of 0.5 mg/kg triamcinolone acetonide was injected for the intraarticular treatment group. The effect of additional steroid treatment was expected for 2 weeks, then all remaining treatment and natural course groups were sacrificed on the 10th week.After sacrification, specimens taken as "en bloc" scapulothoracic disarticulation were randomly divided into two groups for a range of motion measurement and histopathological examination. The control (frozen shoulder model) group's shoulder range of motion in all directions was lower than the sham (healthy) group (P < 0.01). Natural course and intraarticular steroid groups, compared to the frozen shoulder model showed a significant increase in the direction of abduction (P < 0.05). Also, it was found for treatment groups that in all directions the range of motion was not as good as the healthy values (P < 0.01). The intraarticular treatment group showed higher degrees of abduction compared to the natural course and oral steroid treatment groups (P < 0.01). Oral steroid treatment group's range of motion was not significantly better than the disease model and had no superiority to the natural course group (P > 0.05). Histopathologically, no statistically significant difference was observed between the groups for signs of frozen shoulder which was found in the immobilized group (P > 0.05). Histopathologically, immobilization was found to cause thickening of the capsule that cannot be resolved by treatment. (P < 0.05).In frozen shoulder disease, intraarticular steroid injection seems to be superior in increasing the range of motion than oral steroid treatment.