Rat models of frozen shoulder: Classification and evaluation

Frozen shoulder (FS), also known as adhesive capsulitis, is a condition that causes contraction and stiffness of the shoulder joint capsule. The main symptoms are persistent shoulder pain and a limited range of motion in all directions. These symptoms and poor prognosis affect people's physical health and quality of life. Currently, the specific mechanisms of FS remain unclear, and there is variability in treatment methods and their efficacy. Additionally, the early symptoms of FS are difficult to distinguish from those of other shoulder diseases, complicating early diagnosis and treatment. Therefore, it is necessary to develop and utilize animal models to understand the pathogenesis of FS and to explore treatment strategies, providing insights into the prevention and treatment of human FS. This paper reviews the rat models available for FS research, including external immobilization models, surgical internal immobilization models, injection modeling models, and endocrine modeling models. It introduces the basic procedures for these models and compares and analyzes the advantages, disadvantages, and applicability of each modeling method. Finally, our paper summarizes the common methods for evaluating FS rat models.