Morphology of the sternoclavicular joint and its microanatomical changes in response to osteoarthritic degeneration

Although the sternoclavicular joint shares structural similarities with the knee and hip joints as a diarthrodial joint, its biomechanics differ significantly due to its non-weight-bearing nature. Nevertheless, it is subject to considerable loading, leading to increased susceptibility to osteoarthritis, a prevalent condition characterized by the degeneration of the joint's articular surfaces and fibrocartilaginous intra-articular disc. The osteoarthritic degeneration of the fibrocartilaginous and cartilaginous surfaces of the sternoclavicular joint has been investigated, considering multiple factors. These include cell count, collagen alignment, surface fibrillation, cyst formation, and glycosaminoglycan content, with the findings deemed significant. However, current treatments for osteoarthritis of the sternoclavicular joint tend to focus on symptom management rather than active prevention of disease progression. Therefore, a detailed understanding of the anatomy, biomechanics, and morphological changes of the sternoclavicular joint during all stages of the osteoarthritic disease is essential for effective management to allow for maximum patient outcomes. This review explores the current literature on the anatomy of the sternoclavicular joint, starting with its structure and comparison to surrounding joints, biomechanics, and morphology, before considering the microanatomical changes that occur due to osteoarthritic degeneration. Early identification of osteoarthritic changes within this joint can enhance treatment and management outcomes before advancing joint degeneration, improving the quality of life for those affected.