From the Guidelines
Adhesive capsulitis, commonly known as frozen shoulder, is primarily caused by inflammation and thickening of the shoulder joint capsule, leading to stiffness and pain, with the exact cause often remaining unknown (idiopathic), but several risk factors increase susceptibility, including diabetes, thyroid disorders, cardiovascular disease, and Parkinson's disease, as well as prolonged immobilization of the shoulder following injury, surgery, or stroke 1. The condition can be triggered by various factors, including:
- Prolonged immobilization of the shoulder following injury, surgery, or stroke
- Previous shoulder trauma or surgery
- Certain medical conditions, such as diabetes, thyroid disorders, cardiovascular disease, and Parkinson's disease
- Women between 40-60 years old are more commonly affected than men The condition typically progresses through three phases: freezing (increasing pain), frozen (decreasing pain but increasing stiffness), and thawing (gradual improvement in range of motion) 1. Understanding these causes and risk factors is important for prevention strategies, especially for those with predisposing conditions who should maintain shoulder mobility whenever possible. It is also important to note that shoulder pain in certain conditions, such as polymyalgia rheumatica, might be due to a relapse or unrelated to the condition, such as osteoarthritis, adhesive capsulitis, or rotator cuff disease 1.
From the Research
Causes of Shoulder Adhesive Capsulitis (Frozen Shoulder)
- Adhesive capsulitis, also known as "frozen shoulder," is a common shoulder condition characterized by pain and decreased range of motion, especially in external rotation 2.
- It is predominantly an idiopathic condition, meaning that the cause is unknown, but it has an increased prevalence in patients with diabetes mellitus and hypothyroidism 2.
- The exact cause of adhesive capsulitis is not well understood, but it is thought to involve fibrosis and contracture of the joint capsule, leading to painful, gradual loss of active and passive shoulder motion 3.
Associated Conditions
- Adhesive capsulitis is often associated with other conditions, such as diabetes mellitus and hypothyroidism, which can increase the risk of developing the condition 2, 4.
- Male gender and diabetes mellitus have been associated with worse motion at the final evaluation of adhesive capsulitis treatment 4.
Underlying Mechanisms
- The natural history of adhesive capsulitis is a matter of controversy, but it is thought to involve a complex interplay of factors, including inflammation, fibrosis, and contracture of the joint capsule 3, 5.
- Central sensitization, which refers to an increased sensitivity of the nervous system, may also play a role in the development and maintenance of adhesive capsulitis, but this has not been fully studied 5.