Frozen shoulder, medically referred to as adhesive capsulitis, is a musculoskeletal disorder marked by pain and significant restriction in shoulder mobility.

This condition results from inflammation and tightening of the shoulder capsule—the connective tissue surrounding the shoulder joint—leading to stiffness and difficulty in performing everyday activities involving arm movement.

Though the exact cause remains unclear, frozen shoulder primarily affects individuals between 40 and 60 years of age, with a higher incidence in women and those suffering from systemic illnesses such as diabetes or thyroid disorders. Understanding the clinical course, underlying mechanisms, and therapeutic options is essential to effectively manage this debilitating condition.

Pathophysiology and Progression

At the core of frozen shoulder is inflammation and fibrosis of the shoulder joint capsule, which causes the tissue to thicken and contract. The normal capsule contains synovial fluid that lubricates and allows smooth movement within the ball-and-socket joint formed by the humerus, scapula, and clavicle.

When the capsule becomes inflamed, adhesions develop, reducing the joint space and limiting range of motion due to mechanical restriction and pain.

Frozen shoulder classically evolves through three overlapping stages: freezing, frozen, and thawing. During the freezing stage, significant pain is present with any shoulder movement, accompanied by progressive stiffness. This phase may persist from a few weeks to several months.

The frozen stage features reduced pain levels but pronounced stiffness, making arm movement substantially restricted; this stage can last from four to twelve months. Finally, in the thawing stage, shoulder mobility gradually improves, although recovery may take up to two years or longer in some cases.

Risk Factors and Etiology

Although the precise triggers of frozen shoulder are still under investigation, several risk factors and associated conditions have been identified. A period of immobilization following shoulder injury, surgery, or fracture significantly predisposes to adhesive capsulitis. Prolonged lack of movement contributes to capsular thickening and scar formation.

Systemic diseases such as diabetes mellitus exhibit a strong correlation with frozen shoulder development, with diabetic patients often experiencing more prolonged and severe symptoms. Thyroid dysfunction, Parkinson's disease, and cardiovascular conditions also appear to increase susceptibility.

The condition typically occurs without a clear provoking event, termed primary adhesive capsulitis, or secondarily following trauma or surgical procedures around the shoulder.

Clinical Manifestations

Patients with frozen shoulder report dull, aching pain localized around the shoulder and upper arm. This pain is often worse at night, disrupting sleep quality. As the condition advances, the range of shoulder motion diminishes markedly, with both active movement (self-initiated) and passive movement (movement by another person) being severely limited.

Common functional impairments include difficulty reaching overhead, dressing, or performing tasks requiring external rotation of the arm. Physical examination reveals restricted shoulder range of motion across all planes, often with muscle spasms and tenderness around the joint.

Diagnostic Evaluation

Diagnosis of frozen shoulder is predominantly clinical, based on history and physical examination demonstrating significant limitation in both active and passive shoulder movement without other identifiable causes such as arthritis or rotator cuff tear. Imaging studies, including X-rays, usually show normal joint spaces but are used to exclude other pathologies.

Magnetic resonance imaging (MRI) or ultrasound may be employed for detailed soft tissue evaluation if differential diagnoses are suspected.

Management and Therapeutic Strategies

Treatment aims to relieve pain and progressively restore shoulder motion. Conservative approaches form the cornerstone of management, including physical therapy focused on stretching and strengthening exercises. Controlled mobilization maintains joint flexibility and prevents further capsular contraction.

Pharmacologic interventions involve nonsteroidal anti-inflammatory drugs (NSAIDs) to reduce inflammation and corticosteroid injections directly into the joint capsule to diminish pain and swelling. In cases where conservative treatment is ineffective after several months, surgical options such as manipulation under anesthesia or arthroscopic capsular release may be considered to break adhesions and improve movement.

Dr. Randy Schwartzbard, MD, a board-certified podiatrist, states, "When people get this, they have a tremendous amount of pain from it."

Frozen shoulder, or adhesive capsulitis, represents a complex interplay of inflammation and fibrosis leading to painful stiffness and restricted movement of the shoulder joint. Progressing through distinct clinical stages, this condition significantly impacts daily functioning and quality of life.

Understanding its risk factors, pathology, and therapeutic options allows healthcare professionals to develop effective individualized treatment plans. While spontaneous recovery is common, active interventions encompassing physical therapy and medical management accelerate rehabilitation.

Continuous research advances aim to elucidate underlying mechanisms further, improving prevention and management strategies for this disabling musculoskeletal disorder.