Frozen shoulder, medically known as Adhesive Capsulitis, is a common and painful condition that severely limits the mobility of the shoulder joint. This ailment occurs when the connective tissue surrounding the shoulder tightens and thickens, restricting both active and passive range of motion. The condition typically progresses slowly, worsening over time before eventually resolving, usually within one to three years.
Understanding Adhesive Capsulitis
Adhesive capsulitis specifically targets the shoulder capsule, a strong layer of connective tissue that encases the glenohumeral joint. This capsule surrounds the ball (head of the humerus) and socket (glenoid), stabilizing the joint and holding the synovial fluid that lubricates movement. In an affected shoulder, the capsule undergoes an inflammatory process that progresses into fibroblastic proliferation.
This inflammation causes the capsule to thicken, contract, and form scar-like adhesions, restricting the space needed for the head of the humerus to move freely. The connective tissue, rich in collagen, becomes stiff and tight, mechanically blocking the joint’s ability to rotate and lift. This loss of motion is a defining characteristic of adhesive capsulitis, limiting movement whether the person attempts to move the arm themselves or someone else attempts to move it for them.
The Three Stages of Progression
The progression of adhesive capsulitis is generally divided into three distinct, overlapping stages that reflect the changing balance between pain and stiffness. The first phase is the Freezing Stage, characterized by increasing pain and the gradual loss of shoulder movement. This initial stage can last anywhere from six weeks to nine months, often causing pain that is worse at night and disrupts sleep.
Following the painful phase is the Frozen Stage, where the shoulder’s range of motion reaches its maximum restriction, but the pain begins to subside. While the stiffness peaks, simple daily tasks, such as reaching behind the back or overhead, become extremely difficult. This stiff phase typically lasts between four months and one year, representing the period of greatest physical limitation.
The final phase is the Thawing Stage, which marks the beginning of recovery as the shoulder’s mobility starts to return. During this phase, the stiffness gradually decreases, and the range of motion improves. This recovery can be the longest period, often lasting from five months up to two years.
Primary and Secondary Risk Factors
The causes of frozen shoulder are classified into two categories: primary and secondary. Primary adhesive capsulitis is considered idiopathic, meaning the exact cause is unknown and the condition develops spontaneously without a clear preceding event. Secondary adhesive capsulitis is linked to a known cause, such as a recent injury, surgery, or a period of immobilization, like wearing a sling after a fracture.
Certain demographic and systemic medical factors predispose individuals to developing the condition. It is most common in individuals between the ages of 40 and 60, and observed more frequently in women than in men. Systemic diseases represent the strongest risk factor, particularly endocrine disorders like diabetes mellitus and thyroid conditions. People with diabetes have a significantly higher risk, affected at a rate up to four times greater than the general population.
The link between diabetes and frozen shoulder is hypothesized to involve a process called non-enzymatic glycosylation. Chronically elevated blood sugar levels cause glucose molecules to attach to the collagen fibers within the shoulder capsule, leading to the formation of Advanced Glycation End products (AGEs). This process makes the collagen more rigid and less elastic, directly contributing to the thickening and contracture of the joint capsule. The longer the duration of diabetes and the poorer the glycemic control, the greater the likelihood of developing a more severe or recurrent case.
Management and Rehabilitation Strategies
Management of frozen shoulder focuses on controlling pain and restoring range of motion, with treatment tailored to the specific stage of progression. During the painful freezing stage, the primary goal is pain relief, often achieved through nonsteroidal anti-inflammatory drugs (NSAIDs) and targeted corticosteroid injections. Physical therapy at this time involves gentle range-of-motion exercises to maintain mobility without provoking further inflammation.
As the condition moves into the frozen and thawing stages, the focus of physical therapy shifts toward progressive stretching to restore lost motion. Therapists guide patients through exercises, including passive range of motion and mobilization techniques, designed to stretch the contracted capsule. Success during these later stages relies heavily on the patient’s adherence to a prescribed home exercise program.
For patients who do not respond to conservative management after several months, more advanced interventions may be considered.
Manipulation Under Anesthesia
Manipulation under anesthesia involves a surgeon forcefully moving the shoulder to break up the scar tissue and adhesions within the capsule while the patient is asleep.
Arthroscopic Capsular Release
Another option is an arthroscopic capsular release, a minimally invasive surgery where the tight portions of the joint capsule are precisely cut using small instruments. Both procedures aim to mechanically free the joint and accelerate the return to a functional range of motion.