Adhesive capsulitis of the shoulder
Adhesive capsulitis, also known as frozen shoulder, is a condition associated with shoulder pain and stiffness. It is a common shoulder ailment that is marked by pain and a loss of range of motion, particularly in external rotation. There is a loss of the ability to move the shoulder, both voluntarily and by others, in multiple directions. The shoulder itself, however, does not generally hurt significantly when touched. Muscle loss around the shoulder may also occur. Onset is gradual over weeks to months. Complications can include fracture of the humerus or biceps tendon rupture.The cause in most cases is unknown. The condition can also occur after injury or surgery to the shoulder. Risk factors include diabetes and thyroid disease. The underlying mechanism involves inflammation and scarring. The diagnosis is generally based on a persons symptoms and a physical exam. The diagnosis may be supported by an MRI. Adhesive capsulitis has been linked to diabetes and hypothyroidism, according to research. Adhesive capsulitis was five times more common in diabetic patients than in the control group, according to a meta-analysis published in 2016.The condition often resolves itself over time without intervention but this may take several years. While a number of treatments, such as NSAIDs, physical therapy, steroids, and injecting the shoulder at high pressure, may be tried, it is unclear what is best. Surgery may be suggested for those who do not get better after a few months. About 4% of people are affected. It is more common in people 40–60 years of age and in women.

Signs and symptoms
Symptoms include shoulder pain and limited range of motion although these symptoms are common in many shoulder conditions. An important symptom of adhesive capsulitis is the severity of stiffness that often makes it nearly impossible to carry out simple arm movements. Pain due to frozen shoulder is usually dull or aching and may be worse at night and with any motion.The symptoms of primary frozen shoulder have been described as having three or four stages. Sometimes a prodromal stage is described that can be present up to three months prior to the shoulder freezing. During this stage people describe sharp pain at end ranges of motion, achy pain at rest, and sleep disturbances.

Stage one: The "freezing" or painful stage, which may last from six weeks to nine months, and in which the patient has a slow onset of pain. As the pain worsens, the shoulder loses motion.
Stage two: The "frozen" or adhesive stage is marked by a slow improvement in pain but the stiffness remains. This stage generally lasts from four to twelve months.
Stage three: The "thawing" or recovery, when shoulder motion slowly returns toward normal. This generally lasts from 5 to 26 months.Physical exam findings include restricted range of motion in all planes of movement in both active and passive range of motion. This contrasts with conditions such as shoulder impingement syndrome or rotator cuff tendinitis in which the active range of motion is restricted but passive range of motion is normal. Some exam maneuvers of the shoulder may be impossible due to pain.

Causes
The causes of adhesive capsulitis are incompletely understood; however, there are several factors associated with higher risk. Risk factors for secondary adhesive capsulitis include injury or surgery leading to prolonged immobility. Risk factors for primary, or idiopathic adhesive capsulitis include many systemic diseases, such as diabetes mellitus, stroke, lung disease, connective tissue diseases, thyroid disease, heart disease, autoimmune disease, and Dupuytrens contracture. Both type 1 diabetes and type 2 diabetes are risk factors for the condition.

Primary
Primary adhesive capsulitis, also known as idiopathic adhesive capsulitis, occurs with no known trigger. It is more likely to develop in the non-dominant arm.

Secondary
Adhesive capsulitis is called secondary when it develops after an injury or surgery to the shoulder.

Pathophysiology
The underlying pathophysiology is incompletely understood, but is generally accepted to have both inflammatory and fibrotic components. The hardening of the shoulder joint capsule is central to the disease process. This is the result of scar tissue (adhesions) around the joint capsule. There also may be a reduction in synovial fluid, which normally helps the shoulder joint, a ball and socket joint, move by lubricating the gap between the humerus and the socket in the shoulder blade. In the painful stage (stage I), there is evidence of inflammatory cytokines in the joint fluid. Later stages are characterized by dense collagenous tissue in the joint capsule.Under the microscope, the appearance of the affected shoulder joint capsule tissue is similar to the appearance of the tissue that restricts finger movement in Dupuytrens contracture.

Diagnosis
Adhesive capsulitis can be diagnosed by history and physical exam. It is often a diagnosis of exclusion, as other causes of shoulder pain and stiffness must first be ruled out. On physical exam, adhesive capsulitis can be diagnosed if limits of the active range of motion are the same or similar to the limits to the passive range of motion. The movement that is most severely inhibited is external rotation of the shoulder.Imaging studies are not required for diagnosis, but may be used to rule out other causes of pain. Radiographs will often be normal, but imaging features of adhesive capsulitis can be seen on ultrasound or non-contrast MRI. Ultrasound and MRI can help in diagnosis by assessing the coracohumeral ligament, with a width of greater than 3 mm being  60% sensitive and 95% specific for the diagnosis. Shoulders with adhesive capsulitis also characteristically fibrose and thicken at the axillary pouch and "rotator interval", best seen as a dark signal on T1 sequences with edema and inflammation on T2 sequences. A finding on ultrasound associated with adhesive capsulitis is hypoechoic material surrounding the long head of the biceps tendon at the rotator interval, reflecting fibrosis. In the painful stage, such hypoechoic material may demonstrate increased vascularity with Doppler ultrasound.Grey-scale ultrasound can play a key role in timely diagnosis of adhesive capsulitis due to its high sensitivity and specificity. It is also widely available, convenient, and cost efficient. Thickening in the coracohumeral ligament, inferior capsule/ axillary recess capsule, and rotator interval abnormality, as well as restriction in range of motion in the shoulder can be detected using ultrasound. The range of motion is prohibited due to scapulohumeral rhythm changes occurring in the shoulder joint. The altered scapular kinematics can restrict anterior and posterior tilting, downward rotation and depression as well as external rotation. All of these restrictions lead the scapula to be excessively upwardly rotated. The restriction of the scapular posterior tilt is due to tightness in the lower serratus anterior, anterior capsule and the pectoralis minor. Downward rotation and depression are restricted due to the tightness of the rhomboids, upper trapezius and the superior capsule. Respective sensitivity values were 64.4, 82.1, 82.6, and 94.3, and respective specificity levels were 88.9, 95.7, 93.9, and 90.9.

Management
Management of this disorder focuses on restoring joint movement and reducing shoulder pain, involving medications, occupational therapy, physical therapy, or surgery. Treatment may continue for months; there is no strong evidence to favor any particular approach. The main treatment for adhesive capsulitis is a trial of conservative therapies, including analgesia, exercise, physiotherapy, oral nonsteroidal anti-inflammation drugs, and intra-articular corticosteroid injections.Medications such as NSAIDs can be used for pain control. Corticosteroids are used in some cases either through local injection or systemically. In the short term, intra-articular corticosteroid injections were more effective in pain alleviation. Unfortunately, this pain reduction was not long-lasting. In both the short and long term, intra-articular corticosteroid injections improved passive range of motion (ROM). Oral steroids may provide short-term benefits in range of movement and pain but have side effects such as hyperglycemia. Steroid injections compared to physical therapy have a similar effect in improving shoulder function and decreasing pain. The benefits of steroid injections appear to be short-term. The results of this study imply that using an IA corticosteroid early in individuals with frozen shoulder who have had it for less than a year had a better prognosis. To increase the chances of recovery, this treatment should be combined with a home exercise program. Oral corticosteroids should not be used consistently to treat adhesive capsulitis because of the dangers associated with long-term use and the lack of long-term benefit.The role for occupational therapy (OT) in adhesive capsulitis is dependent on restrictions on daily activities, pain, and limitations the person is experiencing; an occupational therapist usually makes an initial evaluation. Pain and limited joint mobility are primary complaints that impact a persons daily life. OT will usually start by using a preparatory method, like physical agent modalities to be used as part of a comprehensive occupational therapy program. The occupational therapist may teach strengthening exercises and provide a home exercise program. The goal of OT would be for the client to resume meaningful functional daily activities.The role for physical therapy in adhesive capsulitis is not settled. Physical therapy is used as an initial treatment in adhesive capsulitis with the use of range of motion (ROM) exercises and manual therapy techniques to restore range and function. A low-dose corticosteroid injection and home exercise programs in those with symptoms for less than 6 months may be useful. There may be some benefit with manual therapy and stretching as part of a rehabilitation program, but, due to the time required, such use should be carefully considered. Physical therapists may utilize joint mobilization directly at the glenohumeral joint to decrease pain, increase function, and increase range of motion as another form of treatment. There are some studies that have shown that intensive passive stretching can promote healing. Additional interventions include modalities such as ultrasound, shortwave diathermy, laser therapy and electrical stimulation. Another osteopathic technique used to treat the shoulder is called the Spencer technique. Mobilization techniques and other therapeutic modalities are most commonly used by physical therapists; however, there is not strong evidence that these methods can change the course of the disease.If these measures are unsuccessful, more aggressive interventions such as surgery can be trialed.  Manipulation of the shoulder under general anesthesia to break up the adhesions is sometimes used. Hydrodilatation or distension arthrography is controversial. However, some studies show that arthrographic distension may play a positive role in reducing pain and improve range of movement and function. Surgery to cut the adhesions (capsular release) may be indicated in prolonged and severe cases; the procedure is usually performed by arthroscopy. Surgical evaluation of other problems with the shoulder, e.g., subacromial bursitis or rotator cuff tear, may be needed. Resistant adhesive capsulitis may respond to open release surgery. This technique allows the surgeon to find and correct the underlying cause of restricted glenohumeral movement such as contracture of coracohumeral ligament and rotator interval. Physical therapy may achieve improved results after surgical procedure and postoperative rehabilitation.Physical therapy is an effective procedure that provides essential exercises to improve range of motion. Patients who receive the proper training from an authorized physiotherapist can perform these exercises independently at home. The physiotherapy treatment for frozen shoulder will include manual therapy to mobilize the affected joints and release their muscles. "Pendulum stretch", "finger walk", "towel stretch", "armpit stretch" and "crossbody reach" are some essential mobility exercises specifically designed to improve the shoulder mobility of patients with frozen shoulders. There are also limited case reports of therapy utilizing vibration platforms obtaining fast results, not as a post-operative aid, but instead of surgery.Acupuncture has been found to decrease pain levels and improve shoulder function and range of motion, particularly in shoulder flexion. Acupuncture combined with shoulder exercises was found to be more effective than shoulder exercise alone. However, further studies with longer follow-up times are needed to assess mid- and long term benefits.

Prognosis
Most cases of adhesive capsulitis are self limiting, but may take 1 to 3 years to fully resolve. Pain and stiffness may not completely resolve in 20 to 50 per cent of affected people.

Epidemiology
Adhesive capsulitis newly affects approximately 0.75% to 5.0% percent of people a year. Rates are higher in people with diabetes (10–46%). Following breast surgery, some known complications include loss of shoulder range of motion (ROM) and reduced functional mobility in the involved arm. Occurrence is rare in children and people under 40. with the highest prevalence between 40 and 70 years of age. The condition is more common in women than in men (70% of patients are women aged 40–60). People with diabetes, stroke, lung disease, rheumatoid arthritis, or heart disease are at a higher risk for frozen shoulder. Symptoms in people with diabetes may be more protracted than in the non-diabetic population.

See also
Calcific tendinitis
Milwaukee shoulder syndrome

References


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