Adhesive Capsulitis (Frozen Shoulder)

Overview

Adhesive capsulitis, commonly called frozen shoulder, is a painful disorder characterised by progressive restriction of both active and passive glenohumeral movement. External rotation is typically affected earliest and most prominently.

The disorder develops through inflammation, fibrosis and contracture of the glenohumeral joint capsule and surrounding ligaments. Symptoms can substantially impair sleep, dressing, grooming, reaching overhead and other everyday activities. Although adhesive capsulitis often improves over time, recovery may take months to years and may remain incomplete in some patients.

Anatomy & Physiology

The glenohumeral joint is formed by the humeral head and the shallow glenoid cavity. Its large range of movement depends on a relatively loose fibrous capsule supported by the glenohumeral ligaments, coracohumeral ligament, rotator cuff muscles and surrounding soft tissues.

The joint capsule attaches around the glenoid and anatomical neck of the humerus. Inferiorly, the capsule forms the axillary recess, which unfolds during shoulder elevation.

The rotator interval is the triangular area between the supraspinatus and subscapularis tendons. It contains the coracohumeral ligament, superior glenohumeral ligament and long head of the biceps tendon. Normal flexibility within this region is particularly important for external rotation.

Coordinated glenohumeral and scapulothoracic movement permits shoulder elevation. When glenohumeral movement becomes restricted, increased scapular movement may partially compensate but cannot restore normal shoulder function.

Aetiology & Risk Factors

Aetiology

Adhesive capsulitis may be classified according to whether an identifiable precipitating factor is present.

Primary adhesive capsulitis develops without a clear local cause and is considered idiopathic.

Secondary adhesive capsulitis develops in association with:

• Shoulder trauma
• Shoulder or chest surgery
• Prolonged upper-limb immobilisation
• Rotator cuff disease
• Other painful shoulder conditions that reduce movement
• Systemic disorders associated with capsular fibrosis

Reduced shoulder movement following injury or surgery may contribute to secondary disease, but not every stiff or painful shoulder represents adhesive capsulitis.

Risk Factors

Recognised associations include:

• Diabetes mellitus
• Thyroid disease
• Female sex
• Age between approximately 40 and 60 years
• Previous adhesive capsulitis in the opposite shoulder
• Prolonged shoulder immobilisation
• Previous shoulder trauma or surgery
• Neurological disease associated with impaired upper-limb movement

Diabetes is one of the strongest recognised systemic associations. People with diabetes have an increased prevalence of adhesive capsulitis and may experience more prolonged symptoms or incomplete recovery.

Pathophysiology

The pathological process usually begins with inflammation of the glenohumeral synovium and joint capsule. This is followed by fibroblast proliferation, collagen deposition, capsular thickening and progressive contracture.

Important pathological changes include:

• Thickening and contracture of the coracohumeral ligament
• Fibrosis of the rotator interval
• Thickening of the anterior and inferior joint capsule
• Reduced capacity of the axillary recess
• Adhesion of capsular folds
• Reduced capsular compliance and joint volume

Early inflammation contributes to pain, particularly at night and at the limits of movement. Progressive fibrosis then produces mechanical restriction of the humeral head within the contracted capsule.

Contracture of the rotator interval and coracohumeral ligament particularly restricts external rotation. Inferior capsular involvement limits elevation and abduction.

Clinical Phases

The clinical course is traditionally described in three overlapping phases. The duration and severity of each phase vary considerably.

Freezing phase

Pain is prominent and progressively worsens, often disturbing sleep. Movement gradually becomes more restricted.

Frozen phase

Stiffness and functional restriction predominate. Pain may lessen at rest but persists at the limits of movement.

Thawing phase

Movement gradually improves as capsular restriction resolves. Recovery may be slow and is not always complete.

The phases are descriptive rather than rigid. Patients may have substantial pain and stiffness simultaneously and should not be denied appropriate treatment because they do not fit neatly into one phase.

Clinical Manifestations

Adhesive capsulitis causes progressive shoulder pain and stiffness with restriction of both active and passive movement.

The onset is usually gradual. Patients may report:

• Diffuse shoulder pain, often poorly localised
• Progressive stiffness over weeks or months
• Night pain and difficulty sleeping on the affected side
• Pain at the limits of shoulder movement
• Difficulty reaching overhead
• Difficulty reaching behind the back
• Difficulty dressing, fastening a bra or placing an arm into a sleeve
• Difficulty washing or combing the hair
• Difficulty reaching a back pocket
• Reduced ability to perform work, sport or household activities

Pain may radiate into the upper arm but usually does not extend below the elbow unless another disorder is present.

Clinical Examination

• Restriction of both active and passive glenohumeral movement
• Marked restriction of external rotation with the arm by the side
• Restriction of abduction and internal rotation
• Pain at the end of the available range
• Compensatory scapular movement during attempted elevation
• Relatively preserved strength when tested within the available painless range
• No focal neurological deficit attributable to adhesive capsulitis

The shoulder may be difficult to examine during the pain-dominant phase because pain and guarding can exaggerate the apparent loss of movement.

Diagnosis

Adhesive capsulitis is primarily a clinical diagnosis. It is supported by gradual shoulder pain and stiffness together with restriction of both active and passive movement, particularly external rotation.

No single blood test or imaging finding confirms the diagnosis. Investigations are mainly used to exclude alternative causes of shoulder stiffness.

Plain Radiography

Plain shoulder radiographs are commonly obtained when the diagnosis is uncertain or symptoms are atypical. Radiographs are usually normal in adhesive capsulitis

Ultrasound

Ultrasound is not required to diagnose adhesive capsulitis. It may be useful when rotator cuff disease, subacromial bursitis or another soft-tissue disorder is suspected. It can also guide intra-articular corticosteroid injection.

Magnetic Resonance Imaging

MRI is not routinely required. Findings may include capsular thickening, coracohumeral ligament thickening, rotator interval fibrosis and oedema within the axillary recess. These findings are supportive rather than independently diagnostic.

MRI may be appropriate when the presentation is atypical or when significant rotator cuff disease, tumour, osteonecrosis or another structural disorder is suspected.

Laboratory Investigations

Routine laboratory testing is unnecessary in an otherwise typical presentation. Testing for diabetes or thyroid dysfunction may be considered when clinically indicated by the history, examination or absence of previous screening.

Differential Diagnosis

Important differential diagnoses include:

• Glenohumeral osteoarthritis
• Rotator cuff tear or tendinopathy
• Subacromial pain syndrome
• Calcific tendinopathy
• Cervical radiculopathy
• Parsonage–Turner syndrome
• Previous fracture or dislocation
• Septic arthritis
• Inflammatory arthritis
• Osteonecrosis of the humeral head
• PMR

Fever, systemic illness, significant trauma, deformity, rapidly progressive symptoms, neurological deficit or a history of malignancy should prompt investigation for an alternative diagnosis.

Treatment

Treatment aims to control pain, preserve function and gradually restore shoulder movement. Management should consider symptom severity, disease phase, functional requirements and associated conditions.

Education and Activity Modification

Patients should be advised that:

• Recovery is often gradual
• Normal daily use should continue within tolerable limits
• Complete immobilisation can worsen stiffness
• Exercises should be regular but should not repeatedly provoke severe or prolonged pain
• Diabetes and other associated disorders should be appropriately managed

Analgesia

Paracetamol or a non-steroidal anti-inflammatory drug may be considered for short-term pain relief when clinically appropriate and not contraindicated. Analgesia may improve sleep and allow participation in rehabilitation but does not directly reverse capsular fibrosis.

Physiotherapy and Exercise

Physiotherapy may include:

• Education about the expected course
• Gentle active and passive range-of-motion exercises
• Stretching within tolerable limits
• Scapular control exercises
• Progressive strengthening as pain and movement improve
• A structured home-exercise program

Aggressive stretching during a highly painful phase may worsen symptoms. The intensity of mobilisation should therefore be adjusted to pain irritability and the stage of the disorder.

Intra-articular Corticosteroid Injection

Glenohumeral corticosteroid injection can provide short-term improvement in pain and function, particularly during the early pain-dominant phase. Evidence supports intra-articular corticosteroid injection as an effective non-operative treatment, with additional benefit when combined with an exercise or physiotherapy program.⁴

Hydrodilatation

Hydrodilatation involves image-guided injection of fluid into the glenohumeral joint to distend the contracted capsule, usually with local anaesthetic and corticosteroid.

It may provide short-term improvement in disability and passive external rotation. However, studies vary in technique, and its additional benefit over intra-articular corticosteroid injection alone remains uncertain.⁵

Manipulation Under Anaesthesia

Manipulation under anaesthesia uses controlled force to disrupt capsular adhesions and improve movement. It is generally reserved for persistent, functionally limiting disease.

Arthroscopic Capsular Release

Arthroscopic capsular release permits controlled division of contracted capsular structures under direct visualisation. It may be considered when substantial pain and restriction persist despite appropriate conservative treatment.

Complications & Prognosis

Complications

Adhesive capsulitis may result in:

• Persistent pain
• Chronic restriction of shoulder movement
• Sleep disturbance
• Reduced ability to work, exercise or perform self-care
• Compensatory scapular or cervical discomfort
• Loss of upper-limb strength through disuse
• Psychological distress related to prolonged pain and disability

Treatment-related complications may occur following corticosteroid injection, hydrodilatation, manipulation under anaesthesia or surgery.

Prognosis

Most patients improve with time and non-operative management, but the course is variable. Recovery may require many months or several years, and some patients retain residual pain or movement restriction.^1,3

A previous assumption that every untreated frozen shoulder resolves completely within a predictable period is not supported by the available evidence. Earlier recognition and appropriate symptom-directed treatment may reduce pain and disability while recovery occurs.

Diabetes is associated with a greater likelihood of persistent symptoms, reduced final range of movement and a less favourable treatment response.² Adhesive capsulitis may subsequently affect the opposite shoulder, although recurrence in the same shoulder is uncommon.

References

1. Le HV, Lee SJ, Nazarian A, Rodriguez EK. Adhesive capsulitis of the shoulder: review of pathophysiology and current clinical treatments. Shoulder Elbow. 2017;9(2):75–84. doi:10.1177/1758573216676786
2. Zreik NH, Malik RA, Charalambous CP. Adhesive capsulitis of the shoulder and diabetes: a meta-analysis of prevalence. Muscles Ligaments Tendons J. 2016;6(1):26–34. doi:10.11138/mltj/2016.6.1.026
3. Rangan A, Goodchild L, Gibson J, Brownson P, Thomas M, Rees J, et al. Frozen shoulder. Shoulder Elbow. 2015;7(4):299–307. doi:10.1177/1758573215601779
4. Challoumas D, Biddle M, McLean M, Millar NL. Comparison of treatments for frozen shoulder: a systematic review and meta-analysis. JAMA Netw Open. 2020;3(12):e2029581. doi:10.1001/jamanetworkopen.2020.29581
5. Poku D, Hassan R, Migliorini F, Maffulli N. Efficacy of hydrodilatation in frozen shoulder: a systematic review and meta-analysis. Br Med Bull. 2023;147(1):121–147. doi:10.1093/bmb/ldad018