Inflammation then fibrosis of the glenohumeral capsule | Painful global loss of movement | Clinical diagnosis | Loss of passive external rotation is the key sign | Usually self-limiting but slow
- It is a clinical diagnosis: painful, progressive, global restriction of shoulder movement with loss of both active AND passive range - the loss of passive external rotation with the arm by the side is the signature finding
- The pathology is inflammation followed by fibrosis of the glenohumeral capsule, especially the rotator interval and coracohumeral ligament, producing a thickened, contracted, low-volume joint
- Diabetes is the strongest association: diabetic frozen shoulder is more common, often bilateral, more resistant to treatment, and more likely to need a procedure
- Imaging is mainly to exclude other causes (osteoarthritis, a locked posterior dislocation, calcific disease): the radiograph is usually normal, and MRI or arthrogram changes are supportive rather than essential
- Most cases are self-limiting but recovery is slow (often 1 to 3 years); first-line care is pain control, an intra-articular steroid injection early, and stretching physiotherapy, with hydrodilatation, manipulation under anaesthesia or capsular release reserved for resistant cases
- “Loss of PASSIVE external rotation with the arm at the side is the discriminating sign - it separates true capsular restriction from a stiff shoulder caused by pain alone or a rotator cuff problem
- “A normal radiograph supports the diagnosis; an abnormal one points you to a secondary cause such as glenohumeral osteoarthritis or a missed posterior dislocation
- “Always check the glucose - new bilateral frozen shoulder can be the presenting sign of undiagnosed diabetes
- “An early intra-articular steroid injection gives the biggest gains in the painful freezing stage; physiotherapy alone works more slowly
Clinical Imaging
The contracted, low-volume joint - the hallmark of a frozen shoulder
Diagnose on the history and examination: painful, progressive, global restriction of shoulder movement with loss of both active and passive range. There is no single test or scan that makes the diagnosis - imaging is mainly to exclude other causes.
Loss of passive external rotation with the arm at the side is the signature sign. A capsular contracture restricts the passive range; pain or a cuff tear alone usually does not block passive external rotation in the same way. This is the most examined discriminator.
Diabetes is the strongest risk factor. Diabetic frozen shoulder is more common, frequently bilateral, more resistant, and more likely to need a procedure. New bilateral disease should prompt a glucose check.
A normal radiograph supports the diagnosis. An abnormal one warns of a secondary cause - glenohumeral osteoarthritis, a locked posterior dislocation (loss of external rotation after a seizure or shock), or calcific disease - that needs different treatment.
At a Glance
The exam essentials are simple to state: frozen shoulder is a clinical diagnosis, the key sign is loss of passive external rotation, the strongest risk factor is diabetes, imaging is mainly to exclude other causes, and treatment escalates from pain control and an early injection through physiotherapy and hydrodilatation to surgical release only for resistant disease.
Memory aids
DIABETESRisk Factors for Frozen Shoulder
Hook:The risks spell DIABETES - fitting, because diabetes is the single most important risk factor for a frozen shoulder.
FFTThe Three Stages
Hook:Freeze, Frozen, Thaw - FFT. Pain leads, stiffness follows, then slow recovery: the natural history of a frozen shoulder.
PAINSEscalating Treatment Ladder
Hook:Treat the PAINS in order - start simple (relief, injection, physio) and escalate to hydrodilatation then surgery only when needed.
Overview
Adhesive capsulitis - the frozen shoulder - is a common, painful condition in which the glenohumeral joint capsule becomes inflamed and then fibrotic, so the shoulder gradually stiffens and loses movement in all directions. It typically affects people aged 40 to 60, is slightly more common in women, and is strongly linked to diabetes.
The hallmark is painful, progressive loss of both active and passive movement, with external rotation usually the first and worst affected. The natural history runs through three overlapping stages - freezing (painful), frozen (stiff), and thawing (recovering) - and most cases eventually settle, although recovery is slow and a minority are left with some lasting stiffness.
For the exam, the recurring themes are: what is happening in the capsule (inflammation then fibrosis), how to recognise it clinically (and separate it from the things it mimics), and how the evidence guides an escalating treatment ladder.
Pathophysiology
The disease process is best understood as inflammation that turns into fibrosis. According to PubMed, current concept reviews describe the pathology of frozen shoulder as capsular inflammation followed by fibrosis and contracture, with the cause of primary (idiopathic) disease still unknown.
Where the disease lives:
- The rotator interval - the triangular space at the front of the joint between the supraspinatus and subscapularis tendons - and the coracohumeral ligament within it are affected early. Contracture here limits external rotation, which is why external rotation is lost first and most severely.
- The anterior and inferior capsule, including the axillary recess, thickens and contracts, reducing the overall joint volume - the small, tight joint seen on an arthrogram.
The cellular story:
| Step | What happens | Result |
|---|---|---|
| Inflammation | Synovial and capsular inflammation with increased inflammatory cytokines and new blood vessel formation | Pain (the painful freezing stage), worse at night |
| Fibroblast activation | Fibroblasts proliferate and transform into contractile myofibroblasts, laying down dense, disorganised collagen | A thickened, less elastic capsule |
| Contracture | The myofibroblast-rich capsule actively contracts and the rotator interval tightens | Loss of movement, especially external rotation - the frozen stage |
| Remodelling | Over many months the fibrotic tissue slowly remodels and softens | Gradual return of movement - the thawing stage |
The myofibroblast point is high-yield and explains why a frozen shoulder behaves like other fibrotic, contractile conditions - there is a recognised overlap with Dupuytren disease, which shares the same myofibroblast-driven fibrosis. It also explains why forcing movement against an actively contracting, inflamed capsule early on is unhelpful and painful.
Classification
Two ways of classifying frozen shoulder matter for the exam: by cause (primary versus secondary), and by clinical stage.
Primary (idiopathic) frozen shoulder has no identifiable cause. The international (ISAKOS) terminology reserves the term "frozen shoulder" for this idiopathic stiff shoulder.
Secondary frozen shoulder follows a known cause and is better called a secondary stiff shoulder. Causes include:
- Intrinsic - shoulder pathology such as a rotator cuff tear or calcific tendinitis.
- Extrinsic - a remote cause such as immobilisation after a wrist fracture, stroke, or cardiac/thoracic surgery.
- Systemic - diabetes and thyroid disease, which both predispose to the picture.
The distinction matters because a secondary stiff shoulder needs the underlying cause treated as well, and may behave differently from idiopathic disease.
Clinical Presentation and Examination
History. A patient (often 40 to 60, frequently with diabetes) describes shoulder pain that came on gradually with no major injury, is worse at night and on movement, and is followed by progressive stiffness. Ask specifically about diabetes, thyroid disease, a previous frozen shoulder on the other side, and any period of immobilisation.
Examination - the key is passive movement:
| Finding | What you see | Why it matters |
|---|---|---|
| Global restriction | Reduced movement in all directions, active AND passive | Distinguishes true capsular restriction from pain-limited movement |
| Loss of passive external rotation | With the arm at the side, passive external rotation is markedly reduced | The signature sign - a capsular contracture, not just pain or weakness |
| Normal strength (when testable) | Power is preserved once pain is accounted for | Helps separate it from a large rotator cuff tear |
| Scapulothoracic substitution | The patient shrugs and uses the scapula to lift the arm | Confirms the glenohumeral joint itself is the limited part |
The single most useful test is passive external rotation with the arm at the side. If passive external rotation is preserved, think again - pain inhibition or a rotator cuff problem can mimic a frozen shoulder, but they do not usually block passive external rotation the way a contracted capsule does. Lost passive external rotation also raises the spectre of a locked posterior dislocation after a seizure or electric shock, so always look at a radiograph.
Investigations
Frozen shoulder is a clinical diagnosis; investigations are used to exclude other causes and to support the diagnosis, not to make it.
Usually normal in primary disease - this supports the diagnosis. Their main value is to exclude glenohumeral osteoarthritis, a locked posterior dislocation, and calcific deposits. Always get an axillary or modified axillary view so a posterior dislocation is not missed.
Check glucose / HbA1c - undiagnosed diabetes is common - and consider thyroid function. There is no blood test for frozen shoulder itself.
Mainly to look for other pathology (a cuff tear, calcific disease). It can show thickening at the rotator interval and restricted movement but is operator-dependent and not required for diagnosis.
Supportive findings include a thickened coracohumeral ligament and rotator interval, thickened inferior capsule / axillary recess, and on arthrography a reduced joint volume. Reserve MRI for when the diagnosis is unclear or another problem is suspected.
The imaging gallery at the top of this page shows the classic supportive findings: the contracted joint on arthrogram, the thickened coracohumeral ligament, and the thickened axillary pouch.
Management
Treatment is an escalating ladder. The guiding principle is that frozen shoulder is usually self-limiting, so most patients are managed without surgery, with procedures reserved for resistant or severely disabling disease. Match the treatment to the stage: injection helps most in the painful freezing stage; stretching, hydrodilatation, and release target the stiff frozen stage.
- Education and reassurance - explain the natural history and the long but generally favourable course. This alone changes expectations and reduces distress.
- Analgesia and NSAIDs - for pain control, particularly in the painful freezing stage.
- Intra-articular corticosteroid injection - most effective early, when pain dominates. It gives faster pain relief and earlier improvement than physiotherapy alone, although the long-term difference narrows.
- Physiotherapy - gentle, progressive stretching within a comfortable range. Forced, aggressive stretching of an inflamed capsule is counterproductive early on.
This combination - an early injection plus structured physiotherapy - is the backbone of treatment and is what most patients need.
Aggressive stretching or manipulation during the painful inflammatory (freezing) stage worsens pain and can provoke more fibrosis. Manipulation under anaesthesia in osteoporotic or diabetic patients carries a real risk of humeral fracture, dislocation, and cuff injury. Time the intervention to the stage, and choose a controlled release over a forceful manipulation when the bone or capsule is at risk.
Surgical Technique - Arthroscopic Capsular Release
The aim is a controlled, complete release of the contracted capsule, replacing the uncontrolled tearing of a manipulation. Release the diseased tissue, restore range on the table, then protect the result with early, structured physiotherapy so the capsule does not simply re-scar.
Complications
Complications arise both from the disease and from its treatment.
| Complication | Who and when | What to do |
|---|---|---|
| Persistent stiffness | A minority, especially diabetics | Escalate the treatment ladder; counsel on the long course |
| Recurrence / contralateral disease | Diabetics and prior frozen shoulder | Warn the patient; treat the other shoulder on its merits |
| Humeral fracture | Manipulation under anaesthesia in osteoporotic or diabetic bone | Prefer a controlled release; manipulate gently or avoid in fragile bone |
| Dislocation / cuff or labral tear | During forceful manipulation | Controlled technique; recognise and treat the injury |
| Axillary nerve injury | During inferior capsular release | Stay close to the capsule and protect the nerve inferiorly |
| Steroid-related effects | After injection, especially in diabetics | Warn diabetics about a transient rise in blood glucose; strict asepsis |
Rehabilitation and Recovery
Rehabilitation is central, not an afterthought - both as primary treatment and after any procedure.
- Primary physiotherapy uses gentle, progressive stretching within a comfortable range, matched to the stage. Early on, the goal is to maintain range without provoking the inflamed capsule; later, the goal is to regain range as the capsule remodels.
- After manipulation or release, start immediate, intensive, supervised physiotherapy to hold the gains - the result is lost if the capsule re-scars.
- Home exercise between sessions is essential; a frozen shoulder is treated mostly by the patient at home.
- Expectations: most regain good, functional movement, but recovery is slow (often many months to a few years), and a minority keep some residual stiffness.
Outcomes and Prognosis
The overall prognosis is good but slow. Most patients improve substantially, whether treated conservatively or with a procedure, and the headline message of the best randomised evidence is that the different treatments end up close to each other by a year.
- Natural history: primary frozen shoulder is usually self-limiting, but recovery commonly takes 1 to 3 years, and a minority are left with some lasting restriction that is often well tolerated.
- Diabetes worsens the outlook: diabetic frozen shoulder is more resistant, more often bilateral, and more likely to need a procedure and to recover incompletely.
- Treatments converge: in secondary care, manipulation, capsular release, and structured physiotherapy with steroid injection all produced similar shoulder scores at 12 months, so the choice rests on risk and cost as much as on outcome.
Clinical Relevance
Frozen shoulder is one of the commonest shoulder complaints in clinic and a favourite exam topic because it tests clinical reasoning rather than fancy imaging. The examiner wants to see that you can diagnose it clinically (global loss of movement, lost passive external rotation), exclude the mimics (osteoarthritis, locked posterior dislocation, cuff tear) with a sensible history, examination and radiograph, recognise the diabetes link and check a glucose, and apply an evidence-based escalating ladder of treatment - reassurance and injection first, surgery last and only for resistant disease. Getting the passive external rotation sign and the escalation logic right is what separates a safe answer from a weak one.
Evidence Base
According to PubMed, the following studies underpin the modern management of frozen shoulder.
Surgery versus Physiotherapy plus Steroid for Frozen Shoulder (UK FROST RCT)
- Multicentre, pragmatic, three-arm RCT of 503 adults with primary frozen shoulder across 35 UK hospitals
- Manipulation under anaesthesia versus arthroscopic capsular release versus early structured physiotherapy plus steroid injection
- Oxford Shoulder Scores at 12 months were similar across all three groups; no treatment was clinically superior
- Arthroscopic capsular release carried more serious adverse events; manipulation under anaesthesia was the most cost-effective option
Manual Therapy and Exercise for Adhesive Capsulitis (Cochrane Review)
- Systematic review of 32 randomised trials (1836 participants)
- Combined manual therapy and exercise for six weeks probably gives LESS short-term improvement than a glucocorticoid injection (pain difference about 26 points on a 100-point scale at seven weeks)
- Differences between manual therapy/exercise and injection were not clinically important by six and twelve months
- After arthrographic distension, manual therapy and exercise gave greater patient-reported success and active abduction at six weeks
Shoulder Stiffness - Current Concepts and Terminology (ISAKOS Review)
- International consensus reserving 'frozen shoulder' for the idiopathic stiff shoulder and 'secondary stiff shoulder' for a known cause
- Describes the pathophysiology as capsular fibrosis and inflammation with chondrogenesis, cause still unknown
- Conservative treatment (pain control, injection with or without distension, physiotherapy) is first-line
- For refractory stiffness, arthroscopic capsular release is preferred over manipulation because of the lower risk of manipulation-related complications
Hydrodilatation and Bursal Steroid plus Physiotherapy versus Physiotherapy Alone (RCT)
- Single-blind RCT of 70 patients with freezing-stage frozen shoulder
- Hydrodilatation plus subdeltoid bursal steroid, mobilisation and physiotherapy versus usual-care physiotherapy alone
- The combination group had significantly better pain, disability (SPADI), range of motion and self-assessment scores
- Benefits were significant and persisted at one, two, four and six months
Exam Viva Scenarios
Practise clinical reasoning and management decisions out loud
“A 52-year-old woman presents with several months of right shoulder pain, worse at night, and increasing stiffness, with no injury. How would you assess her and what is your diagnosis?”
Likely diagnosis: This is the classic picture of a primary frozen shoulder - middle-aged, gradual onset, night pain, progressive stiffness, no trauma.
History: I would ask about diabetes and thyroid disease, any previous frozen shoulder on the other side, and any period of immobilisation, as these are the key risk factors.
Examination: The crucial finding is global restriction of both active AND passive movement, with loss of passive external rotation with the arm at the side - that is the signature of a capsular contracture rather than pain alone or a cuff problem. I would check that strength is preserved once pain is accounted for.
Investigations: Frozen shoulder is a clinical diagnosis. I would get a radiograph including an axillary view, mainly to exclude glenohumeral osteoarthritis and a locked posterior dislocation - I expect it to be normal. I would also check her glucose, because undiagnosed diabetes is common.
“A 58-year-old man with type 2 diabetes has a frozen shoulder that has not improved despite an injection and three months of physiotherapy. He still has severe stiffness and disability. How do you proceed?”
Reassess: First confirm this is still a frozen shoulder, that he has genuinely engaged with physiotherapy, and that there is no missed secondary cause. Diabetic frozen shoulder is known to be more resistant.
Escalate the ladder: The next steps are hydrodilatation (distending the capsule with fluid and steroid), then manipulation under anaesthesia or arthroscopic capsular release. There is good evidence that adding hydrodilatation to physiotherapy improves outcomes in resistant disease.
Choosing surgery: The UK FROST trial showed manipulation, arthroscopic release, and structured physiotherapy with injection give similar shoulder scores at one year, so the decision rests on risk and cost. In a diabetic, who often has resistant disease, I would favour a controlled arthroscopic capsular release of the rotator interval and capsule over a forceful manipulation, which risks fracture, dislocation and cuff injury - particularly important in diabetic or osteoporotic bone.
Aftercare: Whatever is done must be followed by immediate, intensive physiotherapy to hold the gains, and I would counsel him that recovery may be slower and less complete because of his diabetes.
Exam Points
Loss of passive external rotation with the arm at the side is the key examination finding and the most tested discriminator.
No scan makes the diagnosis. Radiographs are usually normal and are taken to exclude osteoarthritis and a locked posterior dislocation.
The strongest risk factor; diabetic disease is often bilateral, more resistant, and more likely to need surgery. Check a glucose.
UK FROST: manipulation, capsular release, and physiotherapy with injection give similar one-year scores - choose by risk and cost.
Injection helps most in the painful freezing stage; stretching, hydrodilatation and release target the stiff frozen stage.
Manipulation in osteoporotic or diabetic bone risks humeral fracture - prefer a controlled arthroscopic release.
Guidelines, Registries and Global Practice
- Diagnosis is consistently clinical. Systematic reviews of clinical practice guidelines for shoulder disorders agree that the initial assessment rests on history and examination, that MRI is usually not needed early, and that radiographs are used mainly to exclude other causes. The international (ISAKOS) terminology distinguishes primary frozen shoulder (idiopathic) from a secondary stiff shoulder (known cause).
- Conservative care first, side by side. Guidance from bodies such as the AAOS (US), BOA/BESS (UK), and equivalent European groups converges on the same ladder: education, analgesia, an early intra-articular steroid injection, and stretching physiotherapy, with hydrodilatation, manipulation, and arthroscopic capsular release reserved for resistant disease.
- Where guidance differs is mainly the threshold and timing for escalating to a procedure and the relative emphasis on hydrodilatation versus manipulation versus release - reflecting local resources and expertise rather than disagreement about the underlying disease.
- Best randomised evidence (UK FROST) shows the secondary-care options converge by one year, so many systems favour the least invasive, most cost-effective route, with surgery reserved for selected patients - especially the more resistant diabetic shoulder.
- Global practice variation largely reflects access (availability of image-guided injection, theatre time, and arthroscopy) rather than differences in the principles of stage-matched, escalating care.
Diagnosis
- Clinical diagnosis - painful, progressive, GLOBAL loss of movement
- Loss of both active AND passive range
- Loss of passive external rotation with arm at side - the signature sign
- Radiograph usually normal; taken to exclude other causes
Pathology and Risk
- Capsular inflammation then fibrosis and contracture
- Rotator interval and coracohumeral ligament hit first (external rotation lost first)
- Myofibroblast-driven contracture - overlap with Dupuytren disease
- Diabetes is the strongest risk factor - often bilateral and resistant
Treatment Ladder
- Education, analgesia/NSAIDs, reassurance (usually self-limiting)
- Early intra-articular steroid injection in the painful freezing stage
- Gentle stretching physiotherapy; hydrodilatation if resistant
- Manipulation under anaesthesia or arthroscopic capsular release for refractory disease
Red Flags and Pitfalls
- Preserved passive external rotation - reconsider the diagnosis
- Lost external rotation after seizure/shock - exclude locked posterior dislocation (axillary view)
- Manipulation in osteoporotic/diabetic bone risks humeral fracture
- UK FROST: treatments converge at 1 year - choose by risk and cost; physiotherapy mandatory after any procedure