Adhesive Capsulitis (Frozen Shoulder)

🧬 Pathophysiology (What’s actually happening?)

• Early phase = synovitis: low-grade inflammatory change within the glenohumeral capsule → pain (often nocturnal) and protective muscle spasm.
• Progression = capsular fibrosis + contracture: fibroblast proliferation and collagen deposition (especially the rotator interval and coracohumeral ligament) → true mechanical loss of joint volume.
• “Capsular pattern”: external rotation becomes most restricted first because the contracted anterior capsule/coracohumeral ligament “locks” ER early.
• Diabetes link: advanced glycation end-products (AGEs) cross-link collagen → stiffer capsule, slower remodelling, often more bilateral and more persistent symptoms.

⏳ Natural History: the 3 phases (practical table)

🧠 Examination: what to look for (and what traps juniors fall into)

• Active = passive restriction in a similar pattern (this is the signature).
• External rotation is usually the most limited (compare both sides with elbows tucked in).
• Watch for scapulothoracic substitution (patient “cheats” by hiking the shoulder blade to fake overhead movement).
• Palpation is often non-specific; focal tenderness over the greater tuberosity points you more toward rotator cuff pathology.
• Check neck, neurology, and distal joints: referred pain and cervical radiculopathy can mimic shoulder disease.

🚩 Red flags (don’t miss these)

• Hot, red, systemically unwell → consider septic arthritis (urgent same-day assessment).
• Acute severe pain after trauma or deformity → dislocation/fracture (urgent imaging).
• Unexplained weight loss, night sweats, history of malignancy → consider sinister pathology.
• Neurological deficit (true weakness, dermatomal sensory loss) → consider cervical spine/nerve root issue.
• Rapid onset severe pain + swelling + allodynia after injury → consider CRPS (early recognition matters).

🧩 Differentiating from common look-alikes (quick heuristics)

• Rotator cuff tendinopathy/tear: painful arc, weakness; passive ROM often relatively preserved early.
• Subacromial impingement: pain with overhead activity; night pain possible, but global capsular restriction is less typical.
• Glenohumeral OA: older age, crepitus, reduced ROM with X-ray changes.
• Cervical radiculopathy: neck pain, paraesthesia, symptoms reproduced with neck manoeuvres; shoulder passive ROM may be near normal.

🧪 Investigations (UK practical approach)

• Usually clinical; the purpose of tests is to exclude alternative diagnoses.
• X-ray if atypical features, trauma, older age, or failure to progress → look for OA, calcific tendinopathy, fracture, dislocation.
• Bloods only if systemic features or inflammatory differential: FBC, CRP/ESR (PMR, infection, inflammatory arthritis).
• US/MRI are not routine; consider if significant weakness suggests cuff tear, or if diagnostic uncertainty persists.

🧭 Management: a stage-based, primary care–friendly pathway

• Step 1: Explain + set expectations: this is a capsular tightening process; recovery can be slow, and “forcing it” often backfires early.
• Step 2: Analgesia ladder (tailor to comorbidity):
  • Paracetamol regularly if safe.
  • NSAID (topical or oral) if appropriate; add gastroprotection where indicated.
  • Short course of stronger analgesia only if pain is blocking sleep/rehab (review frequently).
• Step 3: Physiotherapy:
  • Freezing (painful): gentle, pain-limited mobility + posture/scapular control; avoid aggressive stretching that inflames the capsule.
  • Frozen/thawing: progressive capsular stretching + strengthening of rotator cuff/scapular stabilisers.
• Step 4: Injection (best early):
  • Intra-articular corticosteroid can meaningfully reduce pain and improve ROM in the early “freezing” phase, helping patients engage with physio.
  • Diabetes counselling: warn about transient hyperglycaemia for a few days; advise more frequent glucose checks and a plan with their diabetes team if needed.
• Step 5: If persistent functional limitation:
  • Hydrodilatation (distension) may help some patients by mechanically expanding capsule volume, usually combined with immediate physio.
  • Referral to MSK/orthopaedics if severe restriction persists despite a good trial of conservative care.

🧘 Home exercise examples (simple, safe starters)

• Pendulum swings (pain-limited): lean forward, let arm hang, small circles.
• Table slide: hand on cloth on table, slide forward to gentle flexion.
• External rotation with stick: elbow tucked, use stick to gently rotate forearm outward (stop before sharp pain).
• Cross-body stretch: bring arm across chest to gentle posterior capsule stretch.
• Rule of thumb: discomfort is acceptable; sharp pain that lingers for hours suggests you’ve overdone it—dial back intensity.

🛠️ Procedural options (what to tell patients, realistically)

• MUA (Manipulation Under Anaesthesia): can rapidly improve ROM but carries risks (fracture, dislocation, cuff injury); outcomes are best with immediate structured physio afterwards.
• Arthroscopic capsular release: targeted release of contracted capsule; considered when prolonged symptoms persist despite non-operative care, particularly if function is severely impaired.
• Choice is individual: symptom phase, diabetes, occupational needs, and response to injection/physio all influence timing and benefit.

🧑‍⚕️ When to refer (useful thresholds)

• Urgent/same-day: red flags (infection, acute trauma/dislocation, neuro deficit).
• Routine MSK/physio: suspected frozen shoulder with functional impact (early referral helps).
• Specialist opinion: persistent significant restriction impacting ADLs after a structured trial of conservative management (often ~6–12 weeks), or earlier if the diagnosis is uncertain.

🧠 Stroke/neurology link (hemiparetic shoulder vs adhesive capsulitis)

• Post-stroke shoulder pain is multifactorial: subluxation, spasticity, rotator cuff pathology, CRPS, and secondary frozen shoulder can overlap.
• Key prevention: safe handling, positioning, supported arm, early guided ROM, and avoiding traction injuries during transfers.
• If stiffness becomes global with marked passive restriction, treat as possible adhesive capsulitis—pain control + gentle ROM early can prevent severe contracture.

🧠 Extra Teaching Pearls

• External rotation is the canary: if ER is markedly reduced compared with the other side, think capsular contracture early.
• Pain dominates early, stiffness dominates later—so match your intervention to the phase.
• Injection buys a window: the goal is not just analgesia; it’s enabling rehab when pain is the barrier.

Case examples (continued)

• 🏃‍♂️ Case 4 – Age 44: Recreational tennis player with 3 months of progressive night pain and difficulty fastening a bra/doing back-pocket movements. Marked loss of external rotation with equal limitation active/passive. Diagnosis: Early “freezing” adhesive capsulitis. Management: Education + sleep positioning, regular analgesia, early image-guided intra-articular steroid, then gentle physio. Teaching point: Early steroid is most useful when pain is the dominant symptom and stiffness is emerging.
• 🛌 Case 5 – Age 61: Worsening stiffness over 9 months, minimal pain now but cannot reach overhead cupboards or wash hair. X-ray normal. Diagnosis: “Frozen” phase adhesive capsulitis. Management: Structured stretching programme + strengthening; consider hydrodilatation if progress stalls. Teaching point: In the stiff phase, inflammation is less prominent—rehab tends to be the main driver of recovery.
• 🩸 Case 6 – Age 55: Type 1 diabetic with bilateral shoulder stiffness, poor sleep, and very slow improvement after standard physio. Diagnosis: Diabetic-associated adhesive capsulitis (often more refractory). Management: Realistic timelines, optimise glycaemia, consider staged injections/hydrodilatation, early specialist input if severe disability. Teaching point: Diabetes increases risk of bilateral disease and slows capsular remodelling—expect a longer course.

🌟 Mini-algorithm: Night pain + global passive restriction (esp ER) → exclude red flags & arthritis (X-ray if needed) → treat pain (early steroid if freezing) → phase-appropriate physio → consider hydrodilatation → refer for MUA/arthroscopic release if persistent severe functional limitation.