Reasoning GP · Algorithm · 1-page summary
Ankle pain in adults
For: adults with ankle pain, after an injury or without one, in primary care. Not for: children (use the limping child algorithm); ankle swelling without pain (use the ankle swelling algorithm).
Core rule: apply the Ottawa ankle and foot rules after every injury, do the calf-squeeze (Simmonds–Thompson) test on every posterior heel pain or lost push-off, and treat a hot, swollen ankle as septic arthritis until excluded.
0Stop — call 999 now
- Deformed ankle, open injury or neurovascular compromise (pallor, cold foot, absent pulse, paraesthesia) → 999 / ED for urgent reduction.
- Possible PE: chest pain, dyspnoea, haemoptysis, syncope or unexplained tachycardia → Same-day hospital PE assessment, immediately; collapsed, severely breathless or haemodynamically unstable → 999
1Triage — Ottawa rules, age >5, reliable examination
| Finding | Action |
|---|---|
| Ottawa ankle | Malleolar pain + bony tenderness at the posterior edge or tip of either malleolus (lower 6 cm), or cannot take 4 weight-bearing steps both immediately and at assessment → X-ray via local pathway |
| Ottawa foot | Midfoot pain + tenderness at 5th metatarsal base or navicular, or the 4-step test → X-ray |
| Rule unreliable | Intoxication, neuropathy, distracting injuries, altered mental state, suspected stress or pathological fracture, or concern remains → X-ray anyway |
2Screen — serious causes
- Achilles rupture: sudden "kick", absent plantar flexion on calf squeeze (a gap may be absent) → Same-day orthopaedics/ED; immobilise in plantar flexion, avoid dorsiflexion.
- Hot, swollen ankle with severe pain or restricted movement → septic until excluded → Same-day hospital. Gout and sepsis can coexist.
- Warm, swollen foot or ankle with diabetes or neuropathy (possible Charcot, may be painless) → MDT foot service ≤1 working day; non-weight-bearing; weight-bearing X-ray, MRI if normal but still suspected (NG19).
- New unilateral calf swelling, pain, warmth: two-level Wells (NG158): ≥2 → proximal leg-vein USS ≤4 h, or D-dimer + interim anticoagulation + USS ≤24 h; ≤1 → D-dimer, USS if positive.
- Widened mortise (syndesmosis), osteochondral defect, peroneal tendon dislocation, or stress fracture at a high-risk site (navicular, talus, anterior tibial cortex, 5th metatarsal base) → Urgent orthopaedics.
- Confirmed fracture: fracture clinic ≤72 h; VTE risk via local pathway.
3Assess
☐ Skin, deformity, pulses, sensation ☐ Malleoli, 5th metatarsal base, navicular, proximal fibula (Maisonneuve), syndesmosis ☐ Calf squeeze prone, compare sides ☐ Anterior drawer, talar tilt vs other side ☐ Gait, single-leg heel raise, "too many toes" ☐ Suspected infection: FBC, CRP, blood cultures, aspiration ☐ Urate during or after a flare; renal function before NSAID, colchicine or ULT
Not routine: imaging for OA or tendinopathy at presentation.
4Classify — only if blocks 0–2 are negative
- Lateral ligament sprain — inversion, ATFL tenderness; grade I stretch, II partial tear, III complete rupture.
- Achilles tendinopathy — heel pain worse mornings and after exercise, thickened tendon, calf squeeze normal. Ask about fluoroquinolones.
- Gout — acute hot, red, swollen ankle or 1st MTP. Urate <360 μmol/L in a flare → repeat ≥2 weeks after it settles.
- Tibialis posterior — medial pain, flat arch, "too many toes". Peroneal tendon — lateral pain after a sprain, snap or clunk.
- Ankle OA — insidious, stiffness <30 min, previous fracture; diagnosed clinically.
- Uncertain — not better at 4–6 weeks → re-examine, X-ray if not done, consider imaging (peroneal tendon, osteochondral).
5Treat today — doses: NICE/SPC, BNF, local formulary
- Sprain I–II: protection, relative rest, ice, compression, elevation; early progressive weight-bearing; lace-up brace for significant sprains or sport. Short NSAID may be considered, not routinely.
- Acute gout (sepsis excluded): offer NSAID, colchicine or short oral steroid by comorbidity, renal function, interactions. Keep established ULT.
- Achilles tendinopathy: progressive tendon-loading programme over about 12 weeks. No steroid injection into or around the Achilles.
- Ankle OA: exercise, weight management; consider a topical NSAID. Not routinely paracetamol or weak opioids; no strong opioids.
6Refer routinely and review
- Physiotherapy: persistent, recurrent or unstable sprains; tendinopathy; tibialis posterior dysfunction; OA.
- Orthopaedics/MSK: tendinopathy not better after about 12 weeks of loading; OA limiting function despite conservative care; progressive flat foot.
- Rheumatology: inflammatory arthritis; gout refractory to ULT, tophi or stones.
- Gout at 4 weeks: urate; offer ULT for multiple or troublesome flares, CKD 3–5, diuretics, tophi or chronic gouty arthritis (discuss after a first); target <360 μmol/L.
7Never reassure by
- No palpable gap, or able to walk — Achilles rupture is still possible.
- A negative Ottawa rule when the examination is unreliable.
- Urate crystals or known gout in a hot joint — infection can coexist.
- A normal urate during a flare, or a normal early X-ray in a suspected stress fracture.
- "Another sprain" — recurrent giving way needs rehabilitation, not repeated rest.
- A calf squeeze to rule out DVT.
8Safety-net — say it, then document it
999 “Call 999 if you get chest pain, breathlessness, cough up blood, collapse or a racing heart, or if your foot goes pale, cold, numb or tingly.”
Same day: “Go to A&E today if you feel a sudden snap at the back of the ankle, cannot push off, or can no longer put weight on the foot. Contact us or NHS 111 straight away for a fever with a hot, swollen ankle, or new calf swelling or pain. Come back if not improving in 1–2 weeks.”
✓Safe to leave primary care only if — all five, documented
No block 0–2 row applies
Ottawa rules and neurovascular status recorded
Calf squeeze done when heel pain or lost push-off
Diagnosis named, or uncertainty → imaging or specialist
Review date and safety-net given and documented
Summary of the full Reasoning GP ankle pain algorithm, which holds the history, differential, rehabilitation and evidence. Sources: NICE NG38, NG219 (gout), NG158 (VTE diagnosis), NG89 (VTE prevention), NG226 (osteoarthritis), Ottawa rules, BOA standards, MHRA Drug Safety Updates (fluoroquinolones). Clinical reference — follow local pathways and check doses: NICE/SPC, BNF.