Leg Pain
Leg pain is a symptom arising from musculoskeletal, vascular, neurological, or other causes, ranging from benign muscle cramps to limb-threatening conditions such as peripheral arterial disease or deep vein thrombosis.
Murtagh Diagnostic Strategy
| Category | Diagnosis | Key Discriminator | Cantonese Question / Finding | Probability |
|---|---|---|---|---|
| Probability Diagnosis | Musculoskeletal strain / soft tissue injury | Acute onset after exertion, localised tenderness, no vascular/neuro deficit | 「最近有冇做運動或者扭親？」 | ~30% |
| Osteoarthritis (hip/knee) | Pain on first step, worse with activity, age > 50, bony crepitus | 「行第一步會唔會痛？上落樓梯點？」 | ~20% | |
| Chronic venous insufficiency / varicose veins [5] | Aching/heaviness worse with standing, relieved by elevation; visible varicosities, skin pigmentation | 「企得耐會唔會隻腳脹住痛？抬高隻腳好啲？」 | ~10% | |
| Serious Not To Miss | Deep vein thrombosis (DVT) [4] | Unilateral swelling, warmth, risk factors (immobility, OCP, malignancy); Wells score | 「隻腳有冇腫咗？最近有冇坐長途機/做手術？」 | ~3% |
| Acute limb ischaemia [1] | Sudden 6Ps (pain, pallor, pulseless, perishing cold, paraesthesia, paralysis); < 2 weeks | 「隻腳突然變白變凍、冇脈搏、痺或者郁唔到？」 | ~1% | |
| Bone metastasis / primary bone tumour | Night pain, weight loss, constant progressive pain, hx of cancer | 「夜晚瞓覺會唔會痛醒？體重有冇輕咗？」 | < 1% | |
| Cauda equina syndrome [3] | Bilateral leg pain/weakness, saddle anaesthesia, urinary retention | 「會陰位有冇痺？大小便有冇失禁？」 | < 1% | |
| Pitfalls | Lumbar disc herniation / sciatica [3][6] | Pain radiating from back to leg (dermatomal), positive SLR, worsened by coughing/Valsalva | 「有冇痛由腰伸落去腳趾？咳嗽會唔會痛啲？」 | ~10% |
| Peripheral arterial disease (intermittent claudication) [2] | Reproducible calf pain after fixed walking distance, relieved by standing still; absent pedal pulses | 「行幾遠會開始痛？企定定幾耐會好？」 | ~5% | |
| Spinal stenosis (neurogenic claudication) [2] | Variable claudication distance, relieved by bending forward ("shopping trolley sign"), paraesthesia | 「推住架手推車行會唔會舒服啲？」 | ~4% | |
| Cellulitis | Localised erythema, warmth, tenderness, fever; skin break/wound as portal of entry | 「隻腳有冇紅腫熱痛？有冇損傷或者傷口？」 | ~3% | |
| Baker's cyst rupture | Sudden calf pain/swelling in patient with known knee arthritis | 「膝頭之前有冇關節炎？係咪突然間小腿腫晒？」 | ~2% | |
| Masquerades | Depression (somatisation) [8] | Multiple somatic symptoms, low mood, sleep/appetite disturbance, disproportionate worry | 「心情點？瞓得好唔好？食嘢點？」 | ~10% |
| Diabetic peripheral neuropathy [7] | Glove-and-stocking burning/numbness, known DM, reduced monofilament/vibration sense | 「你有冇糖尿？隻腳底有冇痺或者好似踩住棉花咁？」 | ~5% | |
| Drug-induced myopathy (statins) | Diffuse muscle ache after starting statin, raised CK | 「有冇食降膽固醇藥？開始食之後隻腳有冇痠痛？」 | ~2% | |
| Trying to Tell Me Something? | Psychosocial stress / fear of serious disease / work-related | Worried about amputation (family member had it), job loss, inability to care for family | 「有冇嘢令你特別擔心？屋企或者工作有冇壓力？」 | ~10% |
| Time | Task | Cantonese Key Phrases | Why It Scores Marks |
|---|---|---|---|
| 0:00–0:30 | Greeting, rapport, open question | 「你好，我係今日嘅醫生，點稱呼你？」「今日有咩唔舒服想同我講？」 | Friendly opening; patient-centred start scores interpersonal marks |
| 0:30–2:00 | HPI: SOCRATES for leg pain, onset, site, character, radiation, severity, aggravating/relieving, timeline | 「隻腳邊度痛？」「痛咗幾耐？」「係點樣痛法？（痺、攣、刺、脹）」「行路會唔會痛啲？休息有冇好啲？」「有冇條件會令到痛啲或者好啲？」 | Symptom analysis is the bulk of HPI marks |
| 2:00–2:45 | Red flags: acute ischaemia (6Ps), DVT, cauda equina | 「隻腳有冇變白/變藍/凍咗？」「有冇腫咗？」「有冇覺得隻腳冇力、痺或者郁唔到？」「大小便有冇問題？」 | "Must not miss" serious disorders |
| 2:45–3:30 | Targeted Hx: vascular RFs, joint/MSK, neuro, back pain | 「你有冇糖尿/高血壓/膽固醇高/食煙？」「有冇腰痛或者痛落去腳？」「關節有冇腫脹或者晨僵？」 | Differentiates MSK vs vascular vs neurogenic |
| 3:30–4:15 | PMHx, DHx, allergy, FHx, social Hx | 「之前有冇乜嘢大病或者做過手術？」「而家食緊咩藥？有冇藥物敏感？」「屋企人有冇類似嘅問題？」「你做咩工作？平時有冇做運動？有冇飲酒食煙？」 | Completeness of history |
| 4:15–5:00 | ICE + hidden agenda | 「你自己覺得咩原因引起呢？」(Ideas)「你最擔心啲咩？」(Concerns)「你嚟睇醫生最希望醫生幫你做啲咩？」(Expectations)「點解揀今日嚟睇？」(Hidden agenda: "Why today?") | ICE is a dedicated mark; hidden agenda uncovers the real RFC |
| 5:00–5:30 | Summarise back to patient | 「等我總結一下你講嘅嘢，睇下有冇遺漏…」 | Shows active listening, scores interpersonal marks |
| 5:30–6:00 | Brief plan, safety net, close | 「我會幫你安排檢查…如果隻腳突然變白、冇知覺或者郁唔到，要即刻去急症室。」「你有冇嘢想問？」 | Safe closure; safety-netting scores marks |
Hidden agenda tip: A patient with "leg pain" may actually be worried about cancer (bone mets), blood clot after travel, or peripheral artery disease because a relative had an amputation. Always ask 「點解揀今日嚟睇？有冇特別嘢令你擔心？」
| Domain | English Question | Cantonese Question | Why It Matters | If Positive Think Of |
|---|---|---|---|---|
| Site | Which part of the leg? Unilateral/bilateral? | 「邊隻腳？邊個位置痛？兩隻腳都有定係一隻？」 | Localises pathology; unilateral swelling → DVT | DVT, MSK injury, radiculopathy |
| Character | Cramping? Aching? Burning? Numbness? | 「係點樣痛法？攣住痛？脹住痛？痺痺哋？」 | Cramping on exertion → claudication; burning/numbness → neuropathy | PAD, neuropathy, spinal stenosis |
| Onset & duration | Sudden or gradual? How long? | 「係突然痛定慢慢開始？痛咗幾耐？」 | Sudden < 2wk → acute ischaemia/DVT; chronic → PAD/OA/neuropathy [1] | Acute limb ischaemia, DVT |
| Exacerbating | Walking? Standing? Rest? Going uphill/downhill? | 「行路會痛啲定係休息先痛？行幾遠先開始痛？」 | Claudication distance; vascular vs neurogenic claudication [2] | PAD (constant distance), spinal stenosis (variable distance, relieved by bending) |
| Relieving | Standing still? Sitting/bending? Elevation? | 「企定定會好啲定係要坐低彎腰先舒服啲？抬高隻腳有冇好啲？」 | Stand-still relief → vascular; bend-forward relief → neurogenic [2] | Spinal stenosis vs PAD |
| Radiation | Does pain go from back to leg? | 「有冇痛由腰背伸落去腳？」 | L4/5, L5/S1 radiculopathy → sciatica [3] | Disc prolapse, spinal stenosis |
| Swelling | One leg swollen? Both? | 「隻腳有冇腫？一隻定兩隻？」 | Unilateral oedema → DVT; bilateral → CCF, CVI [4] | DVT, CVI, lymphoedema |
| Colour/temp change | Leg turning white/blue/red? Cold? | 「隻腳有冇變色——變白、變藍或者變紅？凍唔凍？」 | White/cold → acute ischaemia (6Ps); red/warm → cellulitis/DVT [1] | Acute limb ischaemia, DVT, cellulitis |
| Neuro deficit | Weakness? Numbness? Bladder/bowel? | 「隻腳有冇冇力、痺？大小便有冇問題？」 | Cauda equina = emergency; foot drop → peroneal palsy/L5 | Cauda equina, disc prolapse, DM neuropathy |
| Vascular RFs | DM, HTN, smoking, HLD, AF, family | 「你有冇糖尿、高血壓、膽固醇高？食唔食煙？有冇心房顫動？」 | PAD risk stratification; AF → embolic source [1] | PAD, acute embolic ischaemia |
| DVT RFs | Recent travel/surgery/immobilisation? OCP? Cancer? Pregnancy? | 「最近有冇坐長途飛機/做手術/長時間唔郁？有冇食避孕藥？」 | Virchow's triad assessment [4] | DVT → PE |
| Joint symptoms | Morning stiffness? Locking? Giving way? | 「朝早起身有冇僵硬？行路有冇鎖住或者軟腳？」 | Morning stiffness > 30 min → inflammatory; mechanical → OA, meniscal | RA, OA, gout, knee sport injury |
| Back pain | Any low back pain? | 「有冇腰痛？」 | Referred/radicular leg pain from spine [3] | Disc herniation, spinal stenosis, spondylolisthesis |
| PMHx | Previous DVT/PE? DM? Cancer? | 「之前有冇試過腳腫/肺栓塞？有冇糖尿/癌症？」 | Recurrent VTE; DM neuropathy; bone mets | DVT, DM neuropathy, metastatic bone disease |
| Drug Hx | Statins (myalgia)? Anticoagulants? OCP? | 「有冇食降膽固醇藥？有冇食薄血藥或者避孕藥？」 | Statin-induced myalgia is a masquerade; OCP → DVT risk | Drug-induced myalgia, DVT |
| Social/Occupation | Standing job? Exercise level? | 「你返工要企好耐定係坐多？平時做咩運動？」 | Prolonged standing → CVI; athlete → sport injury | Varicose veins, muscle/tendon injury, stress fracture |
| Functional impact | Can you walk? Sleep affected? Work affected? | 「痛到有冇影響行路/瞓覺/返工？」 | Functional impact for biopsychosocial problem formulation | — |
| ICE | What do you think is causing it? What worries you most? What do you hope I can do? | 「你自己覺得咩原因？最擔心啲咩？最希望我幫到你咩？」 | Dedicated ICE marks | — |
Case Report Form Answer Builder
- CC: Leg pain × [duration], [uni/bilateral], [acute/chronic]
- HPI must include: SOCRATES, functional impact, aggravating/relieving factors (exercise vs rest), associated swelling/colour change/numbness/weakness, back pain/radiation, relevant risk factors (DM, smoking, immobilisation, OCP), relevant negatives (no bladder/bowel dysfunction, no fever)
- Common RFC examples for leg pain:
- "Worsening leg pain affecting daily walking and work"
- "Worried about blood clot after long-haul flight"
- "Concerned the leg pain may be caused by a serious condition (e.g. blood clot, poor circulation)"
- Phrasing tip: State ONE reason that explains why the patient came today. It may not be the symptom itself but the fear/functional limitation.
| Component | Example Wording |
|---|---|
| Ideas | "Patient thinks the pain may be due to poor blood circulation / slipped disc / old age" |
| Concerns | "Patient is worried about blood clot / amputation / cancer because a family member had similar problem" |
| Expectations | "Patient wants a blood test / X-ray / referral to specialist / reassurance that it is not serious" |
- Choose based on the stem's context. In a typical FM station with a middle-aged/elderly patient:
- If exercise-related calf pain with vascular RFs → Peripheral arterial disease (intermittent claudication)
- If unilateral swelling after immobilisation → DVT
- If back-to-leg radiation with neuro signs → Lumbar radiculopathy / disc herniation
- If chronic bilateral aching with varicosities → Chronic venous insufficiency
- If burning/numbness in DM patient → Diabetic peripheral neuropathy
- Minimum evidence: State 2–3 history features + 1 physical sign that support your diagnosis.
| DDx | One Key Discriminator |
|---|---|
| Peripheral arterial disease (intermittent claudication) | Fixed claudication distance, absent pedal pulses, vascular RFs |
| Lumbar disc herniation / sciatica | Dermatomal radiation from back, positive straight leg raise |
| Deep vein thrombosis | Unilateral swelling + warmth, immobilisation risk factor, elevated Wells score |
(Adjust based on your chosen most likely diagnosis — these three should be alternatives to it.)
| Domain | Problem |
|---|---|
| Biological | Uncontrolled DM / hypertension / smoking contributing to vascular disease |
| Psychological | Anxiety about amputation or cancer; fear of serious underlying disease |
| Social | Unable to work (standing/walking job); reduced mobility affecting ADLs and social activities; caregiver burden |
| Diagnosis/DDx | Best Supporting Physical Sign | How to Elicit It | Why It Supports This Diagnosis |
|---|---|---|---|
| PAD / Intermittent claudication | Absent or weak dorsalis pedis / posterior tibial pulse [2] | Palpate dorsalis pedis (lateral to extensor hallucis longus tendon) and posterior tibial (behind medial malleolus); compare bilaterally; use handheld Doppler if needed | Absent pulses indicate arterial insufficiency distal to the occlusion |
| DVT | Unilateral calf swelling (> 3 cm difference in calf circumference) [4] | Measure calf circumference 10 cm below tibial tuberosity bilaterally | Asymmetric swelling is the most reliable clinical sign; Homans' sign is unreliable |
| Lumbar disc herniation | Positive straight leg raise (SLR) test [3][6] | Patient supine, passively raise affected leg with knee extended; positive if radicular pain reproduced at < 60° | Stretches L5/S1 nerve roots; highly sensitive for lower lumbar disc herniation |
| Chronic venous insufficiency | Varicose veins with haemosiderin skin pigmentation at medial malleolus [5] | Inspect lower legs while patient standing; note tortuous dilated veins and brownish discolouration around gaiter area | Venous hypertension → RBC extravasation → haemosiderin deposition |
| Diabetic peripheral neuropathy | Reduced sensation to 10g monofilament [7] | Apply 10g monofilament to plantar surface of foot (1st, 3rd, 5th metatarsal heads, great toe); ask patient to report when felt | Loss of protective sensation confirms peripheral neuropathy in a known diabetic |
| Acute limb ischaemia | Absent pulse with pale, cold limb [1] | Palpate all LL pulses (femoral, popliteal, dorsalis pedis, posterior tibial); assess limb colour and temperature | 6Ps confirm acute ischaemia; absent pulse is the cardinal sign |
| Spinal stenosis | Reduced lumbar extension reproducing symptoms | Ask patient to extend lumbar spine; symptoms reproduced with extension, relieved with flexion | Extension narrows spinal canal, compressing neural elements |
| Cellulitis | Localised erythema with warmth and tenderness, well-demarcated border | Inspect and palpate affected area; mark the border of erythema with pen | In brief FM station, may be the only diagnosis with clear, visible sign |
Top Traps That Lose Marks
- Forgetting to ask about back pain — leg pain is commonly referred from the lumbar spine. Always ask about back pain and radiation.
- Missing DVT risk factors — immobilisation, recent surgery, OCP, malignancy, pregnancy. If you don't ask, you can't diagnose.
- Confusing vascular and neurogenic claudication — vascular: fixed distance, relieved standing still; neurogenic: variable distance, relieved by bending forward [2].
- Not checking ICE — dedicated marks. If you forget to ask "What are you worried about?", you lose easy marks.
- Diagnosing DVT without considering cellulitis and Baker's cyst — the DDx overlap is a favourite exam trap.
- Writing "musculoskeletal pain" without specifying — be specific: OA knee, muscle strain, stress fracture.
- Ignoring statin-induced myopathy — always check drug history.
- Missing cauda equina red flags — bilateral symptoms, bladder/bowel disturbance, saddle anaesthesia = immediate referral.
Must-Not-Miss Red Flags — Urgent Referral
- Acute limb ischaemia (6Ps): Pulseless, pale, perishing cold, painful, paraesthesia, paralysis → Emergency vascular referral [1]
- DVT with PE symptoms: Leg swelling + chest pain / dyspnoea / haemoptysis → Emergency A&E [4]
- Cauda equina syndrome: Bilateral leg weakness + saddle anaesthesia + urinary retention → Emergency spinal surgery referral [3]
- Suspected bone malignancy: Night pain, weight loss, constant pain, pathological fracture risk → Urgent orthopaedic / oncology referral
GC High-Yield Lecture Point: Lumbar disc herniation at L4/5 and L5/S1 are the most common levels. Physical examination includes straight leg raise test (SLR) — positive at < 60° reproduces radicular pain. Crossed SLR (raising the unaffected leg reproduces pain in the affected leg) is less sensitive but highly specific. [3][6]
GC High-Yield Lecture Point: For intermittent claudication, differentiate from neurogenic claudication: vascular claudication has a constant claudication distance and is relieved by standing still ("shop window to shop window"); neurogenic claudication has a variable claudication distance and is relieved by flexion ("park bench to park bench"). [2]
Safety-net line (for closing): 「如果隻腳突然變白、冇感覺、或者郁唔到，要即刻去急症室。如果痛咗越嚟越嚴重或者有新嘅症狀，記得返嚟覆診。」
High Yield Summary
What to ASK: SOCRATES for leg pain; back pain/radiation; swelling/colour/temperature change; walking distance and relief pattern; bladder/bowel symptoms; vascular RFs (DM, smoking, AF); DVT RFs (immobilisation, OCP, cancer); drug history (statins); ICE and "Why today?"
What to WRITE: Specific CC with laterality and duration; HPI with red-flag negatives documented; ONE main RFC reflecting the patient's real concern; ICE in their own words; most likely diagnosis with 2–3 supporting features; three DDx with discriminators; biopsychosocial problems; one physical sign with reasoning.
What NOT to MISS: Acute limb ischaemia (6Ps), DVT → PE, cauda equina syndrome, bone malignancy. Always ask about back-to-leg radiation. Always check ICE. Always palpate pedal pulses.
Active Recall - Family Medicine Clinical Test
[1] Senior notes: Maksim Surgery Notes.pdf (Acute limb ischaemia, p.168) [2] Senior notes: Ryan Ho Cardiology.pdf (Intermittent claudication and vascular vs neurogenic claudication, p.205) [3] GC Lecture slides: GC 226. Lumbar Spine Pathology_Part B.pdf (Physical Examination of back pain) [4] Senior notes: Block A - Leg swelling and chest pain_ deep vein thrombosis; pulmonary embolism; Thrombophilia.pdf (DVT clinical features, p.21); Ryan Ho Haemtology.pdf (VTE, p.131) [5] Lecture slides: Clinical Demonstration_Vascular.pdf (Venous examination, p.3); MBBS Final MB (Surgery) (Felix PY Lai).pdf (Varicose veins, p.949) [6] AOS material: AOS - Radiology.pdf (Sciatica case, p.32) [7] Senior notes: Ryan Ho Endocrine.pdf (Diabetic peripheral neuropathy, p.98); Maksim Medicine Notes.pdf (Diabetic foot, p.89) [8] Senior notes: Ryan Ho Psychiatry.pdf (Somatic symptom disorder, p.202)
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