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Knee injury
Twisting or direct knee injury — Ottawa knee rule, spot the ACL and locked knee.
Typical consult⏱ 15–20 min
Investigations🔬 X-ray only if Ottawa positive
Usual outcome💊 Analgesia + PRICE + crutches
0–5Red flags + history5–12Examine12–17Decide17–24Treat + explain24–30Safety-net + document
1Rule out first — red flags
| If you find… | …then |
|---|---|
| Locked knee (can’t fully straighten) | Displaced meniscal tear — ortho referral (urgent) |
| Unable to straight-leg raise | Extensor mechanism rupture / patella fracture — X-ray, ortho |
| Neurovascular deficit after high-energy injury | Possible knee dislocation (popliteal artery) — ED now |
| Hot swollen knee with no/minor injury, febrile | Septic arthritis — aspirate, ED/ortho |
| Rapid swelling within 2 h | Haemarthrosis — ACL tear or fracture likely |
2Focused history
3Focused examination
4Decide — investigate only if it changes the plan
Ottawa knee rule
- Age 55 or over
- Isolated tenderness of the patella
- Tenderness of the fibular head
- Unable to flex knee to 90°
- Unable to weight-bear 4 steps both immediately and in clinic
Any one positive → knee X-ray. All negative → no X-ray needed.
| Investigation | Only if… |
|---|---|
| Knee X-ray (AP + lateral) | Only if Ottawa knee rule positive |
| Lipohaemarthrosis on lateral X-ray | Fat–fluid level = intra-articular fracture → ortho |
5Treat & send home
Management & advice
- PRICE for 48–72 h; avoid HARM
- Weight-bear as able; crutches if painful
- Hinged brace / tubigrip only if it helps comfort (local practice)
- Early quadriceps exercises (static quads, straight-leg raises)
Refer / follow-up
- Suspected ACL tear (pop, rapid swelling, instability) → soft-tissue knee clinic / fracture clinic per local pathway
- Fracture → fracture clinic
- Locked knee → orthopaedics (urgent)
- Others → physiotherapy if not improving at 2–3 weeks
℞
Discharge prescription (TTO)Typical adult doses — check the BNF/BNFc, allergies, renal function, pregnancy and interactions.
| Drug | Dose | Duration / notes |
|---|---|---|
| Paracetamol | 1 g every 4–6 hours, max 4 g in 24 h (reduce if under 50 kg or liver risk) | As needed |
| Ibuprofen 5% gel (topical NSAID) | Apply thinly up to 3 times a day | Up to 1–2 weeks |
| Ibuprofen | 400 mg three times a day with food | 3–5 days. Avoid: NSAID-sensitive asthma, GI bleed/ulcer, renal impairment, anticoagulants, heart failure, pregnancy |
6Safety-net
Say it like this
There’s no sign of a fracture. It’s most likely a soft-tissue injury. Rest it for a couple of days, ice and raise it, then start moving it gently. If it keeps giving way we’ll get you seen in the knee clinic. Come back straight away if it becomes hot and very swollen, you feel feverish, it locks, or you get calf pain.
Come back / call 111 — or 999 if severe — if:
- Knee becomes hot, red and very swollen, or you feel feverish
- Calf pain or swelling, or breathlessness
- Knee locks and you can’t straighten it
- Foot becomes cold, pale or numb
7Patient leaflets — scan & go
Official NHS pages. Ask the patient to scan the code with their phone camera, or tap “Show to patient” to make it full screen.
8Document
Knee injury — clinic note
A structure to document efficiently. It is not a completeness check — use your trust’s system and your clinical judgement.
URGENT CARE — KNEE INJURY
PRESENTING COMPLAINT:
HISTORY
Mechanism: twisting with foot planted / direct blow / hyperextension:
Pop, immediate swelling (< 2 h) or delayed (overnight)?:
Weight-bearing now? Giving way? Locking or catching?:
Previous knee problems:
Sport, job, driving:
PMH: anticoagulants, gout, diabetes:
RED FLAGS (record present / absent)
[ ] Locked knee (can’t fully straighten)
[ ] Unable to straight-leg raise
[ ] Neurovascular deficit after high-energy injury
[ ] Hot swollen knee with no/minor injury, febrile
[ ] Rapid swelling within 2 h
PMH:
DRUG HISTORY:
ALLERGIES:
SOCIAL (job / who is at home / driving):
OBSERVATIONS: RR SpO2 HR BP Temp (NEWS2 )
EXAMINATION
Look: effusion, bruising, deformity; walk:
Feel: patella, fibular head, joint lines, tibial tuberosity:
Move: active flexion to 90°, full extension, straight-leg raise:
Effusion (patellar tap / sweep):
Stress: Lachman, anterior drawer, collateral ligaments at 0° and 30°:
Distal pulses and sensation:
DECISION RULE — Ottawa knee rule: result ______
INVESTIGATIONS: none required / Knee X-ray (AP + lateral), Lipohaemarthrosis on lateral X-ray — result:
IMPRESSION:
PLAN
Treatment / TTO (drug, dose, duration):
Advice given:
Leaflet given (QR / printed): Knee pain, Sprains and strains
Follow-up / referral:
SAFETY-NETTING (told to return / call 111 / 999 if):
- Knee becomes hot, red and very swollen, or you feel feverish
- Calf pain or swelling, or breathlessness
- Knee locks and you can’t straighten it
- Foot becomes cold, pale or numb
Patient understands and agrees with the plan: Y / N
Seen by: Grade: Date/Time:
✓Guidelines
Doses are typical adult doses drawn from the guidance above. Always check the current BNF/BNFc and your local antimicrobial policy.
More injuries & musculoskeletal
Ankle & foot injuryTwisted ankle or foot — Ottawa rules decide the X-ray.Wrist injury & scaphoidFall on the outstretched hand — distal radius vs scaphoid.Hand & finger injuryBoxer’s fracture, mallet finger, crush injuries and the hand you must not miss.Shoulder & collarbone injuryCollarbone fractures, ACJ injuries and the dislocated shoulder.