Knee / Leg injuries


History - nature of injury, e.g.. direct, indirect, rotational, presence of locking, giving way. Previous knee problems.

Examination - look, e.g.. wasting, deformity, swelling, bruising.

Feel - effusion, localise tenderness, check stability, popliteal swelling?

Move - check range, exclude locking by comparing extension on both sides - McMurray's test.

X-ray - For AP & Lat views see Ottawa Knee rules below. Additional views should include skyline view for patellar problems and tunnel view for intercondylar area (e.g. loose bodies)

Ottawa knee rule

These rules safely reduce need for imaging [Bandolier]

A knee X-ray series is only required for knee injury patients with any of these findings:

  • Age ≥ 55
  • Isolated tenderness of the patella (no bone tenderness of the knee other than the patella)
  • Tenderness at the head of the fibula
  • Inability to flex to 90°
  • Inability to bear weight both immediately and in the ED
    (4 steps; unable to transfer weight twice onto each lower limb regardless of limping)


Evidence for aspiration to improve symptoms ? [Bestbets]

Indications are: A) Tense haemarthrosis and B)Diagnostic uncertainty

Large effusion or haemarthrosis

  • Aspirate under full aseptic conditions, unless immediate referral or surgery intended because of severity of injury
  • If frank blood in the joint:
    • Immobilise in POP knee backslab and refer to Fracture Clinic (CUH referral form)
    • Refer to senior ED staff or on-call Orthopaedic Team
  • There is no evidence to support early MRI in acute traumatic knee haemarthoses with normal x-rays [Bestbets]

Locked knee

The knee will flex but will not fully extend. Refer to the on-call Orthopaedic Team (CUH referral form).

Collateral ligament tear

Tenderness and pain on stressing the ligament. If there is definite laxity and marked bruising/swelling obtain an opinion from EM Duty Doc. Complete ligament rupture can be masked by muscle spasm. If little laxity or pain is evident, apply tubigrip and refer to the ED physiotherapist.

Possible meniscal tear

If not locked, apply a double tubigrip and provide crutches. Refer ED physio clinic.

Possible torn cruciate ligaments.

Rest, crutches, physiotherapy referal and GP follow up. ACL rupture patients are NOT routinely refered to the fracture clinic or orthopaedic follow up as conservative management gives similar functional results to (early or late) surgery [BMJ 2013] Ref. These patients should NOT be referred to the ED clinic.

Loose bodies

If symptomatic refer to the orthopaedic clinic.

Anterior knee pain (chondromalacia patellae)

Please refer to the physiotherapy clinic and GP. Do NOT refer to the ED clinic.

Soft tissue knee problems of uncertain cause - refer to ED physiotherapist.

Knee dislocations

Check distal circulation. Refer to the on-call Orthopaedic Team.

Distal femoral and upper tibial fractures

(including osteochondral)- refer to the on-call Orthopaedic Team.

Patellar fractures

Patellar fracture lateral view
  • If undisplaced apply POP backslab and refer to the Fracture Clinic (CUH referral form)
  • If displaced, refer to the on-call Orthopaedic Team
  • Most need internal fixation as quads tone distracts the fragments

Dislocated patella

Dislocated patella
  • Usually reduced before presentation - if not, reduce by extending hip (Entonox)
  • X-ray to exclude fracture
  • If first episode, treat conservatively in preference to surgry [BestBets]
  • If first episode, apply cricket bat splint in preference to POP cylinder [Bestbets]
  • Refer to the Fracture Clinic (CUH referral form)
  • Consider prophylactic anticoagulation (LMWH) if high risk of VTE or prior DVT.[BestBets]

Summary of referral pattern for acutely injured knee:

  • Referral to on-call orthopaedic team - all fractures except undisplaced fractured patella, locked knee, dislocated knee
  • Referral to Fracture clinic - dislocated patella, undisplaced fractured patella (CUH referral form)
  • Referral to physiotherapist or ED Clinic - ? meniscal tears, ? cruciate tears, collateral ligament sprain, soft tissue problems of uncertain cause

Osteochondritis Dessicans

Please see anterior knee pain section.

Fractures of the tibial shaft

  • Beware compartment syndrome in all (even apparently simple fractures). Record neurovascular status. 
  • Analgesia. 
  • Above knee POP. 
  • Refer to the on-call Orthopaedic Team

Fractures shaft of fibula

  • Ensure no ankle diastasis by requesting ankle X-rays
  • Check common peroneal nerve
  • If no other abnormality bandage or plaster for comfort and refer to the Fracture Clinic (CUH referral form)


In patients immobilised in leg casts:

  • Consider prophylactic anticoagulation (LMWH) if high risk of VTE or prior DVT.[BestBets]
  • CUH EM and Orthpaedic divisions have (Feb 2013) reviewed the literature (including the 2012 Oct CEM guideline). Prophylactic anticoagualtion is not required those pateints discharged in a backslab


Frobell RB etl al. Treatment for acute anterior cruciate ligament tear: five year outcome of randomised trial. BMJ 2013;346:f232

Content by Dr Íomhar O' Sullivan 14/03/2004.  Reviewed by Dr ÍOS 17/05/2005, 22/05/2006, 01/02/2007.   Last review Dr IOS 21/06/21.