Red flags for knee conditions

Prior to referral consider / screen to exclude:

Key Clinical Observations of concern:

  • Hot / red / swollen joint with raised body temperature  (raised inflammatory markers)
  • Septic/Unwell
  • Rapidly worsening deformity
  • Neuro-vascular compromise
  • Weight Loss
  • Continuous pain, including at night and when not weight bearing
  • Unable to walk or move knee
Urgent knee referral

Patients with any of the following suspected should be sent to A&E:

  • Fracture, or  knee dislocation
  • Quadriceps/Patella Tendon Rupture
  • Suspected Infection


Urgent appointments can be made for patients at Fracture/ Trauma Clinic for:

  • On- going infection
  • Locked knee
  • Recent ligament rupture
  • Large effusion/haemathrosis
  • Trauma suspected soft tissue damage
  • Traumatic patella dislocation


Urgent appointments can be made in elective Orthopaedic/ Rheumatology/Pain Clinics for patients with:

  • Rapidly worsening symptoms
  • Confirmed presence of cancer on imaging
  • Constant unrelenting pain / especially unrelenting night pain in presence of cancer
  • Progressive or significant neurological loss suggestive of acute peripheral nerve compression
GP / Primary Clinician

Consider diagnosis (discuss within peer review)

  • Consider possible fracture especially where trauma, large effusion / haemarthrosis.
  • Consider emergency/urgent referral to acute knee clinic if recent significant trauma.
  • Consider neurological cause.


  • Cruciate ligament injury ACL/PCL.
  • Postero-lateral corner.
  • Cruciate ligament and meniscal injury (see meniscal pathway).
  • Cruciate and collateral ligaments.
  • Chondral/Osteochondral/loose bodies.
  • Patella dislocation.



  • X-ray should not delay referral to acute knee clinic.
  • X-ray is recommended for instability.
  • X-ray Knee AP and lateral views and Skyline views where Patello-femoral joint involvement.
  • MRI not routinely indicated.
  • Consider guidelines in previous section.
  • Assessment / Diagnosis/ Detailed advice/ Lifestyle advice.
  • Acute injury management as appropriate.
  • Exercise to improve strength and functional stability.
  • Adaption of sporting activities if appropriate.
  • If not responding consider referral to Interface Team.
Interface Team
  • Review previous assessment, diagnosis and management .
  • Specifically review conservative treatment / Physiotherapy
  • Detailed advice / lifestyle advice.
  • Referral to Surgeon for opinion if fits criteria.
  • Referral to GP for advice re: analgesia.


  • X-ray recommended for instability.
  • X-ray Knee AP and lateral views and Skyline views where Patello-femoral joint involvement.
  • MRI as a second line investigation.
  • MRI is not a surgical prerequisite.


Surgical Criteria

No referrals to secondary care unless:

  • X-ray undertaken prior to referral


  • Patient has recurrent symptomatic instability confirmed at Interface


  • Patient has adhered to 3-6 months of conservative management and rehabilitation without improvement


  • Health Care Professional has discussed surgery with the patient who has confirmed they want explore surgery


  • General Health including fitness for anaesthesia has been considered and believed adequate to proceed to potential surgical intervention and it is believed that the patient is likely to derive quality of life benefits from surgery

Surgical reconstruction (arthroscopic or open) of ACL, PLC, PCL, MCL, LCL, - recovery period 6 weeks to drive 9-12 months to full recovery.