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
Exclude red flags.

Consider diagnosis (discuss within peer review).


  • Referred pain from back or hips
  • Possible underlying PFJ OA (see separate OA pathway).
  • Patella Tendinopathy.
  • Hoffa’s Syndrome (Fat Pad Impingement ).
  • PFJ Lateral Compression Syndrome.
  • Biomechanical influences.
  • Impact high loading activities.


  • Optimal analgesia/ NSAIDS.
  • Advice and reassurance and Patient information
  • Modify activity/ reduce impact loading.
  • Supportive footwear with insoles and avoid high heels to reduce loading on anterior knee structures.
  • Discuss weight management and smoking cessation if appropriate.
  • Consider self-referral or refer to Physiotherapy.


  • X-ray not routinely indicated.
  • X-ray only for suspected Trauma, OA , infection, tumour, or inflammatory arthritis .
  • MR not routinely indicated.
  • Consider guidelines in previous section.
  • Assessment / Diagnosis/ reassurance.
  • Detailed advice and reassurance regarding condition / activity and lifestyle modification.
  • Combinations of appropriate multi-modal package of care e.g. stretching, exercise, manual therapy, rarely taping as part of functional restoration and adherence to exercise.

If not responding consider onward referral to Interface Team.


  • Consider weight bearing X-ray AP and lateral views with skyline only if patella involvement implicated.
  • US can be of value if confirmation of patella tendinopathy is required.
  • MRI rarely adds to diagnosis only indicated as second line investigation.
Surgical Criteria

No referrals should be made to secondary care unless the following criteria are met:

  • Patient has intrusive pain where 6-12 months of comprehensive conservative management has failed despite patient demonstrating motivation and adherence to rehabilitation and advice.


  • There is continued diagnostic uncertainty following review by interface that requires further specialist input.


Note that surgical interventions for anterior knee pain are not routinely commissioned.


Surgery is rarely indicated for anterior knee pain as not generally helped by surgery but examples of interventions rarely used are:

  • Arthroscopic debridement - time to drive 1-2 weeks, time to recovery 3 months.
  • Arthroscopic lateral retinacular release of PFJ (OA pathway) - time to drive 4-6 weeks, time to recovery 6 months.