Knee
Knee Imaging Pathway
In the majority of causes of knee pain, clinical examination is as good as imaging for diagnosis and management planning.
Diagnose osteoarthritis clinically without investigations if a person:
• Is aged 55 years or over
• Activity-related joint pains
• Has either no morning joint-related stiffness or morning stiffness that lasts no longer than 30 minutes.
• Functional impairment such as difficulty walking, climbing stairs, dressing or driving.
Xray is the first line investigation for osteoarthritis and MRI is NOT indicated when it is identified on an X-ray
MRI has a role when the diagnosis is unclear, the knee is unstable or suspected meniscal injury and the level of disability or pain is such that surgery is being considered. A knee Xray should be available from within 6 months of MRI request.
MR imaging can give both false positive and false negative results, especially with meniscal injuries and incidental findings are common and increase with age. Therefore MRI in patients >60yrs is innappropriate.
Primary care imaging should not be obtained for persistently locked knee or other acute severe injury. Imaging the post operative knee should also be via secondary care only.
Ultrasound is NOT indicated unless suspected patella or quadriceps tendon pathology or pes anerinus
Subcategory and Description
Imaging Recommendation
Anterior Knee pain (patellofemoral syndrome
• Pain at anterior knee/patella, can be associated with patella crepitus, clicking and stiffness.
Pain on patella compression tests and patella mobility.
• Variable pain area and pain levels.
• Patellar dysfunctions common in younger adult patients and adolescents, patients with
hyperextension of the knees, and in jumping activities
• Pain often associated with squatting, kneeling, lunging, stairs, and prolonged sitting (flexion based activities). Less pain on walking on flat, more on downhill.
No imaging Indicated
Knee osteoarthtitis
•Common over 50 years.
• Joint pain: usually worse on weight-bearing activities: standing, walking, upstairs walking. May also present with: decreased joint mobility, joint swelling, crepitus, and visual morphological changes of the knee.
• Stiffness: Can present with early morning stiffness> 30 mins or after prolonged inactivity.
• Variable presentation and pain levels.
Standing X-ray
Meniscal Tear - acute
•History of trauma, twisting injury often in weight-bearing, often describe clicking/popping sensation.
• History of true locking, giving way, effusion and inability to weight bear fully. • Lack extension/ locked/can lack end range flexion
• Positive meniscal test: McMurry’s, Thessaly’s, Scoop.
• Sharp pain on medial/lateral joint line, palpation painful.
• Urgent referral: if true locking or instability and significant weight bearing problems
Standing X-ray and consider MRI if <55 years
Meniscal Tear - chronic/degenerative
•Common after 40 years: degenerative tear can develop from minor incident or gradual onset, usually no significant trauma
• Pain, swelling and stiffness often present, reduced range of movement and inability to weight bear fully
• Pain often at medial/lateral joint lines worse with internal/external rotation
• If true locking see acute meniscal trauma pathway
Standing X-ray to assess degree of OA
Most do not require MRI
Ligamentous Injury
• Age: 16-60 most common
• Mechanism of injury important factor: associated trauma: twisting with foot planted common, valgus/varus stress, contact sports, skiing.
• May report popping/snapping sensation at time of injury
• Rapid swelling/effusion and pain
• Inability to carry on with activity
• Feeling of instability/knee giving way: assess ACL/PCL: positive Lachmans/Anterior Drawer, LCL: posterior Sag/posterior drawer
• Acute knee injuries: consider immediate referral to orthopaedics if complete ligament tear is suspected
MRI knee
with Xray if bone injury also suspected or older patient >55
Bakers cyst
• Swelling at posterior aspect of the knee joint: can fluctuate
• Pain/tightness and lump felt at back of knee
• Most common associated with underlying OA of the knee
• Pain associated with end of range extension or flexion
• Bakers cysts can rupture causing pain, redness and swelling in the posterior calf
Standing X-ray to assess degree of OA
Does not require MRI
Primary care management
•Analgesic ladder/NSAIDS as appropriate
• Activity modification: alternative pain free exercise rather than complete rest
• Provide Anterior Knee pain information leaflet: Arthritis Research UK and
NHS choices website
• Supportive footwear: shoes with medial arch support if indicated/ update them if old.
• MSK service referral if on-going pain and dysfunction; failure to respond after attempting early management > 12 weeks
•Analgesic ladder/NSAIDS as appropriate
• Weight Management advice if appropriate BMI <35 reduces symptoms and surgical complication rates
• Management devices eg walking aids, insoles, foot supports.
• Advise to remain as active as possible and continue with normal daily activities.
• Do not inject the knee if referral for knee replacement is being considered
• Provide patient information leaflet: Arthritis Research UK and NHS choices website.
• MSK service referral if on-going pain and dysfunction; failure to respond after attempting early management > 12 weeks
• RICE, analgesic ladder and NSAIDS as appropriate
• Relative rest: 1-2 weeks, walking aids to offload knee.
• Provide patient information leaflet: Arthritis Research UK and NHS choices website
• Early referral to MSK if severe pain and dysfunction < 2 weeks
• RICE, analgesic ladder and NSAIDS as appropriate
• Relative rest: 1-2 weeks, walking aids to offload knee (single use, opposite side to injury).
• Provide patient information leaflet: Arthritis Research UK and NHS choices website
• MSK service referral if on-going pain and dysfunction; failure to respond after attempting early management > 6 weeks
•Stable ligament injuries or older patient: Analgesia and NSAIDS as appropriate
• Relative rest: 1-2 weeks, walking aids to offload knee.RICE
• Provide patient information leaflet: Arthritis Research UK and NHS choices website
• Early referral (< 2 weeks) to MSK if severe pain and dysfunction/inability to weightbear
• MSK service referral in on-going pain and dysfunction; failure to respond after attempting early management > 6 weeks
• Analgesic ladder/NSAIDS as appropriate
• RICE guidelines in acute cases
• Walking aids to offload knee
• Provide patient information leaflet: Arthritis Research UK and NHS choices website
• Do not refer for cyst aspiration