Pre-existing conditions or conditions 
suggestive of osteoarthriti

+ Osteoarthritis or chondal lesions shown
 in the past x- rays, MRI or knee
arthroscopy (+)
+ HX of knee fracture and/or surgery
+ Obese patient > 40 years old 
+ Non-obese patient > 50 years

Non-urgent conditions

+ Pain <6 weeks
+ Patient < 50 years old
+ Multiple joint involvement
+ Bilateral symptoms
+ Knee "giving way"
+ Non-traumatic synovitis

Acute conditions

+ Recent sprain
+ Locked knee
+ Stopped walking
+ Great pain
+ Unstable ligament
+ Knee pain in a child Pain/swelling 
    > 6 weeksBaker’s cyst 

At-risk condition

+ Suspected fracture
+ History of cancer
+ B symptom
+ Suspected metastases
+ Severe knee trauma
+ Post-traumatic knee swelling
Conservative treatment
(6 weeks)

+ Walking aid
+ Weight loss
+ Rest
+ Analgesics
If 6-week
treatment failed
+ X-ray of knee AP lying and lateral view 
+ SS view- patella 30°
+ If associated inguinal pain,
x-ray of pelvis AP and hip
Crutches and ...
Pain in
"give away"
knee pain
Extensor device problem
Refer to 
If failed
Care by family physician (Option)
Negative (-)
Positive (+)
( +/- )
+ Locked knee with signs of osteoarthritis
+ Moderate/severe Gonarthrosis
+ Fracture
+ Suspicious bone lesion
+ Abnormal patella position
+ Ligament injury
+ Locked knee without osteoarthritis
+ If soft tissue tumour palpable
+ If fever and/or shivering
+ If cellulitis
+ Painfull weight bearing
+ Patella Osteoarthritis
+ Normal knee
+ Mild osteoarthritis
Crutches and ...
+ Emergency physician
+ Laboratory
+ Orthopedist on call
Refer to 
+ Monoarticular synovitis
+ Monoarticular synovitis
+ Joint space pain (internal or external) with or without swelling > 6 weeks
IA Injection:

+ viscosupplementation
Blood tests
Refer to 
 + Mild Osteoarthritis
+ Standing x-ray No osteoarthritis
Joint space narrowing
Knee Pain Algorithm
Refer to

1) Most cases of knee pain in patients over 50 years of age or in younger obese patients are related to degenerative changes rather than meniscus tears. In short, knee pain in patients under 50 years of age is most often due to meniscus tears that are surgical, while in patients over 50 years of age, meniscus tears are non-surgical if with osteoarthritis and narrowing of joint space present.

2) Asymptomatic meniscus tears requiring no treatment are common in patients over 50 years of age. It is the same with osteoarthritis. Many degenerative meniscus tears are asymptomatic. Mostly symptomatic meniscus tears in patients whose knee are non-osteoarthritic or have adequate cartilage height on standing AP views give good surgical response.

3) With x-rays or a knee arthroscopy already showing degenerative changes, there is no use for MRI, as it will show more advanced degenerative knee changes than the x-rays.

4) If a Baker’s cyst is present, x-rays are taken; if osteoarthritis is present, there is rarely indication for an ultrasound. If osteoarthritis is absent, the ultrasound may be useful.

5) For knee sprain, rule out knee fracture and osteoarthritis. If x-rays are negative, you can initiate RICE treatment for six weeks. An MRI scan may be indicated only if the clinical profile shows no improvement after six weeks.

6) After taking the standard x-rays, do not wait for more advanced imaging results if a neoplastic or infectious disorder is suspected. Order the laboratory tests required and quickly contact the specialist on call to discuss the case.

7) A knee giving way is often due to pathology of the knee extensor mechanism. A locked knee is often due to an intra-articular problem. Knee stiffness is not an actual locked knee and it may be related to either an intra-articular or extra-articular problem.

8) In patients with a BMI > 35, consider weight loss, a dietetic consultation or a group weight reduction program (whether or not x-rays are normal).

9) In frontline care, always start by ruling out knee osteoarthritis. If the examination is normal, an MRI scan may be requested to diagnose a meniscus tear if symptoms have been persistent for over six weeks. With knee osteoarthritis, do not try to diagnose a meniscus tear, as this lesion will be ignored in the treatment plan. From an orthopaedic perspective, the treatment of osteoarthritis and mechanical signs prevails, regardless of the result of the MRI scan about the meniscus.

10) For mono-articular knee swelling in patients over 50 years of age or younger obese patients with an ineffective NSAID treatment, consider an intra-articular corticosteroid or viscosupplement injection. In younger patients, if there is pain in the internal or external compartment of the knee, especially with a positive McMurray test, a meniscus tear should be suspected.

11) With significant degenerative changes on the standing x-ray of knee with loss of joint height, very often there are associated meniscus tears that should not be investigated, as it does not affect the clinical decision, which consists in solely taking care of the osteoarthritis treatment.

12) If x-rays show moderate to severe degenerative changes, continue the conservative treatment or refer the patient to orthopaedics. An MRI is certainly not necessary or indicated to obtain an orthopaedic consultation.

13) In the emergency room, with a knee injury due to a sprain or contusion, the need for a knee x-ray based on the Ottawa Knee Injury criteria is very sensitive to diagnose a fracture. With difficulty bearing weight and a normal x-ray, apply the RICE principle, crutches, no weight bearing, and orthopaedic follow-up in the outpatient clinic between five to ten days. This is more cost-effective and there is no emergency to perform a CT or MRI scans to identify a small non-displaced fracture of the knee, an ACL tear and/or a meniscus tear.

14) An intra-articular corticosteroid injection for swelling may provide relief of varying duration. The effectiveness of a viscosupplement injection is much debated. It should be avoided if bone or knee joint deformity is severe.

15) An MRI scan should not compensate for an unclear interview and physical examination. If in doubt, it is much more economical to refer the patient to orthopaedics or physiatry than ordering an MRI scan.

16) Even if the incidence of osteoarthritis is very low in patients (< 50 years), it is not suggested to request a knee MRI scan with no x-rays taken beforehand. Always rule out bone or articulation problems before investigating soft tissues. The incidence of knee osteoarthritis is low in young non-obese patients presenting post-traumatic internal knee pain with symptoms that have been persistent for over three months. A meniscus tear can then be suspected.

17) Surgical treatment options are knee arthroscopy, proximal tibia osteotomy, and knee arthroplasty.

18) Request an inflammatory profile in case of persistent pluriarticular swelling and refer the patient to rheumatology, if necessary.

19) Mild to moderate knee osteoarthritis cases that require an MRI scan are clinical refinement that falls within the competence of the orthopaedist

20) If x-rays are normal or if there are very mild degenerative changes on standing AP views with preservation of the cartilaginous space or femoro-tibial height, an MRI scan or orthopedic assessment may be considered if significant mechanical symptoms have been present for three months.

21) Indications for knee MRI are:
22) Indications for MRI scan of knee for cases seen in the emergency room: