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Knee Pain

Checked: 12-03-2024 by Rob Adams Next Review: 12-03-2026

Overview

Abnormalities found on scans in asymptomatic people

(Copyright: Lee Higginbotham)

Knee pain is very common, and most often represents a benign mechanical problem. Over the age of 45/50 there is commonly a degree of osteoarthritic changes, and it often presents a grumbling course with periodic exacerbations and remissions. Most can be managed in primary care.

Imaging is not always helpful as it is common to find ‘abnormalities’ on x-ray, ultrasound and MRI scans in the asymptomatic population. It should only be considered in the presence of red flags, or if it is likely to change management.

Recommendations from recent audit of MRI knee requests, for patients over 50 years old, at UHBW (May 2023) - see full poster in Resources section below

Clinically diagnose OA without imaging when appropriate (as per NG 226)
XR is needed before MRI (unless specific reason)
Acute injuries : ED or acute knee clinic/ fracture clinic (does not need imaging to refer).
Requests sent without clear indication or prior XR are likely to be returned until XR performed.

Here is a link to the excellent CKS guidelines: https://cks.nice.org.uk/topics/knee-pain-assessment/

Remember hip problems may present as knee pain, and also consider spinal referred pain.

Consider the patients age to help guide diagnosis eg. osteoarthritis is the most common cause of knee pain in over 50’s.

For further information and more detailed clinical examination consider using: https://www.physio-pedia.com/Knee_Examination

Who to refer

Please see:

GP Knee Referral Flow Chart. - this gives advice on appropriate management and or referral for knee pain. The flow chart will guide you to which service is most applicable for different patient scenarios.

Consider referral in the following circumstances:

Persistent pain

Most GPs will be able to use their FCP (First contact Practitioner) for further evaluation and advice about appropriate imaging if required.

Pain that is persistent and not responding to conservative measures may need onward referral to MSK/ physio services as below:

MSK Physio services -this page includes referral criteria.

For advice on appropriate imaging for persistent knee pain please see Imaging section below.

Trauma

If there has been significant trauma consider using the Ottawa Knee rules to help guide need for imaging and/or referral to ED/ Urgent Treatment Centre.

Knee pain may also come on after an acute event during activity (eg dancing, tennis or just walking with an awkward stumble). The patient may feel a sudden pop and pain. Some patients may also experience acute locking (an inability to straighten the knee fully) as an acute event. This is often intermittent and usually after trauma.

If concerned about possible acute, traumatic damage to cartilage/ligament or meniscal injury that may require surgery, consider referral to the Acute Knee Clinic. Referral criteria can be found in the link below:

Acute knee clinic page

Please note this clinic is usually not appropriate for older patients or those with previous history of grumbling knee pain as they are more likely to have had an acute flair of degenerate changes.

Degenerative Meniscal Tears

Many pateints with degenerative meniscal tears have no event that the patient can remember. Instead they notice a slow onset of pain with activities such as squatting, twisting and after activity (eg. gardening, cleaning) then pain and swelling the next day.

As per BASK (British Association for surgery of the knee) guidelines (2), in patients with <3 months symptoms from a degenerative, meniscal tear they should be offered optimal non-operative treatment (eg physio, exercise therapy etc) and re-assessed. If symptoms persist >3 months then non-urgent arthroscopic surgery may be considered (refer via Musculoskeletal Interface (MSKI) Service )

Atraumatic acute swollen/red knee:

If infection/septic arthritis is suspected, refer to A+E (call orthopaedic on-call first). Please note that in a new presentation of an acute mono-arthritis it can often be difficult to determine if there is underlying infection or inflammation. If there are concerns about infection this needs to be ruled out first.

Multiple Joint Involvement

If there is multiple joint pathology and a systemic arthritis is suspected, consider referral to rheumatology via the EIA (Early Inflammatory Arthritis) pathway. (if criteria are met).

Red Flags

Red flags should be considered for:

Infection (septic arthritis or osteomyelitis).
Tumours (bone tumour, soft-tissue sarcoma, metastases, haematological cancer, or neuroblastoma).
Inflammatory polyarthritis
Insufficiency fracture
Locked knee
Inability to weight bear

Before referral

Immediate Management

If there are no red flags or indication for referral to ED then initial management should include patient led conservative intervention such as:

OTC pain medication (NSAIDs preferable if patients can tolerate).
Rest from painful activities.

Exercise

Exercise can be helpful in managing knee pain folllowing injury and also can be particularly useful in OA. See links below:

Weight Loss

Weight can have a significant impact keen pain and weight loss should be advised if this is a contributing factor.

Pain Management

Pain management courses such as Escape Pain can be a useful exercise programme for knee and hip OA.

Injection

Injecction of steroid and local anaesthetic can sometimes be useful in the primary care management of atraumatic knee pain. Steroid is useful for the management of recurrent effusions associated with knee pain, particularly when there is tricompartmental change and the surgical treatment is total knee replacement. However there are concerns regarding the widespread use of steroid injection on a number of accounts:

If there is a repairable lesion such as a meniscal root tear then use of a steroid injection will delay potential curative surgery.
There is concern over local anaesthetic toxicity intra-articular. Further information on knee injections can be found below. Clinicans should only undertake injections if appropriately trained and confident in injection techniques. Alternatively refer to the MSK team for consideration of an injection.

http://www.sirona-cic.org.uk/advice-information/leaflet-library/musculoskeletal-msk-services/leaflet-corticosteroid-injections/

https://www.nhs.uk/conditions/steroid-injections/

Imaging

If the patient has signs of OA (over 50, gradual onset, non-specific knee pain) MRI is not indicated. Use XR if suspicious of OA and one has not been done recently.

Degenerate meniscal tears are common findings in over 50’s and are often associated with early degenerative changes. These are rarely managed operatively – there are two exceptions at present:

the acute meniscal root tear with a well preserved knee joint
the degenerate meniscal tear with a target lesion caught under the meniscus or in the medial gutter.

As such MRI does not change management and is therefore not indicated in primary care, but if the symptoms are of a normal knee and then a sudden onset of pain, usually with a ‘pop’ sensation during increased activity (eg dancing/sport) consider referral to the acute knee clinic (if criteria are met). If the symptoms are slower onset but not settling then referral to the MSK interface service for consideration of MRI to delineate a meniscal tear with a target lesion is appropriate.

Ultrasound in rarely useful in the early management of knee pain. Please see referral flow chart.

If trauma at onset and suspicious of acute internal derangement consider MRI to assess ligament integrity. Alternatively, consider referral to the acute knee clinic.

Most GPs will be able to use their FCP (First contact Practitioner) or MSK team for further evaluation and appropriate imaging if required. Those GPs who have had further training and are particularly confident in MSK, may wish to order MRI scans direct, but would need to be asking a specific question which might change management, otherwise they may find radiology reject their request.

Resources

The following links may be useful for managing knee pain in primary care;

References

(1) UHBW Audit: Do MRI knee requests from primary care, in patients over 50, meet local guidelines? (May 2023)

(2) Meniscal surgery guidlines - Professional (baskonline.com)

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