The knee is susceptible to trauma and is often the site of systemic disease. A thorough knee assessment is essential in determining the cause and, therefore, appropriate management. See also separate article Knee Assessment.
See also article on Sports Injuries.
- Ligament injury (see also separate article Knee Ligament Injuries).
- Fractures and dislocations: see also separate articles Knee Fractures and Dislocations, Femoral Fractures and Tibial and Fibular Fractures (including Horse Rider's Knee).
- Meniscus injury (see also separate article Knee Cartilage Injuries).
- Add notes to any clinical page and create a reflective diary
- Automatically track and log every page you have viewed
- Print and export a summary to use in your appraisal
- Reactive arthritis (Reiter's syndrome).
- Juvenile chronic arthritis.
- Rheumatoid arthritis.
- Pseudogout (calcium pyrophosphate deposition disease).
- Osteoarthritis and overuse syndrome.
- Sudden onset (within four hours of trauma) of pain and swelling - suggests a traumatic haemarthrosis, and damage within the joint, requiring referral. Traumatic haemarthrosis is increasingly seen in patients on warfarin. Haemarthrosis may also be associated with clotting disorders, eg haemophilia.
- Findings suggesting a fracture include:
- Mechanism of injury involving a high-velocity collision.
- An audible/palpable 'pop' at the time of injury.
- Age greater than 55 years.
- Inability to bear weight immediately after the injury.
- Anterior cruciate ligament (ACL) injuries usually occur after noncontact deceleration. There may be hyperextension, often accompanied by a 'pop'. They are unable to continue sport participation, and there is associated knee instability.
- The posterior cruciate ligament (PCL) is injured far less often than the ACL. The usual mechanism of injury is a blow to the anterior proximal tibia with the knee flexed, eg tripping over a hurdle.
- More gradual accumulation of fluid might suggest an effusion secondary to traumatic synovitis (eg cartilage injury), or to an exacerbation of osteoarthritis.
- Sudden onset of pain without trauma - acute gout typically starts with a sudden onset of pain.
- Less dramatic onset might imply pseudogout, an exacerbation of osteoarthritis, reactive arthritis or septic arthritis.
The pain of most of these conditions is severe.
- Septic arthritis: systemic symptoms are likely, although they are not always present. Risk factors include:
- Intravenous drug use.
- Lack of traumatic injury.
- Recent sexual encounter.
- History of abnormal joint.
- Reactive arthritis: systemic symptoms, especially a low-grade fever, conjunctivitis and urethritis. There may be a history of recent diarrhoeal illness or symptoms or risk of sexually transmitted disease.
- Connective tissue disease: other joints and systems affected, eg iritis, rashes, proteinuria.
- Medications: diuretics and aspirin may provoke attacks of gout.
- Tumour is suggested by a history of night pain, fevers, night sweats and unintentional weight loss.
Careful examination of the knee, to identify the structure causing the swelling.
- Effusion: a large effusion will be obvious. Smaller effusions may be missed but synovial fluid can often be 'milked' from one patellar groove to the other.
- Thickened synovium is non-fluctuant.
- Osteophytes may be palpable.
- Crepitus may be apparent on moving the joint.
- There may be limitation of movement or locking of the joint.
- ESR, CRP: may be useful in excluding inflammatory joint disease or septic arthritis.
- X-ray: AP and lateral views. Criteria for X-ray include the inability to bear weight, presence of effusion and ecchymosis.
- FBC and differential: chronic inflammation may cause anaemia.
- Renal function: can be impaired in gout.
- Uric acid: may be raised in gout; however, a normal uric acid finding does not exclude gout.
- Joint aspiration: for diagnosis of septic arthritis, or diagnosis of crystal arthropathy or for comfort.
- MRI scan: a useful tool for evaluating meniscal and ligamentous knee injuries but it is unable to identify articular cartilage lesions clearly. The Direct Access Magnetic resonance imaging: Assessment for Suspect Knees (DAMASK) trial looked at the use of direct access MRI and reported that, whilst it increased GPs' confidence in the management of knee problems, it did not reduce the rate of referral to orthopaedic services. A further study using patient questionnaires found that GP access resulted in a small but significant increase in patients' knee-related quality of life but not in functional improvement.
The management will depend on:
- The nature of the cause of the swelling.
- The degree of swelling.
- The medical history and social circumstances of the patient.
Referral is indicated if there is any doubt as to the underlying cause. Admit immediately if septic arthritis is suspected or after significant trauma.
Further reading & references
- Knee Joint - Anatomy & Function; Knee Joint - Anatomy & Function, arthroscopy.com
- Landewe RB, Gunther KP, Lukas C, et al; EULAR/EFORT recommendations for the diagnosis and initial management of patients Ann Rheum Dis. 2010 Jan;69(1):12-9. Epub .
- Johnson MW; Acute Knee Effusions: A Systematic Approach to Diagnosis. American Family Physician, April 2000.
- Jackson JL, O'Malley PG, Kroenke K; Jackson JL, O'Malley PG, Kroenke K; Evaluation of acute knee pain in primary care. Ann Intern Med. 2003 Oct 7;139(7):575-88.
- Examination of the knee, Wheeless' Textbook of Orthopaedics
- Vaz CE, Camargo OP, Santana PJ, et al; Accuracy of magnetic resonance in identifying traumatic intraarticular knee lesions. Clinics. 2005 Dec;60(6):445-50. Epub 2005 Dec 12.
- Brealey SD; Influence of magnetic resonance of the knee on GPs' decisions: a randomised trial. Br J Gen Pract. 2007 Aug;57(541):622-9.
- No authors listed; Effectiveness of GP access to magnetic resonance imaging of the knee: a Br J Gen Pract. 2008 Nov;58(556):e1-8; discussion 774.
- Weston V, Coakley G; The British Society for Rheumatology (BSR) Standards, Guidelines and Audit Working Group; British Society for Antimicrobial Chemotherapy; British Orthopaedic Association; Royal College of General Practitioners; British Health Professionals in Rheumatology. Guideline for the management of the hot swollen joint in adults with a particular focus on septic arthritis. J Antimicrob Chemother. 2006 Sep;58(3):492-3. Epub 2006 Jul 19.
|Original Author: Dr Hayley Willacy||Current Version: Dr Colin Tidy||Peer Reviewer: Prof Cathy Jackson|
|Last Checked: 19/04/2012||Document ID: 2363 Version: 27||© EMIS|
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.