Two European medical societies have collaborated on the first treatment guidelines for acute knee swelling that incorporate both rheumatology and orthopedic surgery perspectives.
The European League Against Rheumatism (EULAR) and the European Federation of National Associations of Orthopedics and Traumatology (EFORT) based their 10-point guideline on an extensive literature search, Dr. Robert B.M. Landewe wrote in the Annals of the Rheumatic Diseases (doi:10.1136/ard.2008.104406).
Where data were insufficient, the joint panel relied on expert consensus, said Dr. Landewe of Maastricht (the Netherlands) University Medical Center. Both international societies will start to implement the recommendations by using them as a template for discussions with the stakeholders of the target population [including primary care providers].”
The joint task force comprised 11 rheumatologists and 12 orthopedic surgeons, who met twice under the leadership of a clinical epidemiologist and a research fellow. The treatment guidelines were aimed at both acute and recent-onset (within the past 4–6 weeks) knee swelling, which, the experts reasoned, would encompass both trauma- and disease-related pathology.
The literature search yielded 48 articles upon which the panel based its 10 recommendations.
1. A clinical examination is necessary to confirm acute knee swelling.
Acute knee swelling is a common problem, occurring in up to 54% of the population, the panel noted. However, many self-referred cases do not show an increase in the volume of the knee.
2. Timely referral is necessary when the examination yields a suspicion of septic arthritis, trauma, tumor, or inflammatory arthritis.
Suspected septic arthritis should be considered an emergency that requires an immediate expert examination. Patients with suspected trauma should also be seen immediately. Suspected bone tumors require a semiacute referral of within 1 week to an orthopedic surgeon with a speciality in bone tumors. Patients with possible inflammatory arthritis should be seen by a rheumatologist within 6 weeks.
3. A complete medical history is also an important diagnostic tool.
A careful, thorough history should be taken, noting medical comorbidities, medication, malignancy, hemorrhage, and the speed of pain onset. Fever is also an important clue to the possible nature of knee swelling.
4. The physical exam should focus on the affected knee but include the unaffected knee as well as an assessment of other joints.
Joint assessment should include the localization and characteristics of the swelling, the presence of any effusion, joint stability, pain, skin temperature, and appearance. A general physical exam is valuable only if the joint pathology may be part of a systemic illness.
5. Lab tests are advisable in patients with nontraumatic knee swelling.
These may include white blood cell count and acute phase reactants to help exclude septic arthritis. A baseline C-reactive protein level may be useful in patients with suspected inflammatory arthritis. For suspected gout, serum uric acid measurements are indicated.
6. Patients with suspected septic, crystal, or inflammatory arthritis should undergo joint fluid aspiration.
Joint fluid should be examined for leukocytes, crystals, and bacteria. In cases of trauma-related effusion, the panel was split on the usefulness of hemarthros aspiration. “Evacuation … was considered only helpful in cases with major effusion and no acutely scheduled surgical intervention.” The panel agreed that aspiration is contraindicated in cases of suspected tumor, because of the possibility of seeding malignant cells.
7. A plain x-ray in two planes is enough to identify trauma or erosive changes, cartilage calcification, or cartilage thinning. An ultrasound may be helpful in detecting joint effusion and synovial hypertrophy.
Most studies indicate that ultrasound performs just as well, and that MRI could lead to an overestimation of pathology.
8. Diagnostic arthroscopy is indicated only in exceptional cases.
The data do not support the routine use of this procedure in patients with acute knee swelling, unless there is high suspicion of an intra-articular infection, such as by Mycobacterium tuberculosis or yeasts. “In light of the invasiveness of the procedure and the risk of complications, the expert committee felt unanimously that arthroscopy for diagnostic purposes solely cannot be justified and should therefore be abandoned.”
9. Specific therapies can't begin until an appropriate diagnosis is made.
But because making a firm diagnosis may take some time, general measures can be employed to relieve pain and other symptoms.
10. Noninterventionist therapies, like cold packs, splints, and simple analgesics or nonsteroidal anti-inflammatory drugs, can be used to ease symptoms.
A plan radiograph is enough to identify trauma or erosive changes, cartilage calcification or thinning. ©American College of Rheumatology Clinical Slide Collection, 1972–2004