How to assess knee joint effusion in knee osteoarthritis

Knee joint effusion is a common symptom in individuals with knee OA. Studies revealed the evidence of knee effusion in nine out of ten people with knee OA, with 55% having a moderate to large effusion. Thus, the assessment of knee effusion is a crucial part of the physical examination in these patients. Although, a broad range of clinical tests for knee effusion exists, the knowledge of the reliability and validity of these tests is lacking. 

Knee joint effusion is a common symptom in individuals with knee OA and is evident in nine out of ten people. Thus, the assessment of knee effusion is a crucial part of the physical examination in these patients. 

This systematic review analysed a total of 10 studies and investigated the reliability and validity of clinical assessments against ultrasound effusion. Eight articles focused on the reliability and four articles focused on the validity of clinical assessments. The tests which were investigated were: visual inspection, the bulge sign/ sweep test, patellar tap/ballottement, balloon sign, combination tests. 

The range of reliability in the clinical assessment was overall poor to moderate. Studies which compared the effusion assessments to US showed a great variation in sensitivity and specificity. However, based on the current evidence no individual test can be favored over another. The only evidence which could be detected was that clinical experience impacted on the reliability. Furthermore, in comparison to individual testings the combination of tests for effusion appears to improve sensitivity. 

> From: Maricar et al., Semin Arthritis Rheum (2015) (Epub ahead of print). All rights reserved to The Author(s). Click here for the Pubmed summary.