Clinical assessment of effusion in knee osteoarthritis-A systematic review

Objective: The aim of this systematic review was to determine the validity and inter- and intra-observer reliability of the assessment of knee joint effusion in osteoarthritis (OA) of the knee.

Methods: MEDLINE, Web of Knowledge, CINAHL, EMBASE, and AMED were searched from their inception to February 2015. Articles were included according to a priori defined criteria: samples containing participants with knee OA; prospective evaluation of clinical tests and assessments of knee effusion that included reliability, sensitivity, and specificity of these tests.

Results: A total of 10 publications were reviewed. Eight of these considered reliability and four on validity of clinical assessments against ultrasound effusion. It was not possible to undertake a meta-analysis of reliability or validity because of differences in study designs and the clinical tests. Intra-observer kappa agreement for visible swelling ranged from 0.37 (suprapatellar) to 1.0 (prepatellar); for bulge sign 0.47 and balloon sign 0.37. Inter-observer kappa agreement for visible swelling ranged from -0.02 (prepatellar) to 0.65 (infrapatellar), the balloon sign -0.11 to 0.82, patellar tap -0.02 to 0.75 and bulge sign kappa -0.04 to 0.14 or reliability coefficient 0.97. Reliability and diagnostic accuracy tended to be better in experienced observers. Very few data looked at performance of individual clinical tests with sensitivity ranging 18.2-85.7% and specificity 35.3-93.3%, both higher with larger effusions.

Conclusion: The majority of unstandardized clinical tests to assess joint effusion in knee OA had relatively low intra- and inter-observer reliability. There is some evidence experience improved reliability and diagnostic accuracy of tests. Currently there is insufficient evidence to recommend any particular test in clinical practice.