Diagnostic Value of History Taking and Physical Examination to Assess Effusion of the Knee in Traumatic Knee Patients in General Practice

Kastelein M, Luijsterburg PA, Wagemakers HP, Bansraj SC, Berger MY, Koes BW, Bierma-Zeinstra SM. Diagnostic value of history taking and physical examination to assess effusion of the knee in traumatic knee patients in general practice.ObjectiveTo assess the diagnostic value of history taking and physical examination for knee joint effusion in patients with a knee injury who consult their general practitioner (GP). In addition, to determine the association between effusion seen on magnetic resonance imaging (MRI) and internal derangement of the knee.DesignProspective, observational cohort study.SettingPrimary care.ParticipantsPatients (N=134) aged 18 to 65 years with a traumatic knee injury who consulted their GP.InterventionsNot applicable.Main Outcome MeasuresPatients filled out a questionnaire, underwent a standardized physical examination and underwent an MRI scan to assess the presence of effusion. Multivariate logistic regression analysis was used to determine the diagnostic value of history taking and physical examination (P<0.10) as assessed by sensitivity, specificity, predictive values, and likelihood ratios. The relationship between effusion and internal derangement of the knee was assessed with a chi-square test.ResultsOf the 134 participating patients, 42 had knee joint effusion seen on MRI. Multivariate analysis showed an association with knee joint effusion for the symptom “self-noticed swelling” (history taking) and for the “ballottement test” (physical examination). The likelihood ratio positive (LR+) was 1.5 for self-noticed swelling and 1.6 for the ballottement test. These 2 combined improved the diagnostic value to an LR+ of 3.6. Effusion showed a positive association with internal derangement of the knee (chi-square 9.5); 31 of the 42 patients with knee joint effusion had internal derangement of the knee.ConclusionsIn patients with traumatic knee injury, knee joint effusion is frequently seen on MRI. The combination of self-noticed swelling and the ballottement test was of diagnostic value. Knee joint effusion was associated with internal derangement of the knee.