Usefulness of high resolution US in the evaluation of effusion in osteoarthritic first carpometacarpal joint

Objective: The aim of this study is to provide a reproducible and quantitative sonographic method for evaluation of effusion in the first carpometacarpal joint in osteoarthritis. Methods: High resolution sonography of the carpometacarpal joint of the thumb was earned out in 20 normal joints and in 57 joints from patients with osteoarthritis. A 10 MHz transducer was used. Results: The articular cavity appeared as a hypoechoic triangular area. In normal joints the mean values obtained by measuring the distance between the apex and the base of the triangle was 2.89 mm (SD 0.22). In osteoarthritic joints it was significantly increased (p<0.001). The authors assert that the presence of effusion is very likely if the value is greater than or equal to 3.33 mm (mean+2 SD). Conclusions: Sonography provides useful. reproducible, and quantitative data for detection of effusion within the first carpometacarpal joint.