Limited effectiveness of sonography in revealing hip joint effusion: preliminary results in 21 adult patients with native and postoperative hips.

Objective: The object of this study was to determine the effectiveness of sonography in the detection of hip joint effusions in both native and postoperative adult hips using arthrocentesis as a gold standard.
Materials and Methods: Twenty-one consecutive patients with clinical suspicion of hip joint effusion were examined on sonography by one of five musculoskeletal radiologists with experience in musculoskeletal sonography. All 21 patients underwent diagnostic arthrocentesis (fluoroscopic in 16, sonographic in five) to confirm the presence or absence of joint effusion. A retrospective analysis of the sonograms was made to assess the size of the distention of the anterior joint recess (anteroposterior dimension) and the echogenicity (anechoic or other relative to muscle), and correlation was made to the presence or absence of joint effusion.
Results: Joint effusion was seen on diagnostic arthrocentesis in 10 (48%) of the 21 patients. Seven of the 21 patients had native hips and 14 had prior hip surgery. Retrospectively, no significant difference was found with regard to the size of the anterior recess distention (p = 0.34) or echogenicity (p = 0.2) when comparing the patients with and without joint effusion.
Conclusion: Anterior recess distention and echogenicity could not reliably be used as an indicator of adult hip joint effusion, either in native or postoperative hips. Diagnostic arthrocentesis was necessary to establish or exclude the presence of hip joint effusion.