The value of colour Doppler sonography of the knee joint: a useful tool to discriminate inflammatory from non-inflammatory disease?

OBJECTIVE

To determine the diagnostic value of colour Doppler ultrasound (CDUS) in patients with inflammatory arthritis (IA) vs non-inflammatory disease (e.g. OA) of the knee joint.

METHODS

Standardized CDUS examinations were performed in 111 knee joints of 106 patients (70 women and 36 men) presenting with severe OA (n = 72) or confirmed IA (n = 39) of one or both knee joints to determine the degree of synovial inflammation in a semiquantitative fashion. To definitely distinguish inflammatory from non-inflammatory disease, SF was obtained from every patient within 24 h after sonography and analysed SFs containing ≤1000 white blood cells (WBC)/µl were considered non-inflammatory, whereas ≥5000 WBC/µl were classified as inflammatory.

RESULTS

The CDUS sum score of OA patients was determined to be 3.3 (range 0-8). In contrast, IA patients exhibited significantly elevated synovitis score of 5.3 (range 3-9) (P < 0.001). However, high synovial CDUS activity could be observed in OA patients sporadically. Therefore, there is no definitive CDUS threshold that clearly separates OA from IA patients.

CONCLUSION

CDUS is a valuable instrument to assist clinicians in distinguishing OA from IA of the knee joint, but nevertheless should always be interpreted within the clinical context.