BAKERS CYST IN RHEUMATOID-ARTHRITIS - AN ULTRASONOGRAPHIC STUDY WITH A HIGH-RESOLUTION TECHNIQUE

Objective. To determine the prevalence of popliteal cyst (Baker's cyst ) in rheumatoid arthritis (RAJ, through the use of a very sensitive an d non-invasive method high resolution ultrasonography. The present is the first such report in the literature. Methods. Ninety-nine unselect ed consecutive patients with RA, after undergoing routine clinical and laboratory evaluation had knee radiographs and ultrasound examination s of both knees, the popliteal fossae and calves, using an Ultramark 9 ATL apparatus with a 3 MHZ curved array and 10 MHz linear array heads and color doppler ability. Results. A Baker's cyst was detected in 47 patients (47.5%) and in a total of 67 out of the 198 knees (33.8%). Fo ur of the 67 cysts were ruptured. Only 29 of the 67 cysts (43.3%) had been diagnosed clinically. A statistically significant correlation was found between the presence of a Baker's cyst and clinical and radiolo gic involvement of the knee by rheumatoid arthritis (p < 0.025, and p < 0.05 respectively). There was a highly significant correlation betwe en the presence of a cyst and ultrasonographically demonstrated joint effusion (p < 0.001). Conclusion. Baker's cyst is very common in RA bu t it may escape clinical detection. High resolution ultrasound scannin g of the area is a simple, highly sensitive and non-invasive technique able to overcome this problem. Therefore, it should be more widely em ployed by clinicians in the diagnosis of popliteal cysts, which may so metimes be accompanied by significant morbidity.