[Extraosseous accumulation of 99mTc-HMDP in knees with synovial effusion]

In the presence of extraosseous activity seen in the late phase of the bone scintigraphy (BS) localized in the distal femur of patients prior to radiation synovectomy, we decided to review the frequency of this finding in 20 patients (24 joints) and its relationship with scintigraphic and clinical parameters. Mild soft tissue accumulation was seen in the late phase of the BS in 14 out of 24 joints, without association between this finding and knee uptake in vascular blood pool and late phases of the BS. However, a significant association with synovial effusion was found, and patients with higher degree of effusion presented extraosseous activity more frequently. In conclusion, we think that soft tissue accumulation in the late phase of the BS is a sign of synovial effusion.