Scintigraphic findings in the rheumatoid knee joint

An increased uptake of 99m-technetium methylenediphosphonate was found in 42 knees of 24 patients afflicted with rheumatoid arthritis. All the 23 knees which were painful and the 21 knees which had synovitis showed an increased concentration of isotope. Articular space narrowing was observed in 26 joints, all but one of which were subjected to increased isotopic accumulation and synovitis. The degree of radiologic cartilage destruction correlated significantly with the isotopic uptake. In the early stages of rheumatoid arthritis, the isotopic uptake was found to be heterogeneous within the joint in one half of the cases. In the later stages, with a narrowed articular space and valgus angulation, the isotope was concentrated to the lateral side of the joint, while joints with varus angulation had a more symmetric distribution. The degree and distribution of uptake seemed to be governed by several factors, among others, inflammatory activity and mechanical load.