Direct assessment of synovial blood flow and its relation to induced hydrostatic pressure changes.

A method for measuring synovial blood flow changes using the laser Doppler technique is described. Mean blood flow and mean pulse amplitude decreased by 50-70% in relation to the reference level when the intra-articular hydrostatic pressure in effusive knee joints of patients with rheumatoid arthritis was increased. As an increase of intra-articular pressure of as little as 20 mmHg decreased synovial blood flow significantly it is suggested that hypoxia may occur in vivo during joint use in the presence of an effusion. This may be of aetiopathogenetic importance for tissue destruction and the persistence of chronic synovitis.