[Radiological opacities after intra-articular injection of osmic acid. Relationship with the injection site (author's transl)].

Abnormal radiological opacities are sometimes observed after intra-articular injection of osmic acid. These opacities are radio-opaque because osmium is a heavy metal (atomic number = 76). They are usually found near the suprapatellar pouch which is the usual injection site. A parasynovial injection (or back flow from the joint cavity) of some of the osmic solution, followed by concentration and fixation of the osmic deposits at this level, seems to be the cause of these radiological opacities. This could be the reason for the poor clinical results encountered in some cases of osmic acid therapy followed by such deposits.