Concept of radiosynovectomy a novel approach in the treatment of joint disorders

Joint disorders are relatively common in any society. A large percentage of the population in all age groups suffer from a variety of joint disorders, some of which are of chronic nature. It is a long suffering from pain, deformity and disability. One of the most common causes is rheumatoid arthritis. Conventional long-term treatment with various combinations of drugs can bring relief in many cases. But many joints need additional local therapy. Mostly corticosteroids are injected into the joint to suppress the inflammatory process localized in the synovia. In some cases, surgery is also performed.

Radiosynovectomy (also known as Radiosynoviorthesis) is a novel method of treatment for such joint disorders. After careful evaluation and diagnosis, a small amount of radioisotope is injected into the joint in the same manner as cortisone is installed. These radioisotopes emit beta rays which penetrate only from fraction of a millimeter to a few millimeters and destroy the inflammatory tissue and thus reduce swelling and pain. In many cases, if applied in relatively early stage, complete restoration of the joint is possible.

Although rheumatoid arthritis is the main indication for radiosynovectomy, many joints having activated arthrosis in which inflammation of the synovia plays a role, can also be treated successfully. With the application of a radiation dose of 7000 to 10,000 rem to the synovia, the proliferative tissue is destroyed, secretion of fluid and accumulation of inflammation causing cellular compounds of the blood stops and finally the joint surfaces get fibrosed. This provides long term relief and often total normalization of the joint.

Different types of radioisotopes are used for different joints. Small finger joints require radioisotopes like Erbium-169 which emits beta rays of very low energy capable of penetrating 0.3 to 1 mm. of tissue. Middle sized joints like elbow, wrist and shoulder require radioisotopes like Rhenium-186 which emits beta rays with tissue penetration of 1.2 to 3.7 mm. Large joints like knee joint need Yttrium-90 which gives rays having a tissue penetration of 3.6 to 11 mm. The radioisotopes are injected in colloidal form so that they remain in the synovium of the joint and not transported by lymphatic vessels or blood to any part of the body. There is no risk of radiation to any other organ of the body or to the environment. So the procedure can be performed on ambulatory patients.

With the availability of Holmium (Ho-166) in colloidal form and expected P-32 colloids from BRIT, this modality of treatment is poised to be economical and hence become popular in India.