Leakage of radioactive particle systems from a synovial joint studied with a gamma camera. Its application to radiation synovectomy.

UNLABELLED: We have determined rates of leakage of radioactivity from a rabbit synovial pouch in vivo for a number of particle systems of varying sizes and differing resistance to degradation. The estimates were made using a gamma scintillation camera and without killing the test animals. The lowest leakage at twenty-four hours was seen with inert carbonized microspheres and the highest rates were seen with surface-labeled particles of biodegradable denatured human serum albumin and with erythrocytes. The carbonized microspheres had no adverse long-term effects on the health of the animals' articular cartilage. CLINICAL RELEVANCE: Results obtained with inert particles indicate that reducing the biodegradability of the particle or increasing its diameter, or both, reduces radioactivity losses from the knee joint. Large (twenty-five-micrometer-diameter) microspheres of human serum albumin incorporating the radioactivity and carbonized microspheres are suggested as potential carriers of isotopes for human radiation synovectomy.