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.