Transplantation of the Rabbit's Patella*

Cartilage, unlike most other tissues, is capable of withstanding the immuno logical assault moursted w'hen transplantation is performed between genetically dissimilar individuals. This distinctive property has been used to advantage in plastic reconstructive surgery but has not been as useful in orthsopaedic procedures. Thse j)artial successes achieved by Lexer n6,n7ins man and Judet 12,13in animals in transsplarstinig articular cartilage have riot been sufficiently improved on to warrant full-scale clinsical applications. Despite refinements in technique, uniform success has nenssainied elusive. This study was undertaken to develop a model for the study of transplantation of an'ticular cartilage to clarify the factors irsfluenscing success or failure. Material and Methods Adult Xei@'Zealand rabbits, four monthss old and weighing between three and four kilograms, were individually caged and fed a commercial pellet diet, lettuce, and ivater ad libituin. Those rabbits which were used to study the effects of immuno suppressive drugs were given azathioprine by mouth through a syringe. Each of thsese animals received five milligrams per kilogram of body weight five days a w'eek commencing one week prior to transplantations of the patella. The peripheral w'hite blood count was monitored eachs week. Although there was some variation, most ansimals hsad white blood counts ins the normal range. The lowest count ob served si'as 3,000 white blood cells per cubic millimeter. Surgical Techniques Transplantation of the Patella Aninsals were anesthetized with intraperitoneal sodium pentobarbital, twenty five nsilligrams per kilogram of body weight supplemented by local infiltration of the operative site w'ith 1 per cent procaine. Under thse usual sterile precautions, the righst l)atell