In 28 laboratory animals were implanted micro total prostheses prepared fl'om original alloplastic Mueller-Charnley total hip joint prostheses.
This series of experiments should primarily have given information about reaction of the rat organism to the products of abrasion from alloplastic joint unit. This goal could not be attained: after primary wound healing and the initial good functioning of the alloplasty, loosening of the prostheses occured. Loosening with succeeding dislocation could be demonstrated, at the latest, 4 weeks after the operation in all the experimental animals. In spite of this occurenee the animals were not destroyed, but further observed. This revealed that, at the earliest, 8 weeks and at the latest, 12 months after the operative intervention, osteomyelitis with fistula suppuration, in some cases with spontaneous separation of the prosthetic head, broke out; otherwise several animals with ileus symptoms died from changes radiologically identifiable as osteomyelitis without fistula in the operated femur.
The experiment c~me to an end due to the electrogenetic activity of the loosened metallic implant and to the reaction of the rat organism to a too large foreign body.