Evaluation of the Leeds-Keio Synthetic Replacement for the Cranial Cruciate Ligament in Dogs: An Experimental Study

SummaryEight conditioned research dogs, whose body weight was between 25 and 30 kg, had unilateral implantation of a Leeds-Keio (LK) synthetic implant (Dacron polyester) immediately after severance and removal of the cranial cruciate ligament (CCL). A rectangular- shaped autograft, composed of fascia lata, was placed within the LK implant in four of the eight dogs; the other four dogs received the LK implant only. Modified Robert Jones bandages were placed on the limbs that had been operated upon; the bandages were left in place for 48 hours. After that time the limbs were not splinted. The dogs were confined to 1.5 m X 3 m kennels, with twice daily leash walks for the duration of the study. Although the joints that received the LK implants were stable immediately after the operation, they all developed progressive effusion, crepitation and instability accompanied by clinically apparent lameness. All of the dogs were euthanatized three months after the operations. Gross examination of the eight joints that had been operated upon confirmed the presence of degenerative joint disease. Three of the eight dogs had “bucket handle” type tears of their medial meniscus in the joints with the LK implant, and the medial menisci in the other five stifle joints that received LK implants had a fibrillated surface texture. Five of the eight LK implants had either ruptured completely or were stretched and frayed to the point where mechanical testing was not justified. Mean breaking strength of the 3 intact LK implants was 6.6% of the contralateral, control CCL. Ingrowth of fibrous tissue into the LK implants was minimal. The synovium from all joints with LK implants had moderate to severely increased cellularity within the synovial villi and supporting stroma consisting predominantly of lymphocytes, plasma cells and macrophages. Multinucleated giant cells formed aggregates around irregular shaped strands of particulate material which was translucent and refractive. Under polarized light, these particles were bright yellow to green consistent with Dacron particles. It was concluded that the LK implant, as implanted in this study, was not a satisfactory replacement for the CCL in dogs.The Leeds-Keio synthetic replacement for the canine cranial cruciate ligament was implanted in eight dogs. All eight dogs developed progressive instability and secondary degenerative joint disease over a period of three months after the operation. It was concluded that the Leeds-Keio ligament, as implanted in this study, is not satisfactory for use in dogs.