Graft healing in the bone tunnel in anterior cruciate ligament reconstruction

The histologic sequence in the bone tunnel after anterior cruciate ligament reconstruction using the bone-patellar tendon-bone graft was investigated in this study. Eighteen adult mongrel dogs were used. After excision of the anterior cruciate ligament, the graft was routed through the bone tunnels and fixed with interference fit screws. After the dogs were sacrificed at i ntervals, the bone blocks containing the bone tunnels were isolated and pro cessed for histologic examination. At the bone-bone interface, incorporatio n of the bone plug at each end of the graft was completed at 12 weeks. The structure of the tendon insertion of the grafted patellar tendon, consistin g of four distinct zones, was observed without apparent necrotic and degene rative change for as long as 12 weeks. Between the tendon and the bone tunn el, a layer of hypercellular fibrous tissue gradually became mature with ti me. Thus, it appeared the morphologic characteristics and location of the r eestablished attachment of the bone-patellar tendon-bone graft were more si milar to those of the native anterior cruciate ligament compared with the g raft to bone healing in the hamstring tendon graft.