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 intervals, the bone blocks containing the bone tunnels were isolated and processed for histologic examination. At the bone-bone interface, incorporation 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, consisting of four distinct zones, was observed without apparent necrotic and degenerative change for as long as 12 weeks. Between the tendon and the bone tunnel, a layer of hypercellular fibrous tissue gradually became mature with time. Thus, it appeared the morphologic characteristics and location of the reestablished attachment of the bone-patellar tendon-bone graft were more similar to those of the native anterior cruciate ligament compared with the graft to bone healing in the hamstring tendon graft.