A multidisciplinary study of the healing of an intraarticular anterior cruciate ligament graft in a goat model

We evaluated knee function, tensile properties, and histologic appearance o f a healing intraarticular bone-patellar tendon-bone autograft after anteri or cruciate ligament reconstruction in a goat model. The patellar tendon gr aft was fixed such that both bone-to-bone (femoral tunnel) and bone-to-tend on (tibial tunnel) healing could be studied. The total anteroposterior tran slation significantly increased from 3 to 6 weeks, ranging from increases o f 28.8% to 46.7%. In situ forces in the replacement graft decreased as much as 22.2% at 6 weeks. Conversely, tensile properties of the femur-anterior cruciate ligament graft-tibia complex did not change significantly from 3 t o 6 weeks. However, the mode of failure changed from the graft pulling out of the tibial tunnel at 3 weeks to a mix of midsubstance failures (N=2) and pullouts (N=5) at 6 weeks. Histologic evaluations revealed progressive and complete incorporation of the bone block in the femoral tunnel, but only p artial incorporation of the tendinous part of the graft in the tibial tunne l. The differences demonstrated at 3 and 6 weeks may be a result of the rem odeling process of the midsubstance of the graft as the interfaces within t he osseous tunnels mature.