Graft incorporation within the tibial bone tunnel after anterior cruciate ligament reconstruction with bone-patellar tendon-bone autograft

We described histologic changes in patellar tendon autografts that occur over time within the tibial tunnel in specimens harvested from patients undergoing revision anterior cruciate ligament reconstruction. Ten patients, averaging 21.2 years of age, were divided into two groups based on the time period between their original and revision surgery: early revision (less than 1 year, four patients) and late revision (more than 1 year, six patients). Among the early revision group, the tendon within the tunnel showed increased cellularity and random collagen bundles. A specimen from the shortest early revision case revealed a normal original bone-tendon junction, whereas others showed an obscured structure, Between the tendon and the tunnel wall, granulation tissue was seen and the bone-tendon junction was still immature. In the late revision group, the tendon appeared similar to normal ligament. The original bone-tendon junction was not seen, and the tendon continued completely to the tunnel wall with Sharpey-like fibers. Observations in the early revision group suggest that tendon remodeling and bone-tendon integration continue for at least several months after transplantation. The original bone-tendon junction appears to have shifted to the proximal patellar tendon-tunnel wall junction with time. These findings are in agreement with prior animal studies.