A comparative study of the length patterns of anterior cruciate ligament reconstructions in the dog and man

Objective: To measure the change of length patterns of nine different simul ated anterior cruciate ligament (ACL) reconstructions in the canine and hum an knee. Procedures: Six fresh-frozen canine cadaver knees and six fresh-fr ozen human cadaver knees were used in this study. All of the soft tissues w ere removed from each cadaver knee, leaving the menisci, collateral ligamen ts and cruciate ligaments intact. After fixation of the femur to a custom-m ade frame, the ACL was excised. Three tunnels were made each at the ACL ori gin and insertion, making possible nine reconstruction combinations. A modi fied intra-articular technique was used to measure change of length, in mm, of each ACL reconstruction through a range of motion of 0 degrees (full ex tension) to 135 degrees of flexion. A rank-order list of reconstruction com binations was determined. The most isometric combination was determined for the canine and human knees, and trends in length patterns were also evalua ted in both species relative to femoral and tibial position. Statistical si gnificance was determined by ANOVA. Results: A combination joining a point caudal to the ACL origin (over-the-top) and anterior on the tibial insertio n was found to be the most isometric combination in both the canine and hum an. The trends in change of length patterns across all reconstruction combi nations were similar in the dog and man. Isometry was improved as the recon struction was placed further posterior on the femur and anterior on the tib ia. Conclusions: The canine knee is an appropriate animal model for the stu dy of isometry of the human ACL and its reconstructions.