Graft tension in anterior cruciate ligament reconstruction. An in vivo study in dogs.

The purpose of this study was to examine the effect of initial tensioning on the outcome of reconstruction of the ACL. The ACLs of 15 adult mongrel dogs were excised and reconstructed. In the first five dogs, the ACLs of both knees were reconstructed using the medial one-third of the patellar tendon. The graft was fixed under a tension of 1 N (0.22 pounds) in one knee and 39 N (8.8 pounds) in the opposite knee. In the remainder of the dogs, the reconstructions were augmented with Dacron prostheses. Tensioning of both graft components in the augmented reconstructions was either with 1 N in one knee and 39 N in the contralateral knee or disproportionate tensions of 1 N and 39 N applied to the autogenous material and to the prosthesis. Sacrifice was 3 months postsurgery and results were examined with microangiography/history and mechanical testing. In the reconstructions with the patellar tendon alone, the biologic study showed poor vascularity and focal myxoid degeneration within the graft pretensioned with a load of 39 N. In the augmented reconstructions, the knees in which both graft materials were fixed with 1 N tension showed the strongest and stiffest reconstruction at 3 months. The study suggests that minimal tension should be applied to the graft materials during surgical reconstruction of the ACL.