Comparison of over-the-top and tunnel techniques for anterior cruciate ligament replacement.

The osseous tunnel technique of anterior cruciate ligament (ACL) reconstruction was compared to the over-the-top (OTT) technique in vivo. A prosthesis replaced the ACL in 35 dogs by one of three methods: double osseous tunnels, OTT, or a combined method utilizing the unique Y shape of the prosthesis by placing one fork through a femoral osseous tunnel and the other fork over the top of the femoral condyle in the same stifle. Rupture occurred in all prostheses placed in double osseous tunnels and in one of 12 prostheses placed by the OTT technique. When rupture occurred in only one fork of prostheses placed in the combined method, all occurred in the tunnel-placed fork. If the results of the three groups are combined, rupture occurred in 16.7% of all OTT-placed prostheses versus 91.3% rupture of all osseous tunnel-placed prostheses. Objective assessment of the in vivo testing clearly indicates that the OTT technique is superior to the tunnel technique under the conditions of this study. The relationship between placement technique and rupture of other prostheses should also be tested in vivo.