Clinical and radiographic results of ACL reconstruction: a 5-to 7-year follow-up study of outside-in versus inside-out reconstruction techniques

This study compared the clinical outcome of anterior cruciate ligament (ACL) reconstruction between the inside-out and the outside-in techniques and assessed radiographically whether surgical technique affects the position and direction of the bone tunnels. A patellar tendon ACL reconstruction was performed in 141 patients with inside-out (group I, n=78) and outside-in technique (group Ii, n=63). Clinical results were evaluated using the International Knee Documentation Committee (IKDC) form; radiographic study was performed in anteroposterior, lateral, and notch views. Overall results in group I were normal in 23% of cases, nearly normal in 55%, and abnormal in 22%; in group II there were normal results in 19% of cases, nearly normal in 57%, abnormal in 19%, and severely abnormal in 5%. Radiographic examination identified important differences between the two groups. The main differences between the two surgical techniques were related to the positioning of the femoral tunnel. With the inside-out technique the femoral tunnel was significantly more vertical, both in the frontal and the sagittal planes. Moreover, the femoral tunnel was higher when drilled from the inside, but the difference between the two techniques was not statistically significant. The differences found between the two techniques regarding the tibial tunnel were not significant, although in the inside-out group the tibial tunnel seemed slightly more lateral, vertical, and posterior. Moreover, we observed a greater risk of bone-screw divergence on the femur in the inside-out group. This divergence was greatest in the sagittal plane. However, we observed no effect of this bone-screw divergence on the stability of the knee at followup.