Determination of graft tension before fixation in anterior cruciate ligament reconstruction

This study was performed to determine the tension needed to be applied on an anterior cruciate ligament graft before fixation to obtain normal anteroposterior translation following an anterior cruciate ligament reconstruction. Ten fresh-frozen cadaver knees underwent arthroscopy and were determined to have intact anterior and posterior cruciate ligaments and both menisci. A knee arthrometer (model KT 1000. MedMetric Corp., San Diego, CA, U.S.A.) was used to determine the anteroposterior translation with a 20 lb load. The anterior cruciate ligament was arthroscopically sectioned, and a repeat arthrometer measurement was made. Isometric points in the femur and tibia were determined using a tension isometer before drilling bony tunnels. The central third patellar tendon (bone-tendon-bone) complex, semitendinosus that was doubled on itself, and an iliotibial band approximately 3 cm wide were harvested. The grafts were separately passed through the knee, the femoral end was secured, and various tensions were applied to the tibial end before fixation. Repeat knee arthrometer measurements were performed after each new tension was applied. Arthrometer testing was continued until the postreconstruction 20 lb anterior drawer equalled the anterior cruciate ligament intact drawer. The patellar tendon returned the knee to its preoperative condition with a mean 3.6 lb of tension, the semitendinosus with 8.5 lb. and the iliotibial band with 13.6 lb. All these differences were statistically significant (p less than 0.01). The tension that needs to be applied to a graft during an anterior cruciate ligament reconstruction appears to be tissue specific. It is hoped that precise intraoperative tensioning of anterior cruciate ligament grafts will lead to more reproducible anterior cruciate reconstruction results.