Effect of femoral tunnel placement for reconstruction of the anterior cruciate ligament on tibial rotation.

BACKGROUND Rotational knee movement after reconstruction of the anterior cruciate ligament has been difficult to quantify. The purpose of this study was to identify in vivo whether a more horizontal placement of the femoral tunnel (in the ten o'clock position rather than in the eleven o'clock position) can restore rotational kinematics, during highly demanding dynamic activities, in a knee in which a bone-patellar tendon-bone graft had been used to reconstruct the anterior cruciate ligament. METHODS We evaluated ten patients in whom a bone-patellar tendon-bone graft had been used to reconstruct the anterior cruciate ligament with the femoral tunnel in the eleven o'clock position, ten patients who had had the same procedure with the femoral tunnel in the ten o'clock position, and ten healthy controls. Kinematic data were collected while the subjects (1) descended from a stairway, made foot contact, and then pivoted 90 degrees on the landing lower limb and (2) jumped from a platform, landed with both feet on the ground, and pivoted 90 degrees on the right or left lower limb. The dependent variable that we examined was tibial rotation during pivoting. RESULTS The results demonstrated that reconstruction of the anterior cruciate ligament with the femoral tunnel in either the ten or the eleven o'clock position successfully restored anterior tibial translation. However, both techniques resulted in tibial rotation values, during the dynamic activities evaluated, that were significantly larger than those in the intact contralateral lower limbs and those in the healthy controls. Tibial rotation did not differ significantly between the two reconstruction groups or between the healthy controls and the intact contralateral lower limbs. However, we noticed that positioning the tunnel at ten o'clock resulted in slightly decreased rotation values that may have clinical relevance but not statistical significance. CONCLUSIONS Regardless of which of the two tested positions was utilized to fix the graft to the femur, reconstruction of the anterior cruciate ligament did not restore normal tibial rotation during dynamic activities.