Various surgical procedures for ACL reconstruction (intraarticular, extraarticular, and combined procedures) were performed on ACL-sectioned anatomic knee specimens, and their effects on tibial rotation were investigated by analyzing knee movements under valgus and rotatory torques on five fresh anatomic knee specimens. The movements were measured in three dimensions using biplanar photography, when all the ligaments were intact, then after the ACL was sectioned, and finally after each surgical procedure was performed. From the results, the pivot shift, which had been observed when the ACL was sectioned, disappeared after carrying out any of the procedures examined. On the other hand, the range of physiologic rotation of the tibia reduced to less than its normal value when either the extraarticular reconstruction or the combined reconstructive procedure was performed. However, the tibial rotation was restored to almost its normal value when the intraarticular reconstruction was performed. Thus, it would appear that the intraarticular reconstruction of the ACL is the best way for eliminating the pivot shift and restoring the joint mechanics to normality.