The Current Knowledge in Tibial Translatory Movements in ACL-Deficient Knees: A Review of the Literature

The anterior cruciate ligament (ACL) is known as the main restraint of anterior tibial translation of the knee joint during movements. Loss of the ACL disrupts the delicate balance of knee structures and may lead to knee joint instability. This, in turn, may cause further damage to the knee structures. Because of the complexity of the knee joint, the movements of the tibia relative to the femur is not a simple anterior-posterior motion and there is a serious controversy in literature in measurement of tibial translatory amounts relative to the femur. This is mainly due to the existence of a semi-circular locus (and not a simple trans-condylar axis) of the instant centre in the knee joint. Occurring tibial translatory movement simultaneously with its rotary movement is another issue that makes measurement of this motion very hard. This study aimed to review the current methods of measurements of tibial translatory motion in ACLdeficient and normal knees. It was concluded that finding an accurate and non-invasive method to analyse tibial movement relative to the femur in vivo situations is very difficult and all of the available procedures have their own inherent limitations. It was also recommended that some new non-invasive methods using optic/optoelectronic devices should be considered to provide the most accurate data during in vivo tasks.