Repair of the lateral posterior meniscal root improves stability in an ACL-deficient knee

To investigate the stabilizing effect of a lateral meniscus posterior root repair in an ACL and root deficient knee.

The hypothesis of the current study was that a sequential transection of the posterior root and the meniscofemoral ligaments in an ACL-deficient knee increases rotational instability, and conversely, a repair of the meniscus root reduces the internal tibial rotation. Therefore, eight human knee joints were tested in a robotic setup (5 N m internal torque, 50 N m anterior translation load). Five conditions were tested: intact, ACL cut, ACL cut + lateral meniscus posterior root tear (LMRT), ACL cut + LMRT + transection of the MFL and ACL cut + lateral meniscus root repair. The angles of internal tibial rotation as well as anterior tibial translation were recorded.

Transection of the lateral meniscus posterior root increased the internal tibial instability as compared to the ACL-insufficient state. A significant increase was detected in 60° and 90° of flextion. Sectioning of the meniscofemoral ligament further destabilized the knees significantly at all flexion angles as compared to the ACL-deficient state. Even in 30°, 60° and 90° a significant difference was detected as compared to the isolated root tear. A tibial fixation of the lateral meniscus root reduced the internal tibial rotation in all flexion angles and led to a significant decrease of internal tibial rotation in 30° and 90° as compared to the transection of the root and the MFL. The anterior tibial translation was increased in all conditions as compared to the native state.

A lateral meniscus root repair can reduce internal tibial rotation in the ACL-deficient knee. To check the condition of the lateral posterior meniscus root attachment is clinical relevant as a lateral meniscus root repair might improve rotational stability.