The Biomechanical Effect of a Lateral Meniscus Posterior Root Tear With and Without Damage to the Meniscofemoral Ligament: Efficacy of Different Repair Techniques

Purpose To evaluate the effect of the meniscofemoral ligament (MFL) in maintaining lateral-compartment contact pressures after injury to the posterior root of the lateral meniscus, and to measure the ability to restore intra-articular loads to normal by repairing the posterior root to the tibia after transection of the posterior root and the MFL. Methods Ten human cadaveric knee joints were axially loaded to 100 N. A digital pressure sensor measured the contact pressure in the lateral compartment. Five different conditions were tested: intact, after release of the posterior root of the lateral meniscus, after transection of the MFL along with release of the posterior root, refixation of the posterior root of the lateral meniscus to the tibia using an anatomic transosseous tunnel, and refixation of the root of the lateral meniscus using a tibial anterior cruciate ligament (ACL) tunnel. Results After transection of the posterior lateral meniscus root, the contact pressure did not increase significantly. The additional transection of the MFL led to a significant increase in the contact pressure. Anatomic fixation of the meniscus posterior horn reduced the femorotibial pressure to nearly pre-sectioning values. The reattachment of the meniscus posterior horn through a tibial ACL tunnel was equivalent to an anatomic fixation. Conclusions In the case of a root tear of the lateral meniscus, the MFL maintains meniscus function and stabilizes the pressure in the lateral compartment. A complete detachment of the posterior meniscus horn (MFL and root tear) leads to an increase in the intra-articular pressure. A root repair normalizes the pressure down to normal values. The tibial ACL tunnel is suitable to perform the repair and to lead out the suture. Clinical Relevance In the case of a complete detachment of the meniscus posterior horn, fixation of the posterior root is necessary to restore the meniscus function and to guarantee an equal pressure distribution in the lateral compartment. It can be combined with an ACL reconstruction. To evaluate the effect of the meniscofemoral ligament (MFL) in maintaining lateral-compartment contact pressures after injury to the posterior root of the lateral meniscus, and to measure the ability to restore intra-articular loads to normal by repairing the posterior root to the tibia after transection of the posterior root and the MFL. Ten human cadaveric knee joints were axially loaded to 100 N. A digital pressure sensor measured the contact pressure in the lateral compartment. Five different conditions were tested: intact, after release of the posterior root of the lateral meniscus, after transection of the MFL along with release of the posterior root, refixation of the posterior root of the lateral meniscus to the tibia using an anatomic transosseous tunnel, and refixation of the root of the lateral meniscus using a tibial anterior cruciate ligament (ACL) tunnel. After transection of the posterior lateral meniscus root, the contact pressure did not increase significantly. The additional transection of the MFL led to a significant increase in the contact pressure. Anatomic fixation of the meniscus posterior horn reduced the femorotibial pressure to nearly pre-sectioning values. The reattachment of the meniscus posterior horn through a tibial ACL tunnel was equivalent to an anatomic fixation. In the case of a root tear of the lateral meniscus, the MFL maintains meniscus function and stabilizes the pressure in the lateral compartment. A complete detachment of the posterior meniscus horn (MFL and root tear) leads to an increase in the intra-articular pressure. A root repair normalizes the pressure down to normal values. The tibial ACL tunnel is suitable to perform the repair and to lead out the suture.