Quantifying the differential functional behavior between the medial and lateral meniscus after posterior meniscus root tears

Abstract

Meniscus tears of the knee are among the most common orthopedic knee injury. Specifically, tears of the posterior root can result in abnormal meniscal extrusion leading to decreased function and progressive osteoarthritis. Despite contemporary surgical treatments of posterior meniscus root tears, there is a low rate of healing and an incidence of residual meniscus extrusion approaching 30%, illustrating an inability to recapitulate native meniscus function. Here, we characterized the differential functional behavior of the medial and lateral meniscus during axial compression load and dynamic knee motion using a cadaveric model. We hypothesized essential differences in extrusion between the medial and lateral meniscus in response to axial compression and knee range of motion. We found no differences in the amount of meniscus extrusion between the medial and lateral meniscus with a competent posterior root (0.338mm vs. 0.235mm; p-value = 0.181). However, posterior root detachment resulted in a consistently increased meniscus extrusion for the medial meniscus compared to the lateral meniscus (2.233mm vs. 0.4705mm; p-value < 0.0001). Moreover, detachment of the posterior root of the medial meniscus resulted in an increase in extrusion at all angles of knee flexion and was most pronounced (4.00mm ± 1.26mm) at 30-degrees of knee flexion. In contrast, the maximum mean extrusion of the lateral meniscus was 1.65mm ± 0.97mm, occurring in full extension. Furthermore, only the medial meniscus extruded during dynamic knee flexion after posterior root detachment. Given the differential functional behaviors between the medial and lateral meniscus, these findings suggest that posterior root repair requires reducing overall meniscus extrusion and recapitulating the native functional responses specific to each meniscus.

Repair of meniscus root tear – Is there a difference between medial meniscus root repair and lateral meniscus root repair? A systematic review and meta-analysis

“…Concerning the change in meniscus extrusion after surgery, the pooled figure for the medial side was +0.2 mm, and that of the lateral side was À1.2 mm. Furthermore, a biomechanical study by Walczak et al 10 reported that there were no differences in the amount of meniscus extrusion between the medial and lateral meniscus in the presence of a competent posterior root (0.338 mm vs 0.235 mm; p = 0.181). However, upon inducing posterior root detachment in both roots, the medial meniscus had consistently increased amounts of meniscus extrusion compared to the lateral meniscus (2.233 mm vs 0.471 mm; p < 0.0001).…”

“…Many of them also suffered from concomitant anterior cruciate ligament injury. 10 A discrepancy can also be seen between the reported preoperative meniscal extrusion between medial root tears (3.77 mm) 11 and lateral meniscus root tears (0.73 mm). 12 However, it remains unknown whether the anatomical differences between the medial and lateral meniscus lead to the differences seen above.…”

“…3 Differences in the presentation of medial and lateral meniscus root tears can be observed. 9,10,11,12 Patients presenting with medial meniscus root tear are often middleaged and elderly subjects; the cause of the tear is believed to be degenerative in origin. 9 On the other hand, the etiology of lateral meniscus root tear is often traumatic in origin.…”

Association of Increased Lateral Femoral Condylar Ratio With Lateral Meniscus Posterior Root Tear in Noncontact ACL Injury

“…Although biomechanical properties have been investigated extensively for the root tear of the medial meniscus, there is a paucity of literature concerning biomechanical evaluation of LMPRTs. Walczak et al 22 investigated functional behavior of the lateral meniscus during axial compression load and dynamic knee motion. Posterior root detachment of the lateral meniscus resulted in a maximum extrusion of 1.65 6 0.97 mm in full extension.…”