Importance of the Medial Meniscus in the Anterior Cruciate Ligament-deficient Knee

Abstract

Summary:The incidence of meniscal tears in the chronically anlcrior cruciate ligament-deficient knee is increased, particularly in the medial meniscus becausc it performs an important function in limiting knee motion. We evaluated the role of the medial meniscus in stabilizing the anterior cruciate ligament-deficient knee and hypothesized that the resultant force in the meniscus is significantly elevated in the anterior cruciate liganienl-deficient knee. To test this hypothesis, we employed a robotic/universal force-moment sensor testing system to determine the increasc in the resultant force in the human medial meniscus in response to an anterior tibial load following transection of the anterior cruciate ligament. We also measured changes in the kinematics of the knee in multiple degrees of freedom following medial meniscectomy in the anterior cruciate ligament-deficient knee. In response to a 134-N anterior tibial load, the resultant force in the medial meniscus of the anterior cruciate ligament-deficient knee increased sign antly compared with that in the meniscus of the intact knee; it increased by a minimum of 10.1 N (52%) at full knee extension to a maximum of 50.2 N (197%) at 60" of flexion. Mcdial meniscectomy in the anterior cruciate ligament-deficient knee also caused a significant increase in anterior tibial translation in response to the anterior tibial load. ranging Prom an increase of 2.2 mm at full knee extension to 5.8 mm at 60" of flexion. Conversely. coupled internal tibial rotation in response to the load decreased significantly, ranging from a decrcase of 2.5" at 15" of knee flexion to 4.7" a1 hO* of flexion. Our data confirm the hypothesis that the resultant forcc in thc medial meniscus is significantly greater in the anterior cruciate ligament-deficient knee than in the intact knee when the knee is subjected to anterior tibial loads. This indicates that the demand on the medial meniscus in resisting anterior tibial loads is increased in the anterior cruciale ligament-deficient knee compared with in thc intact knee, suggesting a mechanism for the increased incidence of niedial meniscal tears observed in chronically anterior cruciale ligament-deficient patients. The large changes in kinematics due to medial meniscectomy in the anterior cruciate ligament-deficient knee confirm the important role of the mcdial meniscus in controlling knee stability. These findings sugeest that the reduction of resultant forcc in the meniscus may be a further motive for reconstructing the anterior cruciate ligament. with the goal of preserving meniscal integrity.

Relationship between increased in vivo meniscal loads and abnormal tibiofemoral surface alignment in ACL deficient sheep is varied

“…Results of this previous work support the accepted paradigm that menisci function as secondary restraints to anterior tibial translation, and may be at greater risk of injury due to larger load magnitudes following ACL injury (Allen, et al, 2000;Musahl, et al, 2010;Wieser, et al, 2011).…”

“…In contrast to existing studies that have investigated the load bearing function of menisci at discrete flexion angles within simulated or passive motion paths (Allen, et al, 2000;Papageorgiou, et al, 2001), our data are based on subject-specific in vivo joint kinematics for an actual gait stride. Given that we have previously shown that perturbations of only 0.5mm in subject-specific gait paths can increase tissue loads by up to 100% (Atarod, et al, 2014b;Darcy, et al, 2007), we believe that using subject-specific in vivo motion as input to our mechanical testing platform is critically important if are to quantify in vivo meniscal function accurately.…”

“…By and large, in vitro (Allen, et al, 2000;Papageorgiou, et al, 2001) and numerical (Li, et al, 2002) studies have provided significant evidence to support the hypothesis. In vitro robotic studies in particular have demonstrated that the medial collateral ligament (MCL) and menisci function as secondary restraints to anterior tibial translation during a simulated motion path (Allen, et al, 2000;Kanamori, et al, 2000).…”

“…By and large, in vitro (Allen, et al, 2000;Papageorgiou, et al, 2001) and numerical (Li, et al, 2002) studies have provided significant evidence to support the hypothesis. In vitro robotic studies in particular have demonstrated that the medial collateral ligament (MCL) and menisci function as secondary restraints to anterior tibial translation during a simulated motion path (Allen, et al, 2000;Kanamori, et al, 2000). Menisci also play a critical role in distributing contact stress uniformly between the tibiofemoral surfaces of the knee (Shrive, et al, 1978) and in modulating fluid flow within the load-bearing cartilage regions (Adeeb, et al, 2004).…”

Dynamic Contact Mechanics of the Medial Meniscus as a Function of Radial Tear, Repair, and Partial Meniscectomy

“…The wedge-shaped menisci increase the congruity between the convex femur and the relatively flat tibia and thereby protect the articular cartilage from excessive axial loads [1][2][3][4][5][6][7][8][9][10] . Radial meniscal tears are not uncommon in young patients 11 , and they often occur at the junction of the body and the posterior horn of the medial meniscus.…”