Forces at the Anterior Meniscus Attachments Strongly Increase Under Dynamic Knee Joint Loading

Abstract

Background: The anatomic appearance and biomechanical and clinical importance of the anterior meniscus roots are well described. However, little is known about the loads that act on these attachment structures under physiological joint loads and movements. Hypotheses: As compared with uniaxial loading conditions under static knee flexion angles or at very low flexion-extension speeds, more realistic continuous movement simulations in combination with physiological muscle force simulations lead to significantly higher anterior meniscus attachment forces. This increase is even more pronounced in combination with a longitudinal meniscal tear or after total medial meniscectomy. Study Design: Controlled laboratory study. Methods: A validated Oxford Rig–like knee simulator was used to perform a slow squat, a fast squat, and jump landing maneuvers on 9 cadaveric human knee joints, with and without muscle force simulation. The strains in the anterior medial and lateral meniscal periphery and the respective attachments were determined in 3 states: intact meniscus, medial longitudinal tear, and total medial meniscectomy. To determine the attachment forces, a subsequent in situ tensile test was performed. Results: Muscle force simulation resulted in a significant strain increase at the anterior meniscus attachments of up to 308% ( P < .038) and the anterior meniscal periphery of up to 276%. This corresponded to significantly increased forces ( P < .038) acting in the anteromedial attachment with a maximum force of 140 N, as determined during the jump landing simulation. Meniscus attachment strains and forces were significantly influenced ( P = .008) by the longitudinal tear and meniscectomy during the drop jump simulation. Conclusion: Medial and lateral anterior meniscus attachment strains and forces were significantly increased with physiological muscle force simulation, corroborating our hypothesis. Therefore, in vitro tests applying uniaxial loads combined with static knee flexion angles or very low flexion-extension speeds appear to underestimate meniscus attachment forces. Clinical Relevance: The data of the present study might help to optimize the anchoring of meniscal allografts and artificial meniscal substitutes to the tibial plateau. Furthermore, this is the first in vitro study to indicate reasonable minimum stability requirements regarding the reattachment of torn anterior meniscus roots.

Increased Posterior Tibial Slope Increases Force on the Posterior Medial Meniscus Root

“…Previous studies have evaluated 1-dimensional PMMR forces in the setting of an ACL-deficient knee or during normal knee loading. 22,32,33,35 However, this study has demonstrated that, to stabilize the knee, the reaction forces in the PMMR are variable and multiaxial. Any assessment of the forces at the PMMR should include measurement of forces in all directions.…”

Free‐floating medial meniscus implant kinematics do not change after simulation of medial open‐wedge high tibial osteotomy and notchplasty

“…Third, the MOWHTO was not surgically performed in vitro but simulated by adjusting the leg alignment by an altered CCD angle that resulted in a 10° valgus shift of the knee joint angle. Due to the combination of a slightly compromised stability of the knee joint, which was induced by soft tissue removal, and the high mechanical loads that result in realistic tibiofemoral contact pressures [39] that are applied to the knee joints could have led to lateral hinge fractures after MOWHTO surgery. In addition, it would not have been possible to clearly determine the cause of the obtained results, because the surgical interventions of the MOWHTO and the notchplasty could potentially influence each other.…”

“…This could be mainly attributed to the joint gap widening, and to the concurrently reduced contact pressure on the medial compartment, which appears to move the NUsurface ® device more compared to the normal leg alignment conditions [43]. The used knee joint simulator is able to perform dynamic loading situations on cadaveric knee joints that result in physiological tibiofemoral contact pressures [39]. Therefore, the contact pressure between the femur and tibia as well as the resulting contact transmission of the device in the present study could be assumed to be adequate.…”

“…An Oxford‐rig knee simulator, which allowed physiological replication of the whole leg, including the hip joint with an adjustable caput‐collum‐diaphyseal ( CCD ) angle , femur, tibia and ankle joint, was used to perform dynamic exercises on cadaveric knee joints [37, 39] while providing all physiological degrees of freedom. Prior to testing, a pilot trial on one additional cadaveric knee joint confirmed that the removal of skin, subcutaneous fat and muscles did not affect the outcome measures.…”

A Tough Biointerface in Human Knee Empowered by Dynamic Phase-transforming Minerals in Collagenous Matrix

“…1A). Meniscus root bears tension up to 200 N with a 20 mm 2 cross-sectional area 13,14 , in which the stress is comparable to using a single hand to lift a five-ton truck. The demanding mechanical loading regime drives the root-bone interface to evolve into an extremely tough, fatigue-resistant soft-hard transitional structure.…”