Acute cell viability and nitric oxide release in lateral menisci following closed-joint knee injury in a lapine model of post-traumatic osteoarthritis

BACKGROUND: Traumatic impaction is known to cause acute cell death and macroscopic damage to cartilage and menisci in vitro. The purpose of this study was to investigate cell viability and macroscopic damage of the medial and lateral menisci using an in situ model of traumatic loading. Furthermore, the release of nitric oxide from meniscus, synovium, cartilage, and subchondral bone was also documented. METHODS: The left limbs of five rabbits were subjected to tibiofemoral impaction resulting in anterior cruciate ligament (ACL) rupture and meniscal damage. Meniscal tear morphology was assessed immediately after trauma and cell viability of the lateral and medial menisci was assessed 24 hrs post-injury. Nitric oxide (NO) released from joint tissues to the media was assayed at 12 and 24 hrs post injury. RESULTS: ACL and meniscal tearing resulted from the traumatic closed joint impact. A significant decrease in cell viability was observed in the lateral menisci following traumatic impaction compared to the medial menisci and control limbs. While NO release was greater in the impacted joints, this difference was not statistically significant. CONCLUSION: This is the first study to investigate acute meniscal viability following an in situ traumatic loading event that results in rupture of the ACL. The change in cell viability of the lateral menisci may play a role in the advancement of joint degeneration following traumatic knee joint injury. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/1471-2474-15-297) contains supplementary material, which is available to authorized users

Identification of Cross-Sectional Parameters of Lateral Meniscal Allografts That Predict Tibial Contact Pressure in Human Cadaveric Knees

To guide the development of improved procedures for selecting meniscal allografts, the objective of this study was to identify which cross-sectional parameters of a lateral menisca

3D finite element model of meniscectomy: Changes in joint contact behavior

The goal of this study is to quantify changes in knee joint contact behavior following varying degrees of the medial partial meniscectomy. A previously validated 3D finite element model was used to simulate 11 different meniscectomies. The accompanying changes in the contact pressure on the superior surface of the menisci and tibial plateau were quantified as was the axial strain in the menisci and articular cartilage. The percentage of medial meniscus removed was linearly correlated with maximum contact pressure, mean contact pressure, and contact area. The lateral hemi-joint was minimally affected by the simulated medial meniscectomies. The location of maximum strain and location of maximum contact pressure did not change with varying degrees of partial medial meniscectomy. When 60% of the medial meniscus was removed, contact pressures increased 65% on the remaining medial meniscus and 55% on the medial tibial plateau. These data will be helpful for assessing potential complications with the surgical treatment of meniscal tears. Additionally, these data provide insight into the role of mechanical loading in the etiology of post-meniscectomy osteoarthritis. Copyright © 2006 by ASME

Role of cell location and morphology in the mechanical environment around meniscal cells

Fibrochondrocytes within meniscal tissue have been shown to alter their biochemical activity in response to changes in their mechanical environment. Meniscal tissue is known to contain both spherical (chondrocytic-like) and elliptical (fibroblastic-like) cells. We hypothesize that a cell\u27s mechanical environment is governed by local material properties of the tissue around the cell, the cell morphology and the cell\u27s position within the tissue. A two-dimensional, non-linear, fiber (collagen) reinforced, multi-scale, finite element model was utilized to quantify changes in the stress, strain, fluid velocity and fluid flow induced shear stress (FFISS) within and around fibrochondrocytes. Cells differing in morphology and size were modeled at different locations within an explant 6 mm in diameter and 5 mm thick, under 5% unconfined compression. Cellular stresses were an order of magnitude less than surrounding extracellular matrix stresses but cellular strains were higher. Cell size affected both the stress and strain levels within the cell, with smaller cells being exposed to smaller principal stresses and strains than larger cells of the same shape. The pericellular matrix of an elliptical cell was less effective at shielding the cell from large principal strains and stresses. FFISS were largest around small circular cells (∼0.13 Pa), and were dramatically affected by the position of the cell relative to the axis of the explant, with cells closer to the periphery experiencing greater FFISS than cells near the central axis of the explant. These results will allow biosynthetic activity of fibrochondrocytes to be correlated with position and morphology in the future. © 2006 Acta Materialia Inc

From meniscus to bone: A quantitative evaluation of structure and function of the human meniscal attachments

Meniscus efficacy at promoting joint congruity and preventing osteoarthritis hinges on enthesis integrity. Gross-scale tensile testing, histomorphometry and magnetic resonance imaging reveal significant differences between the four attachments, implying that each must endure a unique mechanical environment, which dictates their structure. However, little data exists to elucidate how these interfaces have adapted to their complex loading environment, particularly on a relevant scale, as the enthesis transitions through several unique zones in less than a millimeter. In our study we leveraged nanoindentation to determine viscoelastic material properties through the transition zones. Additionally, we employed histological techniques to evaluate the enthesis structure, including collagen organization and interdigitation morphometry. Mechanical evaluation revealed the medial posterior insertion site to be significantly more compliant than others. Collagen fiber orientation and dispersion as well as interdigitation morphometry were significantly different between attachments sites. These findings are clinically relevant as a disproportionate amount of enthesis failure occurs in the medial posterior attachment. Also, meniscal enthesis structure and function will need to be considered in future reparative and replacement strategies in order to recreate native meniscus mechanics and prevent osteoarthritis propagation. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved

Osteoarthritic meniscal entheses exhibit altered collagen fiber orientation

Purpose/Aim: The knee menisci are vital for maintaining the stability of the joint, allowing for force distribution, and protecting the underlying articular cartilage during loading. Each meniscus is attached to the underlying bone via two ligamentous entheses composed of collagen fibers that are continuous throughout all four zones of the attachment: ligament, uncalcified fibrocartilage, calcified fibrocartilage, and subchondral bone. The collagen fibers of the meniscal entheses are important for proper functionality of the entheses, particularly in preventing meniscal extrusion which is a common hallmark of osteoarthritis. The goal of this work was to assess changes in collagen fiber orientation present in osteoarthritic knee joints. Materials and Methods: Entheses were harvested from patients undergoing total knee arthroplasties and prepared histological sections were stained with picrosirius red to identify collagen fiber angle and fiber deviation. Results: In the calcified fibrocartilage the collagen fibers of the lateral anterior enthesis inserted at significantly (p \u3c 0.1) shallower angles, and the fiber deviation was significantly (p \u3c 0.1) less compared to the lateral posterior enthesis. These differences in the calcified fibrocartilage may occur as an adaptation to loading regimes of the osteoarthritic joint. When compared to the collagen fiber orientation of healthy entheses, collagen fibers in osteoarthritic tissue inserted at shallower insertion angles and demonstrated higher levels of deviation. Conclusions: Changes to meniscal enthesis collagen fiber orientation with end stage osteoarthritis could offer an explanation for the change in functionality of diseased tissue and may contribute to meniscal extrusion and ultimately the degeneration of articular cartilage

A study of collagen crimp pattern in the bovine anterior and posterior medial meniscal horn attachments

Menisci are fibrocartilagenous structures located between the femoral condyles and tibial plateau that aid in joint lubrication and stability in the knee joint. Previous experimental and theoretical studies have shown that the meniscal horn attachments, which serve as the transition from mensical fibrocartilage into subchondral bone, are important for proper meniscal function [1–3]. Meniscal attachments did not show significant differences in surface mechanical properties such as ultimate strain or moduli, however, there were significant differences in overall behavior of the anterior versus posterior attachments [4]. No significant differences in creep or stress relaxation properties were found between the different meniscal attachments [5].</jats:p

Role of IL-1 on aggrecanase and COX-2 gene expression of meniscal explants following dynamic compression

The menisci within the knee likely respond to adverse loading conditions, leading to aggravated cartilage damage and fissuring [1]. Upregulation of catabolic molecules such as interleukin-1α (IL-1α), metalloproteinases (MMPs), aggrecanases (ADAMTS-4 and -5), and cyclooxygenase-2 (COX-2), as well as release of proteoglycans [2], have been shown in vitro for meniscal explants following dynamic loading [3]. A crucial event in matrix degradation is the loss of aggrecan, caused by the ADAMTS family [4]. In osteoarthritic cartilage, IL-1 has been shown to influence COX-2 activity, leading to increased synthesis of prostaglandin E2 and subsequent proteinase activity [5].</jats:p