Evolution of Meniscal Biomechanical Properties with Growth: An Experimental and Numerical Study

Comparison of constitutive models for meniscus and their effect on the knee joint biomechanics during gait

Mechanical behavior of meniscus can be modeled using constitutive material models of varying complexity, such as isotropic elastic or fibril reinforced poroelastic (FRPE). However, the FRPE material is complex to implement, computationally demanding in 3D geometries, and simulation is time-consuming. Hence, we aimed to quantify the most suitable and efficient constitutive model of meniscus for simulation of cartilage responses in the knee joint during walking. We showed that simpler constitutive material models can reproduce similar cartilage responses to a knee model with the FRPE meniscus, but only knee models that consider orthotropic elastic meniscus can also reproduce meniscus responses adequately.

Biomechanics Assist Measurement, Modeling, Engineering Applications, and Clinical Decision Making in Medicine

Biomechanical studies of surgeries and medical devices are usually performed with human or animal models [...].

Identification of Kinetic Abnormalities in Male Patients after Anterior Cruciate Ligament Deficiency Combined with Meniscal Injury: A Musculoskeletal Model Study of Lower Limbs during Jogging

There is little known about kinetic changes in anterior cruciate ligament deficiency (ACLD) combined with meniscal tears during jogging. Therefore, 29 male patients with injured ACLs and 15 healthy male volunteers were recruited for this study to investigate kinetic abnormalities in male patients after ACL deficiency combined with a meniscal injury during jogging. Based on experimental data measured by an optical tracking system, a subject-specific musculoskeletal model was employed to estimate the tibiofemoral joint kinetics during jogging. Between-limb and interpatient differences were compared by the analysis of variance. The results showed that decreased knee joint forces and moments of both legs in ACLD patients were detected during the stance phase compared to the control group. Meanwhile, compared with ACLD knees, significantly fewer contact forces and flexion moments in ACLD combined with lateral and medial meniscal injury groups were found at the mid-stance, and ACLD with medial meniscal injury group showed a lower axial moment in the loading response (p < 0.05). In conclusion, ACLD knees exhibit reduced tibiofemoral joint forces and moments during jogging when compared with control knees. A combination of meniscus injuries in the ACLD-affected side exhibited abnormal kinetic alterations at the loading response and mid-stance phase.

Optimizing artificial meniscus by mechanical stimulation of the chondrocyte-laden acellular meniscus using ad hoc bioreactor

Background

Tissue engineering focuses on reconstructing the damaged meniscus by mimicking the native meniscus. The application of mechanical loading on chondrocyte-laden decellularized whole meniscus is providing the natural microenvironment. The goal of this study was to evaluate the effects of dynamic compression and shear load on chondrocyte-laden decellularized meniscus.

Material and methods

The fresh samples of rabbit menisci were decellularized, and the DNA removal was confirmed by histological assessments and DNA quantification. The biocompatibility, degradation and hydration rate of decellularized menisci were evaluated. The decellularized meniscus was injected at a density of 1 × 10⁵ chondrocyte per scaffold and was subjected to 3 cycles of dynamic compression and shear stimuli (1 h of 5% strain, ± 25°shear at 1 Hz followed by 1 h rest) every other day for 2 weeks using an ad hoc bioreactor. Cytotoxicity, GAG content, ultrastructure, gene expression and mechanical properties were examined in dynamic and static condition and compared to decellularized and intact menisci.

Results

Mechanical stimulation supported cell viability and increased glycosaminoglycan (GAG) accumulation. The expression of collagen-I (COL-I, 10.7-folds), COL-II (6.4-folds), aggrecan (AGG, 3.2-folds), and matrix metalloproteinase (MMP3, 2.3-folds) was upregulated compared to the static conditions. Furthermore, more aligned fibers and enhanced tensile strength were observed in the meniscus treated in dynamic condition with no sign of mineralization.

Conclusion

Compress and shear stimulation mimics the loads on the joint during walking and be able to improve cell function and ultrastructure of engineered tissue to recreate a functional artificial meniscus.

Meniscus Matrix Structural and Biomechanical Evaluation: Age-Dependent Properties in a Swine Model

The analysis of the morphological, structural, biochemical, and mechanical changes of the Extracellular Matrix (ECM), which occur during meniscus development, represents the goal of the present study. Medial fully developed menisci (FD, 9-month-old pigs), partially developed menisci (PD, 1-month-old piglets), and not developed menisci (ND, from stillbirths) were collected. Cellularity and glycosaminoglycans (GAGs) deposition were evaluated by ELISA, while Collagen 1 and aggrecan were investigated by immunohistochemistry and Western blot analyses in order to be compared to the biomechanical properties of traction and compression tensile forces, respectively. Cellularity decreased from ND to FD and GAGs showed the opposite trend (p < 0.01 both). Collagen 1 decreased from ND to FD, as well as the ability to resist to tensile traction forces (p < 0.01), while aggrecan showed the opposite trend, in accordance with the biomechanics: compression test showed that FD meniscus greatly resists to deformation (p < 0.01). This study demonstrated that in swine meniscus, clear morphological and biomechanical changes follow the meniscal maturation and specialization during growth, starting with an immature pattern (ND) to the mature organized meniscus of the FD, and they could be useful to understand the behavior of this structure in the light of its tissue bioengineering.

Integrins, cadherins and channels in cartilage mechanotransduction: perspectives for future regeneration strategies

Articular cartilage consists of hyaline cartilage, is a major constituent of the human musculoskeletal system and has critical functions in frictionless joint movement and articular homoeostasis. Osteoarthritis (OA) is an inflammatory disease of articular cartilage, which promotes joint degeneration. Although it affects millions of people, there are no satisfying therapies that address this disease at the molecular level. Therefore, tissue regeneration approaches aim at modifying chondrocyte biology to mitigate the consequences of OA. This requires appropriate biochemical and biophysical stimulation of cells. Regarding the latter, mechanotransduction of chondrocytes and their precursor cells has become increasingly important over the last few decades. Mechanotransduction is the transformation of external biophysical stimuli into intracellular biochemical signals, involving sensor molecules at the cell surface and intracellular signalling molecules, so-called mechano-sensors and -transducers. These signalling events determine cell behaviour. Mechanotransducing ion channels and gap junctions additionally govern chondrocyte physiology. It is of great scientific and medical interest to induce a specific cell behaviour by controlling these mechanotransduction pathways and to translate this knowledge into regenerative clinical therapies. This review therefore focuses on the mechanotransduction properties of integrins, cadherins and ion channels in cartilaginous tissues to provide perspectives for cartilage regeneration.