Page 372 - IJB-9-3

International Journal of Bioprinting 3D-printed anistropic meniscus

Table 1. Heterogeneity of the meniscus
Aspects Contents Relevant manifestation Reference
Anatomy Shape Length: 40.5 – 45.5 mm (medial meniscus), 32.4 – 35.7 mm (lateral meniscus) [30,31]
heterogeneity Width: 27 mm (medial meniscus), 26.6 – 29.3 mm (lateral meniscus)
Shape: C-shaped (medial meniscus), O-shaped (lateral meniscus)
Vessel, nerve and lymph Red-red zone: the outer 10 – 25% of the meniscus which is penetrated with [13,21]
vessels, nerves and lymph
Red-white zone: the transitioning area [2,3]
White-white zone: the inner 1/3 of the meniscus which is avascular, aneural and
alymphatic
Biological Extracellular matrix In general: Water (72%), collagens (22%), proteoglycans (1%), DNA (2%), elastin [24,41-44]
heterogeneity components (<1%) and adhesion glycoproteins (<1%). Proportion varies with age, lesions and
pathological states.
Collagen Red-red zone: Collagen I (80% of dry weight), Collagen II, III, IV, VI, XVIII [50–52]
(<1% of dry weight)
White-white Zone: Collagen I (40% of dry weight), Collagen II (60% of dry
weight)
Collagens are hierarchically aligned, with randomly at superficial layer, [23,53]
circumferentially in deeper layer with radial fibers interwoven in the meniscus.
Cell phenotype Fusiform fibroblast-like cells in the outer zone while oval chondrocyte-like cells [47,48]
in the inner zone with respective biological actions.
Fibrochondrocytes in the peripheral region better adapt to circumferential [49]
tension while those in the inner region better withstand compressive force.
Biomechanical Compression At low strain: Circumferential: 10 MPa [27]
Heterogeneity Radial: 13 MPa
Axial: 19 MPa
At high strain: Circumferential: 288 MPa
Radial: 287 MPa
Axial: 299 MPa
(Axial stiffness is significantly greater than both circumferential and radial stiffness)
Inner zone bears compression while outer zone withstands tension. [62,63]
Tension Circumferential Medial anterior: 99.4 MPa [42,66]
Medial center: 107.9 MPa
Medial posterior: 114.1 MPa
Lateral anterior: 99.8 MPa
Lateral center: 78.4 MPa
Lateral posterior: 116.2 MPa
Radial Medial anterior: 10.5 MPa
Medial center: 7.6 MPa
Medial posterior: 2.5 MPa
Lateral anterior: 10.9 MPa
Lateral center: 10.3 MPa
Lateral posterior: 8.5 MPa
Circumferential tensile modulus is 10-fold higher than radial modulus.
Radial Young’s modulus is remarkably higher in the anterior region than [65]
posterior region.
The highest tensile strength in medial meniscus appears in the posterior region. [65]
−14
−15
Hydromechanics Hydraulic permeability ranges from 10 to 10 m /N s for confined [68]
4
−15
4
−17
compression and 10 – 10 m /N s for indentation.
Heterogeneity is also found circumferentially and radially between pars [69]
intermedia and posterior horn in fluid phase.
Volume 9 Issue 3 (2023) 364 https://doi.org/10.18063/ijb.693