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Meniscal repair is widely used as a treatment for meniscus injury. However, where meniscal damage has progressed such that repair is not possible, approaches for partial meniscus replacement are now being developed which have the potential to restore the functional role of the meniscus, in stabilising the knee joint, absorbing and distributing stress during loading, and prevent early degenerative joint disease. One attractive potential solution to the current lack of meniscal replacements is the use of decellularised natural biological scaffolds, derived from xenogeneic tissues, which are produced by treating the native tissue to remove the immunogenic cells. The current study investigated the effect of decellularisation on the biomechanical tensile and compressive (indentation and unconfined) properties of the porcine medial meniscus through an experimental–computational approach. The results showed that decellularised medial porcine meniscus maintained the tensile biomechanical properties of the native meniscus, but had lower tensile initial elastic modulus. In compression, decellularised medial porcine meniscus generally showed lower elastic modulus and higher permeability compared to that of the native meniscus. These changes in the biomechanical properties, which ranged from less than 1% to 40%, may be due to the reduction of glycosaminoglycans (GAG) content during the decellularisation process. The predicted biomechanical properties for the decellularised medial porcine meniscus were within the reported range for the human meniscus, making it an appropriate biological scaffold for consideration as a partial meniscus replacement.

Objective In order to reduce the “killer turn” effect, various tibial tunnels have been developed. However, few studies investigated the biomechanical effects of different tibial tunnels during PCL reconstruction. This study aims to compare the time‐zero biomechanical properties of anteromedial, anterolateral, lower anteromedial, and lower anterolateral tibial tunnels in transtibial posterior cruciate ligament (PCL) reconstruction under load‐to‐failure loading. Methods Porcine tibias and bovine extensor tendons were used to simulate in vitro transtibial PCL reconstruction. Forty bovine extensor tendons and 40 porcine tibias were randomly divided into four experimental groups: anteromedial tunnel group (AM group, n = 10), anterolateral tunnel group (AL group, n = 10), lower anteromedial tunnel group (L‐AM group, n = 10), and lower anterolateral tunnel group (L‐AL group, n = 10). The biomechanical test was then carried out in each group using the load‐to‐failure test. The ultimate load (in newtons), yield load (in newtons), tensile stiffness (in newtons per millimeter), load‐elongation curve, failure mode, and tibial tunnel length (in millimeter) were recorded for each specimen. One‐way analysis of variance (ANOVA) was used to compare the mean differences among the four groups. Results The biomechanical outcomes showed that there were no differences in the mean tensile stiffness and failure mode among four groups. The ultimate load and yield load of the L‐AM group were significantly higher than those of other three groups (P < 0.05). For the AM group, its ultimate load is significantly higher than that of the L‐AL group (P < 0.05), and its yield load is higher than that of the AL group and L‐AL group (P < 0.05). However, we found no significant differences in either ultimate load or yield load between AL group and L‐AL group (P > 0.05). There was significant statistical difference in the length of tibial tunnel between anatomic groups (AM and AL) and lower groups (L‐AM and L‐AL) (P < 0.05). Conclusion Compared with the anteromedial, anterolateral, and lower anterolateral tibial tunnel, the lower anteromedial tibial tunnel showed better time‐zero biomechanical properties including ultimate load and yield load in transtibial PCL reconstruction. Schematic of different tibial tunnel placement. Yellow tunnel: AM tibial tunnel; red tunnel: L‐AM tibial tunnel; green tunnel: AL tibial tunnel; black tunnel: L‐AL tibial tunnel.

Surgical resection of chest wall tumours may lead to a loss of ribcage stability and requires reconstruction to allow for physical thorax functioning. When titanium implants are used especially for larger, lateral defects, they tend to break. Implant failures are mainly due to specific mechanical requirements for chest-wall reconstruction which must mimic the physiological properties and which are not yet met by available implants. In order to develop new implants, the mechanical characteristics of ribs, joints and cartilages are investigated. Rib loading is highly dependent on the global thorax kinematics, making implant development substantially challenging. Costal cartilage contributes vastly to the entire thorax load-deformation behaviour, and also to rib loading patterns. Computational models of the thoracic cage require mechanical properties on the global stiffness, to simulate rib kinematics and evaluate stresses in the ribs and costal cartilage. In this study the mechanical stiffness of human costal cartilage is assessed with bending, torsion and tensile tests. The elastic moduli for the bending in four major directions ranged from 2.2 to 60.8 MPa, shear moduli ranged from 5.7 to 24.7 MPa for torsion, and tensile elastic moduli ranging from 5.6 to 29.6 MPa. This article provides mechanical properties for costal cartilage. The results of these measurements are used for the development of a whole thorax finite element model to investigate ribcage biomechanics and subsequently to design improved rib implants.

Tendon aging is associated with an increasing prevalence of tendon injuries and/or chronic tendon diseases, such as tendinopathy, which affects approximately 25% of the adult population. Aged tendons are often characterized by a reduction in the number and functionality of tendon stem/progenitor cells (TSPCs), fragmented or disorganized collagen bundles, and an increased deposition of glycosaminoglycans (GAGs), leading to pain, inflammation, and impaired mobility. Although the exact pathology is unknown, overuse and microtrauma from aging are thought to be major causative factors. Due to the hypovascular and hypocellular nature of the tendon microenvironment, healing of aged tendons and related injuries is difficult using current pain/inflammation and surgical management techniques. Therefore, there is a need for novel therapies, specifically cellular therapy such as cell rejuvenation, due to the decreased regenerative capacity during aging. To augment the therapeutic strategies for treating tendon-aging-associated diseases and injuries, a comprehensive understanding of tendon aging pathology is needed. This review summarizes age-related tendon changes, including cell behaviors, extracellular matrix (ECM) composition, biomechanical properties and healing capacity. Additionally, the impact of conventional treatments (diet, exercise, and surgery) is discussed, and recent advanced strategies (cell rejuvenation) are highlighted to address aged tendon healing. This review underscores the molecular and cellular linkages between aged tendon biomechanical properties and the healing response, and provides an overview of current and novel strategies for treating aged tendons. Understanding the underlying rationale for future basic and translational studies of tendon aging is crucial to the development of advanced therapeutics for tendon regeneration.

Corneal biomechanics are critical to both normal physiology and pathological conditions such as keratoconus (KC), yet existing measurement techniques fail to assess regional variations in material stiffness, limiting early diagnosis and therapeutic evaluation. This study focuses on evaluating the symmetry characteristics of bilateral corneal biomechanical properties based on a corneal inflation testing, while systematically analyzing the spatial distribution differences of biomechanical parameters in KC lesion regions and following corneal cross-linking (CXL) treatment. Thirty-six New Zealand white rabbits were divided into normal, KC-induced (via type I collagenase), and CXL-treated (riboflavin/ultraviolet light) groups. Four weeks post-intervention, corneal inflation tests were conducted, and the shear modulus (μ), the strain hardening index (α), and the tangent modulus (Et) in 25 different cornea regions were calculated. In the normal group, corneal material stiffness was similar in all 25 regions considered, with mirror symmetry and the highest Et in the upper temporal central region while the lowest in the lower temporal and peripheral nasal regions. Et of the central region reduced significantly in the KC group, while no statistical difference was found between the bilateral eyes in other 24 regions (all P > 0.05). Et enhanced after CXL, with the greatest increase in the central region and varying effects in other areas, correlating with preoperative properties. The analysis method provided a robust tool for capturing the regional biomechanical variations and derives morphology-independent biomechanical parameters, revealing localized stiffness losses in keratoconus and heterogeneous post-corneal cross linking stiffness enhancement.

Purpose Corneal biomechanics is an emerging field and the interest into physical and biological interrelations in the anterior part of the eye has significantly increased during the past years. There are many factors that determine corneal biomechanics such as hormonal fluctuations, hydration and environmental factors. Other factors that can affect the corneas are the age, the intraocular pressure and the central corneal thickness. The purpose of this review is to evaluate the factors affecting corneal biomechanics and the recent advancements in non-destructive, in vivo measurement techniques for early detection and improved management of corneal diseases. Methods Until recently, corneal biomechanics could not be directly assessed in humans and were instead inferred from geometrical cornea analysis and ex vivo biomechanical testing. The current research has made strides in studying and creating non-destructive and contactless techniques to measure the biomechanical properties of the cornea in vivo. Results Research has indicated that altered corneal biomechanics contribute to diseases such as keratoconus and glaucoma. The identification of pathological corneas through the new measurement techniques is imperative for preventing postoperative complications. Conclusions Identification of pathological corneas is crucial for the prevention of postoperative complications. Therefore, a better understanding of corneal biomechanics will lead to earlier diagnosis of ectatic disorders, improve current refractive surgeries and allow for a better postoperative treatment.

Bone disorders are of significant concern due to increase in the median age of our population. Traditionally, bone grafts have been used to restore damaged bone. Synthetic biomaterials are now being used as bone graft substitutes. These biomaterials were initially selected for structural restoration based on their biomechanical properties. Later scaffolds were engineered to be bioactive or bioresorbable to enhance tissue growth. Now scaffolds are designed to induce bone formation and vascularization. These scaffolds are often porous, made of biodegradable materials that harbor different growth factors, drugs, genes, or stem cells. In this review, we highlight recent advances in bone scaffolds and discuss aspects that still need to be improved.

[Display omitted] Decellularized extracellular matrix (d-ECM) serves as an ideal scaffold for constructing artificial ovaries, a promising approach to fertility preservation for patients experiencing premature ovarian failure. The biomechanical properties of d-ECM are crucial for the development and maturation of follicles. However, there is no standardized or comprehensive framework for evaluating the various decellularization methods proposed in the literature. In this study, we developed a novel decellularization protocol for porcine ovaries using liquid nitrogen and hypertonic saline methods, comparing its effectiveness against conventional chemical and enzymatic techniques through histological analysis, quantitative assessments and biomechanical testing. Histological analyses demonstrated that our d-ECM protocols effectively removed cellular and nuclear materials (at least 95% reduction) while preserving the structural integrity of elastin and collagen fibers (maximum 15% reduction). Furthermore, tensile testing results indicated that the novel decellularization methods using liquid nitrogen and hypertonic saline retained mechanical properties most similar to those of the fresh group. Our findings expand the evaluation of decellularization techniques by incorporating the biomechanical properties of d-ECM. Additionally, we provide valuable insights for enhancing decellularization methods and identifying optimal scaffolds for artificial ovaries.

To compare the corneal biomechanical parameters measured by Corvis ST in subjects with varying degrees of myopia. And the factors that may affect corneal biomechanical properties were also investigated. Participants in this prospective cross-sectional study were classified into three groups according to spherical equivalent (SE) and axial length (AL): Non-myopia (NM, SE > − 0.50 D and AL < 26 mm), Mild-to-moderate myopia (MM, − 6.00 D < SE ≤ − 0.50 D and AL < 26 mm), high myopia (HM, SE ≤ − 6.00 D or AL ≥ 26 mm). Ten corneal biomechanical parameters were finally included. Linear mixed-effects model accounting for using both eyes in the same participant was carried out to evaluate how the corneal biomechanical parameter was influenced by varying degrees of myopia after adjusting for biomechanically corrected intraocular pressure (bIOP) and central corneal thickness (CCT). Further, multiple linear regression was performed to explore the correlation between corneal biomechanical parameter and SE, AL, bIOP or CCT. A total of 304 eyes from 224 healthy myopic subjects were recorded. There were 95 eyes with NM, 122 eyes with MM, and 87 eyes with HM. After adjusting for bIOP and CCT, eyes with high myopia showed shorter highest concavity time (HC-time, p  = 0.025), greater peak distance (PD, p  = 0.001), greater deflection amplitude (DA-Max, p  = 0.002), smaller whole eye movement (WEM-Max, p  < 0.001) and reduced stiffness parameter (SP-A1, p  < 0.001). Multiple regression analysis showed that five parameters (HC-time, p  < 0.001; PD, p  < 0.001; DA-Max, p  = 0.001; WEM-Max, p  < 0.001; and SP-A1, p  < 0.001) of Corvis ST were significantly correlated with AL, and one parameter (Corvis biomechanical index, p  = 0.016) has significant relationship with SE. With the increase of myopia, significant changes in several corneal biomechanical parameters indicated a progressive decrease in corneal stiffness, independent of bIOP and CCT. Corneal biomechanical parameters may be predictors of scleral mechanical strength in high myopia, which has certain application value in clinical management of myopia.

Recent studies on sheep brains have demonstrated the potential of biomechanical analysis in estimating time since death. This study extends the research to human tissue to assess practical forensic applicability. Brain samples from six regions of 47 cadavers were analyzed for storage (G’), loss (G’’), and complex shear moduli (G*), and these properties were correlated with post-mortem interval (PMI), age at death, sex, edema, autolysis, blood congestion, and white-to-gray matter ratio. Significant regional differences were found: the anterior deep brain had significantly lower G’ (1621 ± 599 Pa) than the frontal white matter, medulla oblongata, and cerebellum (p ≤ 0.04). G’’ and G* also varied by region, with the lowest values in the anterior deep brain (p ≤ 0.03). Biomechanical properties were influenced by age, PMI, edema, blood congestion, and tissue composition, but not by sex or autolysis. ROC analyses yielded cut-off values in the frontal gray and posterior deep brain that accurately distinguished PMIs of ≥ 150 and ≥ 250 h, with likelihood ratios ≥ 6 and specificities ≥ 89 %. Comparative analysis with ovine tissue stored at 4 °C for four days showed biomechanical similarity to human tissue stored for an average of eight days, except for G’’ in the anterior deep brain (p < 0.01). In conclusion, human brain biomechanics offer valuable indicators for PMI estimation, with measurable properties influenced by anatomical region and biological factors. Fresh ovine brain tissue serves as a suitable surrogate for human samples stored up to eight days post-mortem. •Rheological properties measured in 6 brain regions from 47 human cadavers.•Gray and white matter showed distinct biomechanical differences.•Edema and congestion altered brain biomechanics region-specifically.•PMI and age reduced stiffness; sex and autolysis had no effect.•PMIs of 6 and 10 days at 4°C can be confirmed with high diagnostic accuracy.