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Injury and repair of ligaments and tendons

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Abstract

In this chapter, biomechanical methods used to analyze healing and repair of ligaments and tendons are initially described such that the tensile properties of these soft tissues as well as their contribution to joint motion can be determined. The focus then turns to the important mechanical and biological factors that improve the healing process of ligaments. The biomechanics of surgical reconstruction of the anterior cruciate ligament and the key surgical parameters that affect the performance of the replacement grafts are subsequently reviewed. Finally, injury mechanisms and the biomechanical analysis of various treatment techniques for various types of tendon injuries are described.
... Tendon tissues have specialized mechanical properties and have features of linear elastic material models as well as viscoelastic material models. In fact, mathematical methods termed quasilinear viscoelasticity models have been used to model tendon tissue's mechanical behavior (Woo et al., 2000). ...
... Viscoelastic materials demonstrate different mechanical properties depending on the rate of loading (Woo et al., 2000;. One characteristic of viscoelastic materials such as tendons is creep, the deformation of a material in response to constant load (Jaiswal et al., 2020). ...
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Research has shown that the surrounding biomechanical environment plays a significant role in the development, differentiation, repair, and degradation of tendon, but the interactions between tendon cells and the forces they experience are complex. In vitro mechanical stimulation models attempt to understand the effects of mechanical load on tendon and connective tissue progenitor cells. This article reviews multiple mechanical stimulation models used to study tendon mechanobiology and provides an overview of the current progress in modelling the complex native biomechanical environment of tendon. Though great strides have been made in advancing the understanding of the role of mechanical stimulation in tendon development, damage, and repair, there exists no ideal in vitro model. Further comparative studies and careful consideration of loading parameters, cell populations, and biochemical additives may further offer new insight into an ideal model for the support of tendon regeneration studies.
... Achilles tendon ruptures are reported among one of the highest sports-related injuries (Soldatis, Goodfellow, & Wilber, 1997). Depending on the type of injury and the location of the tendon, the clinical repair involves a variety of different suture techniques (Woo et al., 2000). Typically if the tendon reruptures it is at the knots in the suture and is a weak point of tendon repair (Woo et al., 2000). ...
... Depending on the type of injury and the location of the tendon, the clinical repair involves a variety of different suture techniques (Woo et al., 2000). Typically if the tendon reruptures it is at the knots in the suture and is a weak point of tendon repair (Woo et al., 2000). ...
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At the most basic level, tendons connect muscle to bone, and ligaments connect bone to bone. Tendons and ligaments (T/L) have transition areas at the boundaries that are highly specialized. The enthesis, where the tissue attaches to the bone, is categorized into four zones. The structure of the four zones, (1) tendon, (2) fibrocartilage, (3) mineralized fibrocartilage, and (4) bone, gradually change in cellular and molecular composition to avoid rupture by dispersing areas of high tension in the area between tendon and bone. Tendons and muscles connect at the myotendinous junction. Tendon fibers are set deep within the muscle between muscle cells and when a force is created by muscle contraction in the intracellular contractile muscle proteins, the force is then transmitted to the collagen fibrils of the tendon, which allow for tendon movement.
... Their composition consists of fibroblasts embedded in a specialised extracellular matrix (ECM), comprised mainly of type I collagen, and elastin with a range of non-collagenous proteins and proteoglycans [2]. The knee joint anterior cruciate ligament (ACL) is one of the most frequently injured ligaments [3] resulting in significant joint instability, immobility [3], muscle atrophy [4] and induction of knee joint osteoarthritis (OA) [5]. Knee joint OA has major physical, social and financial implication for the ageing population [6]. ...
... Their composition consists of fibroblasts embedded in a specialised extracellular matrix (ECM), comprised mainly of type I collagen, and elastin with a range of non-collagenous proteins and proteoglycans [2]. The knee joint anterior cruciate ligament (ACL) is one of the most frequently injured ligaments [3] resulting in significant joint instability, immobility [3], muscle atrophy [4] and induction of knee joint osteoarthritis (OA) [5]. Knee joint OA has major physical, social and financial implication for the ageing population [6]. ...
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Aim Cruciate ligaments (CLs) of the knee joint are commonly injured following trauma or ageing. MicroRNAs (miRs) are potential therapeutic targets in musculoskeletal disorders. This study aimed to 1) identify if wild-stock house (WSH) mice are an appropriate model to study age-related changes of the knee joint and 2) investigate expression of miRs in ageing murine CLs. Methods Knee joints were collected from 6 and 24 months old C57BL/6 and WSH mice ( Mus musculus domesticus ) for histological analysis. RNA extraction and qPCR gene expression were performed on CLs in 6, 12, 24, and 30 month WSH old mice. Expression of miR targets in CLs was determined, followed by analysis of predicted mRNA target genes and Ingenuity Pathway Analysis. Results Higher CL and knee OARSI histological scores were found in 24 month old WSH mice compared to 6 and 12 month old C57BL/6 and 6 month old WSH mice ( p < 0.05). miR-29a and miR-34a were upregulated in 30 month-old WSH mice in comparison to 6, 12 and 24-month-old WSH mice ( p <0.05). Ingenuity Pathway Analysis on miR-29a and 34a targets was associated with inflammation through interleukins, TGFβ and Notch genes and p53 signalling. Collagen type I alpha 1 chain (COL1A1) correlated negatively with both miR-29a (r= -0.35) and miR-34a (r= -0.33). Conclusion The findings of this study support WSH house mice as an accelerated ageing model of the murine knee joint. This study also indicated that miR-29a and 34a may be important regulators of COL1A1 gene expression in murine CLs.
... Decreased loading of the ligament also affects the structure of the ligament-bone junction (enthesis) causing the subperiosteal osteoclasts to resorb much of the ligamentous insertions on the bone [68]. Further, with immobilization the cross-sectional area of the ACL is reduced, hypothesized to be due to a loss in collagen fibrils, glycosaminoglycans (GAGs), and altered remaining collagen fibril orientation [69]. In contrast, joint motion (active or passive range of motion [ROM]) and/or loading leads to more connective tissue (with a smaller percentage of crosslink pattern of collagen), increased localized blood flow, and increased ultimate strength of the ligament. ...
... In contrast, joint motion (active or passive range of motion [ROM]) and/or loading leads to more connective tissue (with a smaller percentage of crosslink pattern of collagen), increased localized blood flow, and increased ultimate strength of the ligament. Different ligaments may heal at different rates, and when a combination of ligaments are injured, they heal with inferior ligamentous quality and more slowly than with isolated injuries [69][70][71][72][73][74][75][76]. Following ligamentous surgical reconstruction, the reconstructed graft strength will eventually exhibit similar ultimate strength, but will vary depending on graft type, donor age, and donor characteristics (autograft vs allograft, patellar tendon vs hamstring graft) [77,78]. ...
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Mechanical loading to the knee joint results in a differential response based on the local capacity of the tissues (ligament, tendon, meniscus, cartilage, and bone) and how those tissues subsequently adapt to that load at the molecular and cellular level. Participation in cutting, pivoting, and jumping sports predisposes the knee to the risk of injury. In this narrative review, we describe different mechanisms of loading that can result in excessive loads to the knee, leading to ligamentous, muscu-lotendinous, meniscal, and chondral injuries or maladaptations. Following injury (or surgery) to structures around the knee, the primary goal of rehabilitation is to maximize the patient's response to exercise at the current level of function, while minimizing the risk of re-injury to the healing tissue. Clinicians should have a clear understanding of the specific injured tissue(s), and rehabilitation should be driven by knowledge of tissue-healing constraints, knee complex and lower extremity biomechanics, neuromuscular physiology, task-specific activities involving weight-bearing and non-weight-bearing conditions , and training principles. We provide a practical application for prescribing loading progressions of exercises, functional activities, and mobility tasks based on their mechanical load profile to knee-specific structures during the rehabilitation process. Various loading interventions can be used by clinicians to produce physical stress to address body function, physical impairments, activity limitations, and participation restrictions. By modifying the mechanical load elements, clinicians can alter the tissue adaptations, facilitate motor learning, and resolve corresponding physical impairments. Providing different loads that create variable tensile, compressive, and shear deformation on the tissue through mechanotransduction and speci-ficity can promote the appropriate stress adaptations to increase tissue capacity and injury tolerance. Tools for monitoring rehabilitation training loads to the knee are proposed to assess the reactivity of the knee joint to mechanical loading to monitor excessive mechanical loads and facilitate optimal rehabilitation. Key Points Mechanical loads encountered during high-risk cutting, pivoting, and jumping sports predispose the structures of the knee to risk of injury. Individual tissues of the knee respond and adapt differently to various mechanical load stimuli. Appropriate selection of exercises, functional activities , and mobility tasks based on their mechanical load profile can be utilized during rehabilitation to systematically and progressively load the structure of the knee to promote tissue healing and repair.
... ACL injury has a high incidence in the population, and ACL fractures caused by noncontact mechanisms are common [2]. During exercise, sudden torsion, sudden stop, and weight-bearing can lead to ACL overload, resulting in ACL tear or even fracture [3]. Ligament injury can not only cause joint pain, cartilage and meniscus damage, and other soft tissue damage in the joint but may also even induce osteoarthritis if not treated in time [4]. ...
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This study aimed to analyze the influence of artificial intelligence (AI) reconstruction algorithm on computed tomography (CT) images and the application of CT image analysis in the recovery of knee anterior cruciate ligament (ACL) sports injuries. A total of 90 patients with knee trauma were selected for enhanced CT scanning and randomly divided into three groups. Group A used the filtered back projection (FBP) reconstruction algorithm, and the tube voltage was set to 120 kV during CT scanning. Group B used the iDose4 reconstruction algorithm, and the tube voltage was set to 120 kV during CT scanning. In group C, the iDose4 reconstruction algorithm was used, and the tube voltage was set to 100 kV during CT scanning. The noise, signal-to-noise ratio (SNR), carrier-to-noise ratio (CNR), CT dose index volume (CTDI), dose length product (DLP), and effective radiation dose (ED) of the three groups of CT images were compared. The results showed that the noise of groups B and C was smaller than that of group A ( P < 0.05), and the SNR and CNR of groups B and C were higher than those of group A. The images of patients in group A with the FBP reconstruction algorithm were noisy, and the boundaries were not clear. The noise of the images obtained by the iDose4 reconstruction algorithm in groups B and C was improved, and the image resolution was also higher. The agreement between arthroscopy and CT scan results was 96%. Therefore, the iterative reconstruction algorithm of iDose4 can improve the image quality. It was of important value in the diagnosis of knee ACL sports injury.
... Fatigue micro-damage in the inter-fascicle space was observed in the first hour of the 3% strain group (Fig. 4). The level of additional microdamage observed, particularly by the end of the second hour in the 6% group, is consistent with previous reports (Hamilton et al., 2008;Järvinen et al., 1997;Maffulli and Kader, 2002;Waterston et al., 1997;Woo et al., 2000) and is a marker of tertiary structure loss (Sivaguru et al., 2014), which is reflected in the concurrent loss of mechanical integrity. ...
Article
The response of white New Zealand rabbit Achilles tendons to load was assessed using mechanical measures and confocal arthroscopy (CA). The progression of fatigue-loading-induced damage of the macro- (tenocyte morphology, fiber anisotropy and waviness), as well as the mechanical profile, were assessed within the same non-viable intact tendon in response to prolonged cyclic and static loading (up to four hours) at different strain levels (3%, 6% and 9%). Strain-mediated repeated loading induced a significant decline in mechanical function (p < 0.05) with increased strain and cycles. Mechanical and structural resilience was lost with repeated loading (p < 0.05) at macroscales. The lengthening of D-periodicity correlated strongly with the overall tendon mechanical changes and loss of spindle shape in tenocytes. This is the first study to provide a clear concurrent assessment of form (morphology) and function (mechanics) of tendons undergoing different strain-mediated repeated loading at multiple-scale assessments. This study identifies a variety of multiscale properties that may contribute to the understanding of mechanisms of tendon pathology.
... However, the effects of alignment on the observed axon strain seem to be diminished in heterogeneous networks (sparse center and dense center networks, Fig. 6, 7). This result could imply that a loss of alignment during ligament healing (Woo et al. 2000) or increases in alignment in collagen gels (Allen and Schor 1983; Barocas and Tranquillo 1997b; Zhang et al. 2014) may have less effect on axon strain than the presence of collagen network heterogeneity. These results further emphasize the importance of measuring collagen network heterogeneity and defining such relationships to axon strain. ...
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In innervated collagenous tissues, tissue scale loading may contribute to joint pain by transmitting force through collagen fibers to the embedded mechanosensitive axons. However, the highly heterogeneous collagen structures of native tissues make understanding this relationship challenging. Recently, collagen gels with embedded axons were stretched and the resulting axon signals were measured, but these experiments were unable to measure the local axon strain fields. Computational discrete fiber network models can directly determine axon strain fields due to tissue scale loading. Therefore, this study used a discrete fiber network model to identify how heterogeneous collagen networks (networks with multiple collagen fiber densities) change axon strain due to tissue scale loading. In this model, a composite cylinder (axon) was embedded in a Delaunay network (collagen). Homogeneous networks with a single collagen volume fraction and two types of heterogeneous networks with either a sparse center or dense center were created. Measurements of fiber forces show higher magnitude forces in sparse regions of heterogeneous networks and uniform force distributions in homogeneous networks. The average axon strain in the sparse center networks decreases when compared to homogeneous networks with similar collagen volume fractions. In dense center networks, the average axon strain increases compared to homogeneous networks. The top 1% of axon strains are unaffected by network heterogeneity. Based on these results, the interaction of tissue scale loading, collagen network heterogeneity, and axon strains in native musculoskeletal tissues should be considered when investigating the source of joint pain.
... Musculoskeletal tissue injuries such as tendon and ligament pathologies are common in the elderly and especially in athletes, with traumatic rupture of the anterior cruciate ligament and Achilles tendinopathy being the most common [369]. Scharf et al. established an IONP-based cell tracking method in a sheep model of tendinitis [370]. ...
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Chapter
According to contemporary knowledge of tissue regeneration there are three basic components: cells, porous 3d scaffolds, growth stimulating material or signals. The need for tissue engineering was conceived for the purpose of repairing or replac ing part or all of the damaged, injured or missing tissues or organs due to trauma, disease or injury. Stem cells are self‐renewing cells. Tissue engineered scaffolds are used as a device upon which cells are seeded and cultured in vitro. Fabrication of functional scaffolds is addressed at two levels: micro scale, which is suitable for cell survival and function, and macro‐scale for coordination of nutrient transport, multicellular process, mechanical properties. Ceramic nanoparticles are inorganic compounds made up of oxides, car bides, phosphates, and carbonates of metals and metalloids such as calcium, titanium, silicon. The future perspectives for this innovative nanomaterial‐based research area demand many conceptual improvements in cytoskeletal, neuronal, and cardiovascular therapies along with angiogenesis.
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This study was designed to determine the effects of in vivo multistrand, multigrasp suture techniques on the strength and gliding of repaired intrasynovial tendons when controlled passive motion rehabilitation was used. Twenty-four adult mongrel dogs were divided into 4 groups and their medial and lateral forepaw flexor tendons were transsected and sutured by either the Savage, the Tajima, the Kessler, or the recently developed 8-strand suture method. The tendon excursion, joint rotation, and tensile properties of the repaired tendons were evaluated biomechanically at 3 and 6 weeks after surgery. It was found that neither time nor suture method significantly effected proximal and distal interphalangeal joint rotation or tendon excursion when the 4 techniques were compared to each other. Normalized load value (experimental/control) was significantly affected by both the suture method and the amount of time after surgery, however. The Savage and 8-strand repair methods had significantly greater strength than did the Tajima method at each time interval (p < .05 for each comparison). In addition, the 8-strand method had significantly greater normalized load values than did the Savage method at each time interval (p < .05 for each comparison). Normalized stiffness (experimental/control) for the 8-strand repair method was significantly greater than that for the Tajima and Savage methods at 3 and 6 weeks after surgery (p < .05). In addition, the normalized stiffness values for the 6-week groups was significantly greater than those for the 3-week groups (p < .05). It was concluded that the method of tendon suture was a significant variable insofar as the regaining of tendon strength was concerned and that the newer low-profile 8-strand repair method significantly expands the safety zone for the application of increased in vivo load during the early stages of rehabilitation.
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