Ligament structure, physiology and function

McCaig Centre for Joint Injury and Arthritis Research, University of Calgary, Calgary, Alberta, Canada.
Journal of musculoskeletal & neuronal interactions (Impact Factor: 1.74). 07/2004; 4(2):199-201.
Source: PubMed


Ligaments are specialized connective tissues with very interesting biomechanical properties. They have the ability to adapt to the complex functions that each are required to perform. While ligaments were once thought to be inert, they are in fact responsive to many local and systemic factors that influence their function within the organism. Injury to a ligament results in a drastic change in its structure and physiology and creates a situation where ligament function is restored by the formation of scar tissue that is biologically and biomechanically inferior to the tissue it replaces. This article will briefly review the basic structure, physiology and function of normal versus healing knee ligaments, referring specifically to what is known about two of the most extensively studied and clinically relevant knee ligaments, the anterior cruciate (ACL) and medial collateral (MCL) ligaments of the knee. Those readers wishing for more comprehensive sources of information on ligament biology and biomechanics are referred to many excellent reviews on these topics.

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    • "Skeletal ligaments are defined as dense bands of collagenous tissue (fibers) that span a joint and then become anchored to the bone at either end. They vary in size, shape, orientation, and location.[1] "
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    ABSTRACT: Trietz ligament connects the duodeno-jejunal flexure to the right crus of the diaphragm. There are various opinions regarding the existence of the smooth muscle fibers in the ligament. We want to resolve this complexity with microscopic study of this part in cadavers. This study done on three cadavers in the medical faculty of Isfahan University of Medical Sciences. Three samples of histological specimens were collected from the upper, the central, and the lower parts of Trietz ligament and were stained by H and E staining and Mallory's trichrome stain. Three samples were collected from the regions of exact connection of the main mesentery to the body wall, the intestine, and the region between these two connected regions, and these specimens were stained. In the microscopic survey, no collagen bundles were observed in the collected samples of the Trietz ligament after the dense muscular tissues. In the samples which were collected to work on collagen tissues stretching from the Trietz ligament to the main mesentery of intestine, no collagen bundles were observed. Trietz ligament is connected to the right crus of the diaphragm from the third and the fourth parts of the duodenum. Number of researchers state that there are smooth and striated muscular tissues and some others, with regard to observations of histological phases made from the samples of Trietz muscles, conclude that it can probably be noted that muscular bundles or the dense connective tissue bundles of collagen cannot be observed in the way we imagine.
    01/2014; 3:69. DOI:10.4103/2277-9175.125853
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    • "The abnormal cross-linking of collagen and the smaller diameters in collagen fibrils in repaired ligament tissue cause weakness in both tissue strength and tissue stiffness, often remaining for months or years after initial injury [46] [49] [50] [52] [56] [62] [63]. In addition, evidence suggests that remodeled collagen fibrils are not packed as densely as in normal ligaments, and the remodeled tissue appears to contain materials other than collagen, such as blood vessels, fat cells, and inflammatory cell pockets, all of which contribute to its weakness [1] [46] [49]. "
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    ABSTRACT: Ligament injuries are among the most common causes of musculoskeletal joint pain and disability encountered in primary practice today. Ligament injures create disruptions in the balance between joint mobility and joint stability, causing abnormal force transmission through the joint, which results in damage to other structures in and around the joint. The long-term consequence of nonhealed ligament injury is osteoarthritis, the most common joint disorder in the world today. Ligaments heal through a distinct sequence of cellular events that take place in three consecutive stages: an acute inflammatory phase, a proliferative or regenerative phase, and a tissue remodeling phase. The process can take months to resolve itself, and despite advances in therapeutics, many ligaments do not regain their normal tensile strength. Various diagnostic procedures have been used to determine and assess ligament injury. Traditionally, MRI and X-rays have been the most utilized techniques; however, because ligaments do not show up clearly with these devices, there have been many false positives and negatives reported due to inconclusive or inaccurate readings. Newer technologies, such as ultrasound and digital motion X-ray, are able to provide a more detailed image of a ligament's structure and function. Numerous strategies have been employed over the years attempting to improve ligament healing after injury or surgery. One of the most important of these is based on the understanding that monitoring early resumption of activity can stimulate repair and restoration of function and that prolonging rest may actually delay recovery and adversely affect the tissue's response to repair. Likewise, there is a shift away from the use of steroid injections and nonsteroidal anti-inflammatory medications. Although these compounds have been shown effective in decreasing the inflammation and pain of ligament injuries for up to six to eight weeks, their use has been shown to inhibit the histological, biochemical, and biomechanical properties of ligament healing. For this reason their use is cautioned against in athletes who have ligament injuries. Such products are no longer recommended for chronic soft tissue injuries or for acute ligament injuries, except for the shortest possible time, if at all. Regenerative medicine techniques, such as prolotherapy, have been shown, in both case series and clinical studies, to resolve ligament injuries of the spine and peripheral joints. More research and additional studies are needed to better assess ligament injuries and healing properties.
    The Open Rehabilitation Journal 01/2013; 6.
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    • "Both showed increased stiffness, but only the younger male tendons were hypertrophied, which may be an indication that tendon adaptation is affected by age. Ligaments have a similar structure to tendons, but create passive (non-contractile) connections between bones, providing stability to joints and preventing unwanted movement (Frank 2004; Whiting and Zernicke 1998). Ligaments may respond to increased mechanical loads by increasing in size, strength and stiffness (Tipton et al. 1975; Whiting and Zernicke 1998). "
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    ABSTRACT: In bioarchaeological studies, entheseal change is commonly used to infer patterns of activity in past populations. This category of skeletal modification includes both pathological changes (enthesopathies) and changes in size, shape and surface complexity (robusticity). Despite the recent impetus to reassess the use of enthesopathies as markers of activity, robusticity has received little critical attention. In this review, we reassess key assumptions that underpin the use of robusticity in activity studies, drawing on anatomical, physiological, biomechanical and sports medicine literature sources. We find that, whilst there is some evidence to support the assumption that variation in enthesis robusticity reflects different activity patterns, little is known about the process through which this variation is produced. Presently, the stimuli (dynamics of muscle use or muscle size) for entheseal adaptation are ill-defined, a situation that limits our interpretive abilities. Consideration of bone functional adaptation principles and of the relationship of entheses to soft tissue also highlights how other factors, such as age, sex and genetic background, may influence enthesis robusticity and obscure activity-related adaptation. Understanding how these factors influence enthesis robusticity helps define how robusticity studies should be controlled, but further research is required to clarify how these factors interact with activity in robusticity development and the precise relationship between activity and robusticity. Ultimately, this review emphasises the complexity of entheseal structures and their morphological development. Any interpretation of activity from enthesis robusticity should be approached with caution, but in some circumstances, the endeavour may be ill-advised.
    Journal of Archaeological Method and Theory 09/2012; 21(3):1-23. DOI:10.1007/s10816-012-9156-1 · 1.39 Impact Factor
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