Why is a ligament important

Even though, both injuries are very painful and bothersome, ligaments need more time to be completely healed. So, there are several things to take into consideration to prevent this from happening, but the first one is not to make any sudden movement that we know it will harm our body in any way.

Some examples of what you should not do is exceeding your time of exercising without the previous warm up, making moves for which you are not prepared, etc. Post Comment. Leave a Reply Cancel Reply Your email address will not be published. As mentioned often in class, many soft tissues have the same general nonlinear stress-strain curve as those we have seen for ligaments, tendons, blood vessels, and the cartilage solid matrix.

This nonlinear stress-strain relationship is illustrated schematically below:. For the stress-strain relationship above, we assume that the tissue has been cyclically loaded and that the stress-strain curve has a repeatable loading and unloading portion.

We then neglect viscoelastic influences and model the tissue as pseudo-elastic, where the loading and unloading curves are treated as separate elastic materials. We can characterize the constitutive or stress strain equations of pseudo-elastic nonlinear soft tissues using a strain energy function. A strain energy function contains a measure of tissue deformation like the Green-Lagrange strain or Right Cauchy deformation tensor, plus constants that must be determined experimentally.

The ability to quantify the constitutive equations of soft tissues this way is important for studying structure-function relationships and mechanically mediated tissue adaptation. We have already seen examples of this showing changes in experimental constants of blood vessel strain energy functions due to disease and adaptation. In this section, we present examples of strain energy functions and constitutive behaviors for other soft tissues including skin, kidney and brain tissue.

We also present a general strain energy function for soft tissues proposed by Fung. Skin is the largest organ in the body. It is composed of two layers, the epidermis and the dermis. The epidermis is the outermost layer and is between 15 and a hundred cells thick. The cell types are keratinocytes. The epidermis has no blood vessels. It relies on the dermis for nutrients. The dermis itself consists of two layers, the more superficial papillary dermis and the deeper reticular dermis.

The papillary dermis is the thinner of the two layers, and contains blood vessels, elastic fibers, collagen and reticular fibers.

The deeper reticular dermis contains larger blood vessels, interlaced elastin fibers, and parallel bundels of collagen fibers. It contains fibroblasts and mast cells.

The fibroblasts are the major cell type and produce the elastin and collagen within the papillary dermis. The dermis also contains a ground substance, containing mainly hyaluronic acid, chondroitin sulfate and glycoproteins. You will notice, however, that in comparison with other soft tissues, skin has a very long toe region. Tong and Fung characterized soft tissue mechanics using a strain energy function of the form:. As with any other strain energy function, to determine the 2nd Piola-Kirchoff stress as a function of the Green-Lagrange strain for skin, we differentiate the strain energy function with respect to the appropriate Green-Lagrange strain component.

Thus, to determine stress components for the skin we have:. Lets look at an an example of calculating S11 using the above strain energy function. We can actually calculate the derivative using symbolic manipulation in MATLAB, which is useful since the derivative, although straight-forward requires a fair amount of bookkeeping. This is done as:. Although brain tissue does not spring right to mind when thinking about tissue mechanics, the mechanical properties of brain tissue are of interest for at least two significant applications: understanding head injury and in simulating neurosurgery.

In the first case, we need to know the response of brain tissue under very high loading rates. Under these circumstances, the ability to model viscoelastic effects in brain tissue loading would be necessary. For neurosurgical simulation, the loading would be expected to be much slower, approaching in the limit a quasi-static loading. Miller and Chinzei J. We will focus on the applications of the model for very slow loading, where the brain tissue can be modeled as nonlinear elastic.

Miller and Chinzei used a platen loading device to test samples of brain tissue as shown below:. A typical stress-strain curve for brain tissue at the slowest loading rate along with the model fit from Miller and Chinzei is shown below:. For finite deformation of brain tissue, Miller and Chinzei proposed the following strain energy function:.

It is important to note, that in constrast to strain energy functions we have studied so far, this one is a function of the Left Cauchy Deformation tensor not the Right Cauchy Deformation tensor. In the case of slow speed test results that are best modeled without viscoelastic influences, Miller and Chinzei found that the experimental data could best be fit with only two constants.

Kidney is another tissue that is not thought of in terms of its mechanical properties. However, even though kidney is not a load bearing tissue, its mechanical properties are important in at least three instances: trauma, surgical simulation, and simulation for radiation treatment, where deformation of the kidney may affect the envelope to which radiation is delivered.

Farhad et al. Biomech , recently presented both experimental and theoretical models for the nonlinear mechanical behavior of pig kidneys.

Farshad et al. They found that only 5 Newtons of load was sufficient to cause significant deformation of kidney tissue. They found that 20 N of force would be sufficient to rupture the tissue. To model the nonlinear stress stain behavior of kidney, Farhad utilized a mechanical model known as the Blatz-Ko model.

This model relates stress S to the principal stretch ratios l as:. They found that the kidney tissue was anisotropic with different experimental constants for different testing directions.

Specifically, they found:. By integrating the above expression for stress, we can derive a strain energy function for the kidney tissue:. Thus, as with other soft tissues, we can derive a strain energy function to describe the constitutive behavior of kidney tissue.

For structure-function purposes, it would now be possible to relate measures of tissue structure to the experimental constants in the strain energy function.

A classification of soft tissues for which material models have only recently been developed is that of muscle tissue. There are three types of muscle tissue: 1 skeletal or striated, 2 smooth and 3 cardiac. A major challenge in modeling muscle tissue is that in addition to passive nonlinear properties, muscle tissue can generate force, termed activation force.

In addition, as we have seen in blood vessels with adaptation of the media layer, muscle tissue adapts in reponse to mechanical stimulus.

The ability of cardiac muscle to adapt to mechanical stimulus is believed to play a major role in cardiac development and normal heart function depends significantly on cardiac development Xie and Perucchio , It is believed that development of the trabeculated myocardium in the heart is modulated by stress and strain fields. To test hypotheses concerning mechanical influence on myocardium development, one must first be able to calculate stress and strain fields.

This requires development of a material model for the myocardium. In addition to having nonlinear material behavior, the myocardium has a hierarchical structure as do all biological soft tissues. An example of the trabeculated microstructure from Xie and Perucchio is shown below:. Thus, to determine the overall or effective behavior of the trabecular myocardium, Xie and Perucchio assumed a strain energy function for the myocardial microstructure, based on earlier work by Taber:.

The first term is similar to other soft tissues and represents the passive nonlinear properties of the trabeculated myocardium microstructure muscle. The second term is new and accounts for the fact that muscle fibers can generate active stress.

When modeling muscle as a nonlinear material with active stress generation potential, a common approach is write the strain energy function in two parts: 1 a part representing passive tissue properties and 2 a part representing active force generation.

This general approach can be written as:. It is imporant to note that the strain energy function above is written for the myocardial trabeculated microstructure. To determine the overall mechanics of the heart muscle, we must also have a material model for the overall effective heart mechanics. The effective heart mechanics will be a function of the microstructural material properties, as well as the architecture of the trabeculated myocardium. To determine effective behavior, we must also propose a material model for the effective level.

Xie and Perucchio proposed the following passive and active strain energy functions:. In the active strain energy function Wa , the normal strains are used as a scaling factor to represent alignment and stiffening of muscle fibers with increasing strain. To compute the experimental constants a1 - a7, Xie and Perucchio simulated the response of the trabeculated myocardium assuming the microstructural material properties being subject to a biaxial state of strain, and the third direction of strain fixed to zero:.

The corresponds to the boundary conditions illustrated below:. An additional set of boundary conditions was then used to test the fitting of the first boundary condition representing uniaxial stretch. An example of the numerical model from Xie and Perucchio is shown below:. After running the numerical simulation, computing the average 2nd Piola-Kirchoff stress and Green-Lagrange strain, an optimization procedure was used to compute the coefficients for the proposed material model. The optimization model computes the model coefficients such that the stress computed from the material model matches that from the finite element calculation:.

The results showing stress strain behavior for both passive and active tissue under biaxial deformation is shown below:. The results showing the data from the numerical simulation and the optimal fit for the uniaxial case is shown below:. In this work, the finite element calculation plays the role of the mechanical test.

This manuscript demonstrates the hierarchical nonlinear behavior of soft tissues and the use of optimization technique to compute the constants for the material model. Due to the consistent nature of soft tissue nonlinear mechanical behavior, Fung proposed a general form of a strain energy function that could be adapted to any soft tissue.

Since it is a general function, it contains many experimental constants that may be neglected depending on the tissue. This general strain energy function contains the two major features of any strain energy function we have examined so far: a measure of deformation and constants to be fit to experimental data:. This general form would a framework for consistent modeling of soft tissues and development of structure-function relationships.

Structure, Function and Adaptation of Blood Vessels. Although we don't often view them in this context, blood vessels are subject to mechanical stress during the pumping of blood. Thus, blood vessels must have mechanical properties that can withstand these stresses. Again, the mechanical properties of blood vessels are a function of the underlying tissue structure. Since blood vessels are soft collagenous tissues with a good deal of elastin , another biomolecule , their stress-strain behavior resembles that of other soft collagenous tissues like ligaments and tendons.

Thus, we can approximate their behavior under cyclic stress as pseudoelastic , nonlinear material, which implies hyperelasticity modeling. In this section, we will give a brief overview of blood vessel structure, followed by an overview of modeling blood vessels as hyperelastic materials and the relationship of blood vessel properties to their structure, and finally, a description of mechanically mediated adaptation of blood vessels.

In general the circulatory system of blood vessels may be broken down into those vessels that deliver oxygenated blood to tissues: the arteries, arterioles, and capillaries, and those vessels that return blood with carbon dioxide for gas exchange: the veins and venules.

The basic structure of all these vessels can be broken down into three layers:. The Intima 2. The Media 3. The Adventia. It is the materials that make up these layers and the size of these three layers themselves that differentiates arteries from veins and indeed even one artery from another artery or one vein from another vein.

A schematic from Fung's "Mechanical Properties of Living Tissues" shown below gives an overview of the different structures in the different types of blood vessels:.

Although a little bit difficult on the reproduced schematic, arteries have a large media layer than veins. Since smooth muscle is generally found in the media layer, this means that arteries have more smooth muscle to contract than do veins.

Arteries have a higher amount of elastin than veins. Thus, veins have a higher ratio of collagen to elastin than do arteries. In addition, veins have a thicker adventia layer in proportion to the media layer than do arteries. Innermost layer Contains endothelial cells Basal lamina 80 nm thick Subendothelia layer with collagenous bundles, some elastin.

Middle Layer Contains mainly smooth muscle cells Collagenous fibrils type III collagen Divided from adventia by elastin layer elastin is a protein which is very elastic, can undergo a stretch ratio of 1. An example of the percentage of all the components is given below in a table from Fung :.

Once we know something about tissue structure, the next natural question is: How does this structure contribute to mechanical function? If we view the mechanical behavior of blood vessels using the typical non-linear soft tissue stress strain curve, we can make qualitative statements about how tissue constituents affect mechanical behavior. Roach and Burton in digested collagen out of blood vessels using trypsin , and digested elastin from blood vessels using formic acid.

They found that collagen contributed mainly to the linear region of the nonlinear stress-strain curve while elastin contributed mainly to the toe part of the stress-strain curve. We can see this in stress strain curve from a human vena cava below:. Another critical aspect of blood vessel behavior is residual stress. This means that even in the unloaded state, there is still stress in the artery.

This state of residual stress is dependent on the thickness and the composition of the artery. In fact, as arteries are remodeled in response to mechanical stress, the amount of residual stress changes, as we will see in the section on mechanically mediated vessel adaptation.

A mark of the amount of residual stress is how much the blood vessel will open when cut. Since the blood vessel is under stress, when we cut the vessel, the stress holding the vessel together is removed and the blood vessel springs open. A figure from Fung below shows that different amounts of residual stress are present in different arteries:. If we desire a more quantitative description of blood vessel mechanics than toe versus linear region, than we can model the blood vessel as a pseudoelastic material using hyperelastic strain energy functions.

In that case, the blood vessel is often described as a cylinder, with stress and strain represented using cylindrical coordinates. We use the 2nd Piola-Kirchoff stress tensor and Green-Lagrange strain tensor to represent the stress and strain in the blood vessel, respectively.

These are denoted below:. An example of a test set-up to test blood vessels from Fung's laboratory is shown below:. The test set-up allows for torsional , tensile and pressure testing.

The blood vessel itself must be kept in a saline bath during testing. Of course, when performing these tests we need to have a constitutive model in mind to describe the tissue mechanical behavior. For a hyperelastic model, we need to use a strain energy function.

For blood vessel mechanics, there are two types of strain energy functions often used. The first form often used is the polynomial form, given below in terms of cylindrical Green-Lagrange strain components:. The second form uses an exponential function:. The above forms neglect shear stress, assuming a very thin vessel. To calculate the stress components, we differentiate the strain energy function with respect to the strain components:.

As can be expected from differences in tissue structures, there are differences in the constants for the strain energy functions for different arteries. To gain some insight into how the coefficients in the strain energy function affect the shape of the stress strain curve, we will use MATLAB to plot the stress strain curve for the Carotid and Aorta arteries modeled using a polynomial strain energy function.

The strain energy function is shown below:. To obtain the 2nd Piola-Kirchoff stress component S qq , we differentiate the strain energy function with respect to E qq we can also get Szz by differentiating W with respect to Ezz :. This illustrates a very important aspect of nonlinear stress strain relationships. The amount of strain in one direction can influence uniaxial strain in the other direction. Let us use the following constants in the above stress relation for the plot:.

Artery C KPa a1 a2 a4. Carotid 2. We we run the above code, we obtain the following plots, where the upper curve is the aorta and the lower curve is the carotid artery:. To see the senstivity of stress derived from the strain energy function to the parameters in the strain energy function, we first vary the constant C, changing from 2. We get the plot shown below:. We see that C increasing C slightly shifts the curve to become stiffer, along almost the whole graft.

If instead we increase a1 from 2. Here we see a dramatic stiffening of the material, especially in the linear zone. Although quantitative statistical results are not reported in the text, you can see that relating specific tissue attributes like the amount of collagen vs. In addition to derving strain energy functions for the whole blood vessel, Fung performed bending experiments on arteries and used composite beam theory to back out some constants for each layer.

He found significant differences in the linear portion of the stress strain curve for the intima -media layer vs. In the thoracic arteries of pigs, he found a modulus of These results indicate that the difference in structure between the layers affects the mechanical properties..

Mechanically and Disease mediated Blood Vessel Adaptation. There primary ways that blood vessel tissue structure changes in through aging, disease, and change in mechanical load. Sometimes it is a combination of all three factors. For example, hypertension or high blood pressure is a disease that raises the mechanical load on the blood vessel. Due to higher stresses, the structure of the blood vessel is altered. One example of a disease that alters blood vessel structure and consequently mechanical properties is diabetes.

An example of changes in mechanical properties due to diabetes is seen in rats after a single injection of stretozocin. Fung presents the changes in material properties based on the strain energy function shown below:. Again, we obtain the second Piola-Kirchoff stress tensor if we differentiate the strain energy function with respect to the strain:. In the rats we diabetes, Fung and colleagues measured the material constants for the above strain energy function of the thoracic aorta artery in normal rats and those 20 days after the onset of diabetes.

Although he did not report changes in tissue structure in the text, he noted profound changes in the nonlinear stress strain curve and the material constants in the strain energy function for the diabetic rats, with their aorta becoming stiffer, as shown below:. You will also note that the constants in the strain energy function change significantly. This indicates that we can use the material constants in proposed strain energy functions to quantify changes in blood vessel function due to changes in structure.

Thus, the strain energy function becomes a conduit to quantify structure-function of soft collagenous tissues just as the anisotropic Hooke's law is a way to quantify bone structure function relationships. As we mentioned, increase in vessel mechanical stress due to increased blood pressure can cause changes in tissue structure and mechanical properties.

Fung and Liu performed an experiment where they puts rats in a low oxygen chamber, similar to changes due to elevation. Nitrogen was added so that the total pressure was the same as that at sea level. They found that the systolic blood pressure increased from 2. After one month, the pressure rose to 4. Histologically , they note significant changes in tissue structure of the pulmonary artery even after a few days.

Even after a few hours, there are histological staining changes that indicate a change in the total amount of elastin in the vessel. After 12 hours, there is a significant thickening of the media layer in the pulmonary artery. After 96 hours the adventia has also experienced a significant increase in thickness. The histological changes that Fung saw are shown below:. In terms of mechanical properties, Fung reported the change in opening angle of the artery, a measure of the change in residual stress.

They note that early after exposure to higher pressure, the residual stress in the artery was greater than that of the controls. However, after prolonger exposure, the residual stress, as measured by the opening angle decreased, indicating that the adaptation changes had reduced the residual stress. Bone Structure. We start our section on tissue structure function and mechanically mediated tissue adaptation with bone tissue.

This is for two reasons: 1 from a mechanical standpoint, bone is historically the most studied tissue, and 2 due to 1 and the simpler behavior of bone compared to soft tissues, more is known about bone mechanics in relation to its structure. Bone is also a good starting point because it illustrates the principle of hierarchical structure function that is common to all biological tissues. In this section, we illustrate the anatomy and structure of bone tissue as the basis for studying tissue structure function and mechanically mediated tissue adaptation.

We first begin by describing the hierarchical levels of bone structure anatomy and then describe how these levels are constructed by bone cells removing and adding matrix physiology. Cortical Bone versus Trabecular Bone Structure. Bone in human and other mammal bodies is generally classified into two types 1: Cortical bone, also known as compact bone and 2 Trabecular bone, also known as cancellous or spongy bone. These two types are classified as on the basis of porosity and the unit microstructure.

Cortical bone is found primary is found in the shaft of long bones and forms the outer shell around cancellous bone at the end of joints and the vertebrae.

A schematic showing a cortical shell around a generic long bone joint is shown below:. The basic first level structure of cortical bone are osteons. It is found in the end of long bones see picture above , in vertebrae and in flat bones like the pelvis. Its basic first level structure is the trabeculae. Hierarchical Structure of Cortical Bone. As with all biological tissues, cortical bone has a hierarchical structure.

This means that cortical bone contains many different structures that exist on many levels of scale. The hierarchical organization of cortical bone is defined in the table below:. Cortical Bone Structural Organization. Table 1. Cortical bone structural organization along with approximate physical scales.

The parameter h is a ratio between the level i and the next most macroscopic level i - 1. This parameter is used in RVE analysis. There are two reasons for numbering different levels of microstructural organization.

First, it provides a consistent way to compare different tissues. Second, it provides a consistent scheme for defining analysis levels for computational analysis of tissue micromechanics. This numbering scheme will later be used to define analysis levels for RVE based analysis of cortical bone microstructure. The 1st and 2nd organization levels reflect the fact that different types of cortical bone exist for both different species and different ages of different species.

Note that at the most basic or third level, all bone, to our current understanding, is composed of a type I collagen fiber-mineral composite. Conversely, all bone tissue for the purpose of classic continuum analyses is considered to be a solid material with effective stiffness at the 0th structure.

In other words, a finite element analysis at the whole bone level would consider all cortical bone to be a solid material. Different types of cortical bone can first be differentiated at the first level structure. However, different types of first level structures may still contain common second level entities such as lacunae and lamellae.

We next describe the different types of 1st level structure based on the text by Martin and Burr As you will see, the different structural organizations at this level are usually associated with either a specific age, species, or both. As discussed by Martin and Burr , there are four types of different organizations at what we have described as the 1 st structural level.

These four types of structure are called woven bone, primary bone, plexiform bone, and secondary bone. A general view of cortical bone structure showing some of the 1st and 2nd level structures is shown below:.

Woven cortical bone is better defined at the 1st structural level by what it lacks rather than by what it contains. For instance, woven bone does not contain osteons as does primary and secondary bone, nor does it contain the brick-like structure of plexiform bone Fig.

Woven bone is thus the most disorganized of bone tissue owing to the circumstances in which it is formed. Woven bone tissue is the only type of bone tissue which can be formed de novo, in other words it does not need to form on existing bone or cartilage tissue. Woven bone tissue is often found in very young growing skeletons under the age of 5.

It is only found in the adult skeleton in cases of trauma or disease, most frequently occurring around bone fracture sites. Woven bone is essentially an SOS response by the body to place a mechanically stiff structure within a needy area in a short period of time.

As such, woven bone is laid down very rapidly which explains its disorganized structure. It generally contains more osteocytes bone cells than other types of bone tissue. Woven bone is believed to be less dense because of the loose and disorganized packing of the type I collagen fibers Martin and Burr, It can become highly mineralized however, which may make it somewhat more brittle than other cortical bone tissue with different level one organization.

Very little is known, however, about the mechanical properties of woven bone tissue. Christel et al. Direct measurements of woven bone tissue stiffness have not been made. Like woven bone, plexiform bone is formed more rapidly than primary or secondary lamellar bone tissue. However, unlike woven bone, plexiform bone must offer increased mechanical support for longer periods of time.

Because of this, plexiform bone is primarily found in large rapidly growing animals such as cows or sheep. Plexiform bone is rarely seen in humans. Plexiform bone obtained its name from the vascular plexuses contained within lamellar bone sandwiched by nonlamellar bone Martin and Burr, In the figure below from Martin and Burr lamellar bone is shown on the top while woven bone is shown on the bottom:.

Plexiform bone arises from mineral buds which grow first perpendicular and then parallel to the outer bone surface. This growing pattern produces the brick like structure characteristic of plexiform bone.

Each "brick" in plexiform bone is about microns m m across Martin and Burr, Plexiform bone, like primary and secondary bone, must be formed on existing bone or cartilage surfaces and cannot be formed de novo like woven bone. Because of its organization, plexiform bone offers much more surface area compared to primary or secondary bone upon which bone can be formed.

This increases the amount of bone which can be formed in a given time frame and provided a way to more rapidly increase bone stiffness and strength in a short period of time.

While plexiform may have greater stiffness than primary or secondary cortical bone, it may lack the crack arresting properties which would make it more suitable for more active species like canines dogs and humans. When bone tissue contains blood vessels surrounded by concentric rings of bone tissue it is called osteonal bone. The structure including the central blood vessel and surrounding concentric bone tissue is called an osteon.

What differentiates primary from secondary osteonal cortical bone is the way in which the osteon is formed and the resulting differences in the 2 nd level structure.

Primary osteons are likely formed by mineralization of cartilage, thus being formed where bone was not present. As such, they do not contain as many lamellae as secondary osteons. Also, the vascular channels within primary osteons tend to be smaller than secondary osteons. For this reason, Martin and Burr hypothesized that primary osteonal cortical bone may be mechanically stronger than secondary osteonal cortical bone.

Secondary osteons differ from primary osteons in that secondary osteons are formed by replacement of existing bone. Secondary bone results from a process known as remodeling. Together this forms a bursa sac , which provides a cushion for and nutrients to the surrounding bone.

Ligaments are found throughout the body. Some help connect bones at joints, while others help to stabilize two parts of the body and restrict movement between the two, like the ligaments of the womb which keep it in the right position in the pelvis or the ligaments in the bones and forearms that keep them from pulling apart.

Most ligaments are contained around moveable joints, which include:. But some are contained around immovable bones like ribs and the bones that make up the forearm. Ligaments attach bones to other bones, especially at the joints and allow you to move freely, easily, and without pain. Most ligaments run at different angles to the bone and muscles that they support and provide stability throughout the joints full range of motion. Ligaments differ based on the anatomical structure they support.

Some are stretchy while others are sturdy. No matter the case, ligaments provide stability to organs and bones throughout the body and are integral to maximal range of motion, smooth movements and pain-free mobility.

The two ligaments of the elbow are the:. These two ligaments work together not only to help stabilize the elbow joint but to also allow you to flex and extend your arm. There are five major shoulder ligaments that keep the shoulder in place and prevent it from dislocating. The five ligaments are contained within the glenohumeral and acromioclavicular joint spaces of the shoulder. The glenohumeral ligaments help to stabilize the glenohumeral joint which connects the shoulder socket, or glenoid, to the arm bone, or humerus.

The glenohumeral ligaments help us to extend our arm from the shoulder blade. The acromioclavicular AC joint, which is plane joint that connects the upper part of the shoulder blade to the collarbone, or clavicle, and allows for three degrees of freedom, or more simply allows the upper arm to glide in multiple directions.

This flexibility also makes the shoulder more prone to injury. If you have ever twisted or sprained your ankle, you probably injured your anterior talofibular ligament. This is one of three ligaments that make up the lateral collateral ligament complex LCL on the outer portion of the ankle.

The other two ligaments are the calcaneofibular and the posterior talofibular ligaments. These ligaments can be damaged if you have a severe sprain or ankle fracture. The medial collateral ligaments MCL , also known as the deltoid ligament, are located on the inside portion of the ankle.

This group of ligaments is divided into a superficial and deep group of fibers. The MCL is covered by tendons that shield it from trauma and injury. The hip contains four major ligaments and is divided into outer capsular ligaments and inner-capsular ligaments.

They both assist in the flexion and extension of the hip. The three capsular ligaments include:. The sole intracapsular ligament is the ligamentum teres ligament of the head of the femur that serves as a carrier for the foveal artery, a major blood supply source in babies and young children.

There are 7 ligaments that support the spine:. The posterior and anterior longitudinal ligaments are the major contributors to the spine's stability. Injury to the posterior longitudinal ligament can result in disc herniation, which may render you unable to flex backward without pain. If your back goes out, especially if you suddenly hyperflex or twist your back, you may have injured one or more of these back ligaments.

If you have ever had back pain, you know how painful and debilitating it can be. In fact, back pain due to ligament sprains and strains are one of the leading causes of back pain in the world. 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.

Some of the most common ligament injuries include:. An ACL tear is by far the most common knee injury and ligament tear that you may hear about. During an ACL tear, you may hear a pop and feel immediate instability in the knee. The knee is a highly vascularized area so rupture of the ACL leads to rapid inflammation due to blood pouring into the knee space causing a hemarthrosis.

Most of the pain felt during an ACL tear is due to inflammation. An ACL tear was once thought to be a career-ending knee injury for an athlete, but that is no longer the case due to many surgical advances. An ACL tear can lead to:. It may lead to the loss of an entire season or lack of sports participation among young athletes. It is also associated with long-term clinical sequelae including:.