is the meniscus avascular

Full Answer

Is meniscus avascular tissue?

The inner region of the meniscus is avascular, aneural, and alymphatic tissue, which is why, similar to cartilage, its repair capacity is lower than that of the outer region. Cells in the inner region are chondrocyte-like fibrochondrocytes, and its matrix contains many similar components common to cartilage and tendon.

Does the meniscus have blood flow?

The blood flow to the meniscus is very poor. Blood is what brings nutrients, growth factors and cells to the meniscus and allow it to heal. Since the meniscus has a limited blood supply, certain parts of the meniscus are more likely to heal tears and other areas can never heal.

Which part of meniscus has blood supply?

The anterior and posterior homs of the menisci have a rich supply of both blood vessels and nerves.

What type of joint is the meniscus?

A meniscus is a crescent-shaped fibrocartilaginous anatomical structure that, in contrast to an articular disc, only partly divides a joint cavity....Meniscus (anatomy)MeniscusLeft knee-joint from behind, showing interior ligamentsDetailsIdentifiersLatinMenisci6 more rows

Can a torn meniscus cause poor circulation?

The menisci are nourished by small blood vessels, but also have a large area in the center of the meniscus that has no direct blood supply (it is avascular). This lack of circulation presents a problem when there is an injury to the meniscus, as the avascular areas tend not to heal.

Is the ACL vascular?

The major blood supply of the ACL arises from the middle geniculate artery. The distal part of the ACL is vascularized by branches of the inferior geniculate artery. The ligament is covered by a synovial fold where the terminal branches of the middle and the inferior geniculate artery form a periligamentous network.

What portion of the meniscus is avascular?

The inner two-thirds of the meniscus is what we consider avascular, where minimal to no blood supply reaches the tissue.

What part of the meniscus loses it's vascularity as we get older?

Left: Though fully vascularized at birth, the blood vessels in the meniscus recede during maturity. In adulthood, the red-red region contains the overwhelming majority of blood vessels.

Are there nerves in the meniscus?

Symptoms of meniscus tear Because the menisci have no nerve endings, pain associated with a tear is actually due to swelling and injury to the surrounding tissue.

Is the meniscus intra articular?

Introduction: Menisci and cruciate ligaments are intra-articular structures of knee, and injury to these structures is common.

What is the meniscus of the knee made of?

A meniscus is a piece of cartilage found where two bones meet (joint space). Menisci (plural of meniscus) protect and cushion the joint surface and bone ends. In the knee, the crescent-shaped menisci are positioned between the ends of the upper (femur) and lower (tibia) leg bones.

Is meniscus articular cartilage?

1 The meniscus is not attached to the bone like articular cartilage. Instead, it sits between the bone ends to cushion the joint. The purpose of both types of cartilage is to protect the knee joint by keeping the bones from rubbing together. They also help the knee move smoothly.

How do I increase blood flow to a torn meniscus?

Gentle massage around the injured knee area or small flexing or extending knee movements (if not painful) will also help increase blood flow, oxygen, nutrients, and will prevent stiffness.

Which meniscus is more vascular?

Arnoczky has the best evidence for blood supply with the meniscus with the india ink pathology slides showing that the periphery is substantially more vascular then the central portion of the meniscus which is why repairs fail in that region. Vascularization of the meniscus arrive from the adjacent joint capsule.

How do you increase blood flow to the knee cartilage?

Massage your muscles and tissues around the joint and above it. This will help blood flow and joint fluid flow to the joint. For example, with knee pain, take the time to massage your thigh, especially the inner and back of the thigh. This helps blood flow to the knee.

What is the red zone of the meniscus?

The outside 1/3 of each meniscus has a rich blood supply and is sometimes referred to as the 'red zone. ' A tear in this red zone can often heal on its own or be repaired surgically. The remaining 2/3 of each meniscus lacks blood supply.

What are the cells in the meniscal tissue?

There are three types of cells within the meniscal tissue. The cells located at the peripheral part are oval- or spindle-shaped cells which resemble fibroblasts morphologically. They possess thin, long, cytoplasmic processes which are used to communicate with other cells and extracellular matrix. These cells have abundant cytoplasm which is rich in granular endoplasmic reticulum and Golgi apparatus. They do not have pericellular matrix; instead, the collagen fibers of the extracellular matrix (which are mainly type I but to a lesser extent types III and V) surround these fibroblast-like cells. The cells of the inner menisci are more oval in shape and are surrounded by pericellular matrix. Owing to their resemblance to chondrocytes, they are called fibrochondrocytes or chondrocyte-like cells. The extracellular matrix around them contains mostly type II collagen, besides much less but significant amounts of type I collagen and glycosaminoglycan more than the outer menisci. Considering the fact that this part of the meniscus contains type II collagen and aggregan which is a proteoglycan, it resembles hyaline articular cartilage. The third type of cells is the ones located at the superficial part of the meniscus which is spindle shaped similar to the fibroblast-like cells but flatter than them and does not possess cytoplasmic processes. They are considered as progenitor cells with certain capabilities [ 25, 28, 37, 54 ].

What is the vascular pattern of the meniscus?

The menisci of an adult knee are relatively avascular structures, and their vascular pattern is strongly related to its healing capacity. According to their vascularization, adult meniscus is divided into three zones. The outermost one third of it is regarded as the “red–red zone” which has an abundant blood supply. The middle one third part, named as the “red–white zone,” has a scarce vascularization when compared with the red–red zone. The innermost one third is the avascular “white–white zone” (Fig. 24.3 ). When compared to its body, the insertion sites have richer vascularization [ 37 ].

What happens to the menisci during the gestational period?

During the gestational period, the developing menisci are highly cellular in the beginning and the nucleus–cytoplasm ratio is high . In time, these cells mature and the nucleus–cytoplasm ratio declines. While the number of cells decreases, their collagen production increases. Collagen fibers begin to orient in a circumferential manner.

What is a complete tear?

Complete tears are further classified as stabile and unstable tears. Meniscal tears are also classified according to the type of tear: vertical/longitudinal, radial/transverse, or horizontal/complex tears. Radial tears of the posteromedial part of the medial meniscus are the most common.

Where is the posterior horn of the lateral meniscus attached?

The posterior horn of the lateral meniscus is attached to the lateral part of the medial femoral condyle via anterior (Humphrey) and posterior (Wrisberg) meniscofemoral ligaments. The anterior meniscofemoral ligament passes anterior to PCL, and posterior to it, there is the posterior meniscofemoral ligament.

Which nerve is responsible for innervation of the medial meniscus?

Posterior articular branch of tibial nerve is responsible for most of the innervation of the meniscus. Medial articular branch of saphenous nerve also contributes to the innervation of the medial meniscus [ 15 ]. The larger nerves have a circumferential pattern in the perimeniscal tissue accompanying blood vessels.

When does the meniscus lose its vascularity?

Meniscus vascularity. During the gestational period, the whole meniscus is vascular. After birth, the inner part starts to lose its vascularity due to endostatin accumulation. Around the 11 years of age, the inner part becomes avascular (Reprinted from Springer Cellular and Molecular Bioengineering, Sanchez-Adams and Athanasiou [ 57 ], figure 3, with kind permission from Springer Science and Business Media)

What is the menisci of the knee?

The menisci of the knee are two pads of fibrocartilaginous tissue which serve to disperse friction in the knee joint between the lower leg ( tibia) and the thigh ( femur ). They are concave on the top and flat on the bottom, articulating with the tibia.

How many surgeries are there for meniscus tear?

Two surgeries of the meniscus are most common. Depending on the type and location of the tear, the patient's age, and physician's preference, injured menisci are usually either repaired or removed, in part or completely (meniscectomy). Each has its advantages and disadvantages.

What are the different types of meniscus tears?

There are two general types of meniscus injuries: acute tears that are often the result of trauma or a sports injury and chronic or wear-and-tear type tears. Acute te ars have many different shapes (vertical, horizontal, radial, oblique, complex) and sizes.

What is the shape of a meniscus?

Meniscus (anatomy) For other uses, see Meniscus (disambiguation). A meniscus is a crescent-shaped fibrocartilaginous anatomical structure that, in contrast to an articular disc, only partly divides a joint cavity. In humans they are present in the knee, wrist, acromioclavicular, sternoclavicular, and temporomandibular joints;

What is the function of menisci?

The menisci act to disperse the weight of the body and reduce friction during movement. Since the condyles of the femur and tibia meet at one point (which changes during flexion and extension ), the menisci spread the load of the body's weight. This differs from sesamoid bones, which are made of osseous tissue and whose function primarily is to protect the nearby tendon and to increase its mechanical effect.

What is conservative management?

Conservative management is often considered first for a smaller or chronic tear that does not appear to require surgical repair. It consists of activity modification or physical therapy to strengthen and increase the range of motion.

Is it difficult to heal a meniscus?

Many studies show the meniscus serves a purpose and therefore doctors will attempt to repair when possible. However, the meniscus has poor blood supply, and , therefore, healing can be difficult.

Why is articular cartilage important?

The articular cartilage is important in your body because if the articular cartilage starts to break down, it directly puts more strain on the bone, which can increase your risk of osteoarthritis . You can break up the meniscus into three zones, the anterior horn, the body, and the posterior horn.

What is the first thing people think of when a runner starts to have knee pain?

Once a runner starts developing knee pain, the meniscus is usually the first thing people think of. Next week we'll discuss some different ways I use to help differentiate if an injury involves the meniscus or another tissue that could be causing the pain. Russ.

What is the function of the meniscus in the knee?

The main function of the mensicii are to shock absorb and distribute forces more efficiently in the knee.

Why does the meniscus run into problems?

One of the problems the meniscus runs into is that because it is a cartilage, it lacks a certain amount of blood flow to the tissue for proper healing properties. If you broke up the meniscus into thirds, the outer third gets some blood flow, but it is still very limited.

What is the inner two thirds of the meniscus?

The inner two-thirds of the meniscus is what we consider avascular , where minimal to no blood supply reaches the tissue. The picture below shows zones where the blood flow is present and where the blood flow is very limited (they use the terms red and white zone to determine circulation).

Can running cause a tear in the meniscus?

Over time, if your muscles fatigue and aren't able to stabilize the joint properly, that repetitive strain can cause the meniscus to become more vulnerable to a possible tear.

What is a horizontal tear?

Horizontal Tear: A horizontal tear is a tear that is most commonly amenable to meniscus repair. 3  Seen in the upper right corner of the image, a horizontal tear runs along the circumferential fibers of the meniscus.

What are the factors that determine the best treatment for a meniscus tear?

Some of these factors include the age of the patient, results of nonsurgical treatment, and if there is other damage than just a torn meniscus. 1  In addition, the specific type of meniscus tear can determine the most appropriate treatment. ...

What causes knee pain in 2020?

Updated on June 24, 2020. Verywell / Gary Ferster. Meniscus tears are a common cause of knee pain and many people end up with arthroscopic knee surgery for their condition.

What is a radial tear?

Radial Tear: Radial tears of the meniscus, pictured in the middle of the top row on the image, are the most common type of meniscus tear. 4  These tears are within the avascular zone of the meniscus, where there is no blood supply, and therefore there is little capacity for these tears to heal. Therefore, when these tears come to requiring ...

Can a meniscus tear be repaired?

Typically complex tears are not treated with meniscus repair because of the complex nature of the tear. In some unusual circumstances, some of the torn meniscus can be removed, while other portions can be repaired.

Where are the horn tears located?

Posterior horn tears are much more common and located in the back of the meniscus. Central tears are located on the inner side of the meniscus. This is a part of the meniscus without vascular blood supply and therefore not amenable to repair. Peripheral tears are located further on the outside of the meniscus, and these are the types ...

Can meniscus tears be sewn together?

Rather than removing the damaged portion of the meniscus, a horizontal tear may be able to be sewn together. 6  The key to determining the treatment of these tears is their location.

Where does the vascular supply of the meniscus come from?

The vascular supply of the menisci originates predominately from the inferior and superior lateral and medial genicular arteries. During the first year of life the meniscus contains blood vessels throughout its body but when the weight bearing starts the vascularity and the circulatory network diminish and only 25-33% area remain vascular by the capillaries of the capsule and synovial membrane. The vascularity diminishes so much that in 4th decade of life only the periphery is vascular whereas the center of the menisci is avascular. The center portion is completely dependent upon the synovial fluid diffusion for nutrition . The central avascular portion of menisci either does not heal completely or heal at all after injury.

What is the lateral meniscus?

Anatomy and attachment. The lateral meniscus is almost circular and covers a larger portion of the tibial articular surface than the medial meniscus. The lateral meniscus is consistent in width throughout its course. The anterior horn of the lateral meniscus blends into the attachment of the anterior cruciate ligament, ...

Why are my menisci rubbery?

The rubbery texture of the menisci is due to their fibrocartilagenous structure. Their shape is maintained by the collagen within them. One meniscus is on the inner side of your knee--the medial meniscus. The other meniscus is on the outer side of your knee - the lateral meniscus.

What causes a meniscus tear?

A slow twisting force may also cause the tear.Damage to the meniscus is due to rotational forces directed to a flexed knee (as may occur with twisting sports) is the usual underlying mechanism of injury.

What is the role of menisci in the knee?

At knee joint the menisci plays a major role in congurency of the joint. Menisci forms the concavity in which the femoral condyles sits. Menisci rests between the thigh bone femur and the tibia and there are two knee joint ligaments. They are a type of cartilage in the joint.

What is the difference between the anterior horn and the posterior horn?

The anterior horn of the lateral meniscus blends into the attachment of the anterior cruciate ligament, whereas the posterior horn attaches just behind the intercondylar eminence, often blending into the posterior aspect of the ACL. There is no attachment of the lateral meniscus to the LCL.

Which is more mobile, the medial or lateral meniscus?

The capsular components attach the lateral meniscus to the tibia less firmly than the medial meniscus. The lateral menis cus is more mobile than the. medial meniscus, and has a range of movement that may be as great as 10 mm (0.4 in) in an anteroposterior direction.

What causes a meniscus tear?

The most common mechanism of menisci injury is a twisting injury with the foot anchor on the ground, often by another player's body. A slow twisting force may also cause the tear.Damage to the meniscus is due to rotational forces directed to a flexed knee (as may occur with twisting sports) is the usual underlying mechanism of injury . The meniscal tear is of following types:

Why are my menisci rubbery?

The rubbery texture of the menisci is due to their fibrocartilagenous structure. Their shape is maintained by the collagens within them. One meniscus is on the inner side of your knee--the medial meniscus. The other meniscus is on the outer side of your knee--the lateral meniscus.

What is the pain in the medial joint line?

Pain in the area of the medial joint line during hyperflexion of the knee joint. Pain during external rotation of the foot and the lower leg when the knee is flexed at different angles around 70–90°. Weakened or hypotrophied quadriceps muscle.

Why is the medial meniscus attached to the medial collateral ligament?

This is partly because the medial meniscus is attached to the medial collateral ligament, and partly because tackles are often directed towards the lateral side of the knee, causing external rotation of the tibia. Injury to the medial meniscus is about 5 times more common than injury to the lateral meniscus.

What are the three mechanoreceptors in the meniscal body?

NERVE SUPPLY: The horns of the menisci and the peripheral vascularized portion of the meniscal bodies are well innervated with free nerve endings (nociceptors) and three different mechanoreceptors (Ruffini corpuscles, pacinian corpuscles, and Golgi tendon organs).

How long is the medial meniscus?

The medial meniscus is approximately 1.4 in (3.5cm) in length. The anterior horn of the medial meniscus is attached to the anterior surface of the tibia well off the tibial plateau. The anterior fibers of the anterior cruciate attachment merge with the transverse ligament, which connects the anterior horns of the medial.

What is the role of menisci in the knee?

At knee joint the menisci plays a major role in congurency of the joint. Menisci forms the concavity in which the femoral condyles sits. Menisci rests between the thigh bone femur and the tibia and there are two knee joint ligaments. They are a type of cartilage in the joint.

Overview

Structure

The menisci of the knee are two pads of fibrocartilaginous tissue which serve to disperse friction in the knee joint between the lower leg (tibia) and the thigh (femur). They are concave on the top and flat on the bottom, articulating with the tibia. They are attached to the small depressions (fossae) between the condyles of the tibia (intercondyloid fossa), and towards the center they are unattached and their shape narrows to a thin shelf. The blood flow of the meniscus is from the p…

Function

Clinical significance

Etymology

See also