How the knee joint works. The structure of the human knee joint, valgus and varus deformity

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Knee joint (Articulatio genus, Articulatio genus)– this is a complex osteochondral formation, consisting of many different elements, thanks to which the joint becomes mobile, functional and, at the same time, susceptible to many injuries. Let's figure out what the structure is knee joint.

As the anatomical atlas with photos shows us, the knee joint is trochlear-spherical in shape. In the unbent state, it works like a block-shaped one. The knee joint is formed by three bones: the distal (lower) epiphysis femur, proximal (upper) epiphysis of the tibia and patella (approx. epiphysis is the rounded end section of the tubular bone that forms the joint).

The articular surface of the condyles (protrusions on the bony epiphysis) of the femur has an ellipsoidal shape, with the medial condyle larger than the lateral one. The shape of the condyles of the femur does not coincide with the shape of the condyles of the tibia, since the latter have a different curvature. This discrepancy is corrected by the medial and lateral meniscus, which is located between the femoral and tibial condyles.

The meniscus is a triangular cartilaginous plate, varying in shape and size. They are designed in such a way that the lateral (outer) edge is thickened and fuses with the articular capsule, as shown in the figure. The medial (inner) free edge is pointed and faces the joint cavity. The meniscus is attached anteriorly and posteriorly to the intercondylar eminence of the tibia. The transverse knee ligament connects the anterior edges of both menisci.

The articular capsule is of great importance in the knee joint. Most often this is the reason pain in the knee, limiting a person’s movement (note that the joint itself, in principle, cannot hurt, since there are no nerve endings there). As the picture shows us, the joint capsule is attached to the edge of the femur under the epicondyles, to the edge of the tibia and the patella. It is attached to the patella in such a way that its anterior surface is outside the joint cavity. Structure of the joint capsule: inside it there is a synovial membrane that lines the surface of the articulating bones to the line of articular cartilage.

The articular capsule of the knee joint forms a series of synovial bursae that lie along the muscles and tendons, but they do not communicate with the joint cavity itself. The largest bursa is the suprapatellar bursa, and it is located between the quadriceps tendon and femur.

Knee ligaments

The knee joint is supported by ligaments, which are usually divided into two groups:

extracapsular (ligaments located outside the joint cavity);
intracapsular (ligaments inside the joint).

External ligaments include:

The tibial collateral ligament, which originates from the medial condyle of the femur and runs downward, fuses with the joint capsule and medial meniscus, reaching the proximal epiphysis of the tibia;
The fibular collateral ligament, somewhat narrower than the previous one, runs down from the lateral epicondyle of the femur and attaches to the lateral surface of the head of the fibula.
Patellar ligament. Essentially, the patellar ligament is an extension of the quadriceps tendon. The tendon of this muscle approaches the patella, covers it on all sides, and continues downward, reaching the tibia. Some of the bundles of this tendon that reach the tibial tuberosity are called the patellar ligament.
Lateral and medial suspensory ligament. It is also a continuation of the quadriceps tendon, but these bundles are directed from the patella to the external and internal condyles of the tibia.
Supporting ligaments of the patella. Attached to the epicondyles of the femur. As their name suggests, these ligaments play an important role in holding the patella in the desired position.
Oblique and arcuate popliteal ligament. The oblique ligament strengthens the posterior parts of the joint capsule and is part of the tendon bundles of the semimembranosus muscle. The ligament originates from the medial condyle of the tibia to the lateral condyle of the femur. The arcuate arises from the external condyle of the femur and the head of the fibula, attaches to the oblique popliteal ligament and goes further to the lateral condyle of the tibia.

Internal connections include:

Cruciate ligaments. Here it is worth highlighting the anterior cruciate and posterior cruciate ligaments separately. The anterior cruciate ligament of the knee joint originates from the inner surface of the external condyle of the femur, moves forward and is inserted medially on the anterior intercondylar field of the tibia. The posterior cruciate ligament, on the other hand, originates on the medial surface of the medial condyle of the femur, runs posteriorly medially, and inserts into the posterior intercondylar field of the tibia. Regular excessive movements of the legs in the knees can lead to ruptures of the cruciate ligaments in them.
There are three other ligaments related to the meniscus: the transverse knee ligament, the anterior and posterior meniscofemoral ligament.

Muscles of the knee joint

The muscles of the knee joint provide various movements in it, thanks to which a person has the ability to move. With a fixed thigh, the knee muscles provide flexion, extension, supination and pronation (rotation) of the lower leg, and with a fixed lower leg they provide supination, pronation, and forward and backward movement of the hip.

Flexion is ensured by the following muscle group:

biceps femoris;
semitendinosus and semimembranosus femoris;
sartorius and gracilis muscles;
popliteus muscle;
calf muscle;
plantar muscle.

Extension is provided by the following muscle group;

rectus femoris muscle;
vastus lateralis and vastus medialis;
vastus intermedius muscle.

Pronation of the knee joint is ensured by the following muscles:

semitendinosus and semimembranosus;
sartorial and fine;
medial head of the gastrocnemius;
popliteal

Supination of the knee joint is provided by the biceps femoris muscle and the lateral head of the gastrocnemius.

So, in general terms, we have become familiar with the anatomy of the knee joint and what it is. And the scheme of his work and hers detailed description are offered in the following video story.

The knee joint is the largest and most complex in its structure in the human body; its anatomy is extremely complex, because it must not only support the weight of the entire owner’s body, but also allow him to perform a wide variety of movements: from dance steps to the lotus position in yoga.

Content:

knee structure

Such a complex structure, an abundance of ligaments, muscles, nerve endings and blood vessels makes the knee very vulnerable to various diseases and injuries. One of the most common reasons Injuries to this particular joint cause disability.

It consists of the following formations:

bones - femur, tibia and patella,
nerve endings and blood vessels,
cruciate ligaments.

Functions

The knee joint in its structure is close to hinge joints. This allows not only to bend and straighten the lower leg, but also to perform pronation (inward rotation) and supination (outward movement), turning the bones of the lower leg.

Also, when flexing, the ligaments relax, and this makes it possible not only to rotate the lower leg, but also to make rotational and circular movements.

Bone components

The knee joint consists of the femur and tibia, these tubular bones are connected to each other by a system of ligaments and muscles, in addition, in the upper part of the knee there is a rounded bone - the patella or kneecap.

The femur ends in two spherical formations - the femoral condyles and, together with the flat surface of the tibia, form a connection - the tibial plateau.

bone components of the knee

The patella is attached to the main bones by ligaments and is located in front of the kneecap. Its movements are ensured by sliding along special grooves on the femoral condyles - the pallofemoral recess. All 3 surfaces are covered with a thick layer of cartilage tissue, its thickness reaches 5-6 mm, which provides shock absorption and reduces thorns during movement.

Connecting components

The main ligaments, together with the bones that make up the knee joint, are the cruciate ligaments. In addition to them, on the sides there are lateral collateral ligaments - medial and lateral. Inside there are the most powerful connective tissue formations - the cruciate ligaments. The anterior cruciate ligament connects the femur and the anterior surface of the tibia. It prevents the tibia from moving forward during movement.

The posterior cruciate ligament does the same thing, preventing the tibia from moving posterior to the femur. Ligaments provide connection between bones during movement and help to maintain it; rupture of the ligaments leads to the inability to make voluntary movements and lean on the injured leg.

knee ligaments

In addition to the ligaments, in the knee joint there are two more connective tissue formations that separate the cartilaginous surfaces of the femur and tibia - menisci, which have very great importance for its normal functioning.

Menisci are often called cartilage, but in their structure they are closer to ligaments. Menisci are rounded plates of connective tissue found between the femur and the tibial plateau. They help to correctly distribute the weight of a person’s body, transferring it to a large surface and, in addition, stabilize the entire knee joint.

Their importance for the normal functioning of the joint is easy to understand by looking at the structure of the human knee - the photo makes it possible to see the menisci located between the spherical epiphysis of the femur ( bottom) and the flat surface of the tibia.

photo of meniscus

Knee muscles

The muscles located around the joint and ensuring its functioning can be divided into three main groups:

anterior muscle group - hip flexors - quadriceps and sartorius muscles,
posterior group – extensors – biceps, semimembranosus and semitendinosus muscles,
medial (inner) group - hip adductors - thin and adductor magnus muscles.

knee muscles

One of the most powerful muscles in the human body is the quadriceps. It is divided into 4 independent muscles, located on the front surface of the femur and attached to the kneecap. There, the muscle tendon turns into a ligament and connects to the tibial tuberosity. The intermedius muscle, one of the branches of the quadriceps muscle, also attaches to the knee capsule and forms the knee muscle. Contraction of this muscle promotes leg extension and hip flexion.
The sartorius muscle is also part of the muscles of the knee joint. It starts from the anterior iliac axis, crosses the surface of the femur and goes along the inner surface to the knee. There she goes around him with inside and is attached to the tibial tuberosity. This muscle is two-part and therefore participates in flexion of both the thigh and lower leg, as well as in the inward and outward movement of the lower leg.
Thin muscle - starts from the pubic joint, goes down and attaches to the knee joint. It helps with hip adduction and ankle flexion.

In addition to these muscles, the tendons of the biceps femoris, tendinous, semimembranosus and popliteus muscles pass through the knee joint. They provide adducting and abducting movements of the lower leg. The popliteus muscle is located directly behind the knee and helps with flexion and internal rotation.

Innervation and blood supply of the knee

The knee joint is innervated by rami, which divides into several parts and innervates the lower leg, foot and knee. The knee joint itself is innervated by the popliteal nerve, it is located behind it, and is divided into the tibial and peroneal branches.

knee nerves

The tibial nerve is located on the back of the leg, and the peroneal nerve is located in front. They provide sensory and motor innervation to the lower leg.

The blood supply to the knee joint is carried out using the popliteal arteries and veins, whose course follows the course of the nerve endings.

blood supply to the knee

What are the risks of injury?

Depending on which component of the knee is damaged, injuries, diseases and pathologies are classified.

It can be:
dislocations,
fractures of the bones surrounding the joint,
inflammatory and dystrophic diseases,

damage to the tissues inside and around the joint, that is, cartilage, capsules, ligaments, as well as adipose tissue.

The knee joint, along with the hip joint, is the largest and most powerful joint in the human skeleton. It unites the bones of the thigh and lower leg, which provide range of motion when walking. The joint has a complex complex structure, in which each element ensures the functioning of the knee in particular and the ability to walk in general.

The structure of the human knee joint explains the cause of emerging pathologies and helps to understand the etiology and course of inflammatory and degenerative diseases. Even small deviations from the norm in any element of the joint can cause pain and limited mobility.

Three bones of the knee joint are involved in the formation of the joint: the femur, tibia and patella. Inside the joint, on the tibial plateau, are located that increase the stability of the structure and ensure rational distribution of the load. During movement, the menisci spring - they compress and unclench, ensuring a smooth gait and protecting the articulation elements from abrasion. Despite their small size, the importance of the menisci is very great - when they are destroyed, the stability of the knee decreases and arthrosis inevitably occurs.

In addition to bones and menisci, constituent elements The joints are the articular capsule, which forms the inversions of the knee joint and the synovial bursae and ligaments. The ligaments that form the knee joint are formed by connective tissue. They fix bones, strengthen joints and limit range of motion. Ligaments provide stability to the joint and prevent movement of its structures. When injuries occur, ligaments are sprained or torn.

The knee is innervated by the popliteal nerve. It is located behind the joint and is part of the sciatic nerve that passes to the foot and leg. The sciatic nerve provides sensation and movement to the leg. The popliteal artery and vein are responsible for the blood supply, repeating the course of the nerve branches.

Structure of the knee joint

The main joint-forming elements are considered to be the following:

femoral condyles
tibial plateau
knee cap
menisci
joint capsule
ligaments

The knee joint itself is formed by the heads of the femur and tibia. The head of the tibia is almost flat with a slight depression, and it is called a plateau, in which there is a medial part, located in the midline of the body, and a lateral part.

The head of the femur consists of two large rounded spherical protrusions, each of which is called the condyle of the knee joint. The condyle of the knee joint located on the inside is called medial (internal), and the opposite one is called lateral (external). The articular heads do not match in shape, and their congruence (correspondence) is achieved due to two menisci - medial and lateral, respectively.

The articular cavity is a gap that is limited by the heads of the bones, menisci and capsule walls. Inside the cavity there is synovial fluid, which ensures optimal gliding during movement, reduces friction of the articular cartilages and nourishes them. The surfaces of the bones entering the articulation are covered with cartilage tissue.

Hyaline cartilage of the knee joint white, shiny, dense, 4-5 mm thick. Its purpose is to reduce friction between articular surfaces during movement. Healthy knee joint cartilage has a perfectly smooth surface. Various diseases (arthritis, arthrosis, gout, etc.) lead to damage to the surface of hyaline cartilage, which, in turn, causes pain when walking and limited range of motion.

Knee cap

The sesamoid bone, or patella, covers the front of the knee joint and protects it from injury. It is located in the tendons of the quadriceps muscle, has no fixation, is mobile and can move in all directions. Top part The patella has a rounded shape and is called the base, the elongated lower part is called the apex. On the inside of the knee is goose foot- the junction of the tendons of 3 muscles.

Joint capsule

The bursa of the knee joint is a fibrous sheath that limits the outside of the articular cavity. It is attached to the tibia and femur bones. The capsule has low tension, which ensures a large range of motion in the knee in different planes. The joint capsule nourishes the articulation elements, protects them from external influences and wear. The posterior section of the capsule, located on the inside of the knee, is thicker and resembles a sieve - blood vessels pass through numerous holes, and blood supply to the joint is ensured.

The capsule of the knee joint has two membranes: internal synovial and external fibrous. The dense fibrous membrane performs protective functions. It has a simple structure and is firmly fixed. The synovial membrane produces a fluid that is appropriately named. It is covered with small outgrowths - villi, which increase its surface area.

In places of contact with the bones of the articulation, the synovial membrane forms a small protrusion - inversion of the knee joint. In total, there are 13 inversions, which are classified depending on their location: medial, lateral, anterior, inferior, superior inversion. They increase the cavity of the joint, and in pathological processes they serve as places for the accumulation of exudate, pus and blood.

Knee joint bags

Are important addition, thanks to which muscles and tendons can move freely and painlessly. There are six main bags, which look like small slit-like cavities formed by the tissue of the synovial membrane. Inside they contain synovial fluid and may communicate with the articulation cavity or not. Bags begin to form after a person is born, under the influence of loads in the area of the knee joint. With age, their number and volume increase.

Biomechanics of the knee

The knee joint provides support for the entire skeleton, bears the weight of the human body and experiences the greatest load when walking and moving. It performs many different movements, and therefore has complex biomechanics. The knee is capable of flexion, extension and circular rotational movements. The complex anatomy of the human knee joint ensures its wide functionality, coordinated work of all elements, optimal mobility and shock absorption.

Pathologies of the knee joint

Pathological changes in the musculoskeletal system can be caused by congenital pathology, injuries and diseases. The main signs indicating the presence of violations are:

inflammatory process;
painful sensations;
limitation of mobility.

The degree of damage to the elements of the articulation, coupled with the cause of their occurrence, determines the localization and intensity of the pain syndrome. Pain can be diagnosed periodically, be constant, appear when trying to bend/extend the knee, or be a consequence of physical activity. One of the consequences of ongoing inflammatory and degenerative processes is deformation of the knee joint, leading to serious illnesses including disability.

Anomalies of the development of the knee joint

There is valgus and varus deformity of the knee joints, which can be congenital or acquired. Diagnosis is made using x-ray. Normal legs standing man straight and parallel to each other. With valgus deformity of the knee joint, they are curved - on the outside, an open angle appears in the knee area between the lower leg and the thigh.

The deformity may affect one or two knees. With bilateral curvature, the legs resemble the letter “X” in shape. Varus deformity of the knee joints bends the bones in the opposite direction and the shape of the legs resembles the letter “O”. With this pathology, the knee joint develops unevenly: the joint space decreases on the inside and widens on the outside. Then the changes affect the ligaments: the outer ones stretch, and the inner ones atrophy.

Each type of curvature is a complex pathology that requires complex treatment. If left untreated, the risk of excessive knee mobility, habitual dislocations, severe contractures, ankylosis and spinal pathologies is quite high.

Hallux valgus and varus deformity in adults

It is an acquired pathology and most often appears with deforming arthrosis. In this case, the cartilage tissue of the joint undergoes destruction and irreversible changes, leading to loss of mobility of the knee. Also, deformation can be a consequence of injuries and inflammatory-degenerative diseases that cause changes in the structure of bones, muscles and tendons:

compound fracture with displacement;
ligament rupture;
habitual knee dislocation;
immune and endocrine diseases;
arthritis and arthrosis.

In adults, treatment of a deformed knee joint is inextricably linked to the underlying cause and is symptomatic. Therapy includes the following points:

painkillers;
NSAIDs - non-steroidal anti-inflammatory drugs;
glucocorticosteroids;
vasoregulating drugs and venotonics;
chondroprotectors;
physiotherapeutic treatment;
massage.

Drug treatment is aimed at eliminating pain, restoring cartilage, improving metabolism and tissue nutrition, and maintaining joint mobility.

Valgus and varus deformity in children

Acquired varus or valgus deformity of the knee joints in children, which appears by 10-18 months, is associated with deviations in the formation musculoskeletal system child. As a rule, the deformity is diagnosed in weakened children with muscle hypotonia. It appears as a result of stress on the legs against the background of a weak muscular-ligamentous system. The cause of such a deviation may be prematurity of the child, intrauterine malnutrition, congenital weakness of connective tissue, general weakness of the body, or previous rickets.

The cause of the secondary pathology that causes abnormalities in the formation of the knee joint is neuromuscular diseases: polyneuropathy, cerebral palsy, muscular dystrophy, poliomyelitis. Deformation of the joint not only causes curvature of the legs, but also has an extremely detrimental effect on the entire body.

Quite often the feet and hip joints suffer, and with age, flat feet and coxarthrosis develop.

Treatment of hallux valgus and varus deformity in children includes:

load limitation;
wearing orthopedic shoes;
use of orthoses and splints;
massage;
physiotherapy, most often paraffin wraps;
physical therapy classes.

Conclusion

Having a complex structure, the knee joint bears a large load and performs many functions. It is a direct participant in walking and affects the quality of life. Paying attention to your body and taking care of the health of all its constituent elements will help you avoid knee pain and maintain an active lifestyle for a long time.

Such a complex structure, an abundance of ligaments, muscles, nerve endings and blood vessels makes the knee very vulnerable to various diseases and injuries. One of the most common causes of disability is injuries to this joint.

It consists of the following formations:

bones - femur, tibia and patella,
muscles,
nerve endings and blood vessels,
menisci,
cruciate ligaments.

Also, when flexing, the ligaments relax, and this makes it possible not only to rotate the lower leg, but also to make rotational and circular movements.

Bone components

The femur ends in two spherical formations - the femoral condyles and, together with the flat surface of the tibia, form a connection - the tibial plateau.

bone components of the knee

The patella is attached to the main bones by ligaments and is located in front of the kneecap. Its movements are ensured by sliding along special grooves on the femoral condyles - the pallofemoral recess. All 3 surfaces are covered with a thick layer of cartilage tissue, its thickness reaches 5-6 mm, which provides shock absorption and reduces thorns during movement.

Connecting components

In addition to the ligaments, the knee joint contains two more connective tissue formations that separate the cartilaginous surfaces of the femur and tibia - the menisci, which are very important for its normal functioning.

Menisci are often called cartilage, but in their structure they are closer to ligaments. Menisci are rounded plates of connective tissue found between the femur and the tibial plateau. They help to correctly distribute the weight of a person’s body, transferring it to a large surface and, in addition, stabilize the entire knee joint.

Knee muscles

The muscles located around the joint and ensuring its functioning can be divided into three main groups:

anterior muscle group - hip flexors - quadriceps and sartorius muscles,
posterior group – extensors – biceps, semimembranosus and semitendinosus muscles,
medial (inner) group - hip adductors - thin and adductor magnus muscles.

knee muscles

One of the most powerful muscles in the human body is the quadriceps. It is divided into 4 independent muscles, located on the front surface of the femur and attached to the kneecap. There, the muscle tendon turns into a ligament and connects to the tibial tuberosity. The intermedius muscle, one of the branches of the quadriceps muscle, also attaches to the knee capsule and forms the knee muscle. Contraction of this muscle promotes leg extension and hip flexion.
The sartorius muscle is also part of the muscles of the knee joint. It starts from the anterior iliac axis, crosses the surface of the femur and goes along the inner surface to the knee. There it goes around it from the inside and attaches to the tuberosity of the tibia. This muscle is two-part and therefore participates in flexion of both the thigh and lower leg, as well as in the inward and outward movement of the lower leg.
Thin muscle - starts from the pubic joint, goes down and attaches to the knee joint. It helps with hip adduction and ankle flexion.

Innervation and blood supply of the knee

The knee joint is innervated by branches of the sciatic nerve, which is divided into several parts and innervates the lower leg, foot and knee. The knee joint itself is innervated by the popliteal nerve, it is located behind it, and is divided into the tibial and peroneal branches.

The tibial nerve is located on the back of the leg, and the peroneal nerve is located in front. They provide sensory and motor innervation to the lower leg.

The blood supply to the knee joint is carried out using the popliteal arteries and veins, whose course follows the course of the nerve endings.

What are the risks of injury?

Depending on which component of the knee is damaged, injuries, diseases and pathologies are classified.

It can be:
dislocations,
fractures of the bones surrounding the joint,
inflammatory and dystrophic diseases,

The site is for informational purposes only. Do not self-medicate. If you notice any symptoms of illness, consult your doctor. The drugs presented on the site have contraindications; before use, read the instructions or consult a specialist.

How does the human knee work?

Joints perform an important function in the body, allowing movement and flexibility. The anatomy of the knee joint is the most complex, but it is its injuries that are most common. From this point of view, it is necessary to consider the structure of the knees in more detail, revealing all possible secrets.

It is better to start looking at the structure of the knees with the bones, which are the main component of any joint. Three bones are involved in the formation of the knee:

thigh (top);
tibia (bottom);
patella or kneecap.

The largest formation is the femur, more precisely, its two condyles. They are two rounded ends of the bone with smooth surfaces. There is space between them; there are ligaments in it, which will be discussed a little later.

Also, the tibia, or more precisely, the condyles, takes part in the structure of the knees. Their anatomy in humans is different from the thigh; they are flat, smooth and have a bulge in the middle. The smooth surfaces are also called plateaus; cartilaginous parts called menisci are located on them.

The last component is the patella, although in the knee joint it is considered the smallest, but in the body it is the largest sesamoid bone. There are such bones in the hands, they are additional levers and are located in the thickness of the tendon. The patella has two surfaces: one external, and the second internal, smoother, covered with cartilage. Also, the kneecap in humans has a base and a pole in the form of a narrowing at the bottom. Surrounded on all sides by ligaments, the cup moves easily.

Cartilaginous part

All articular surfaces are covered with cartilage, but between the condyles of the tibia and femur there are menisci. These are specific formations in the form of cartilage pads, in the joint one is internal and the other is external. During movements, they compress and shift; in addition, they eliminate the discrepancy between the articular surfaces in the joint.

But the anatomy of such a large and important joint as the human knee will be incomplete if we do not consider each meniscus separately. The external meniscus is a mobile formation, and therefore injuries are much less common. In contrast, the medial one is fixed by ligaments, its mobility is less, and the likelihood of injury increases.

Joint capsule

The knee capsule covers it on all sides, protects it and produces fluid that accumulates in the joint cavity. It is attached to the bone along the edge of the articular surface. Additional education capsules are bags they perform great value in practical activities. In total, a person has six bursae in the joint, which are found in everyone. There are additional ones that vary.

The most basic are:

In front of the patella there is a bag with the corresponding name.
There is also a corresponding bag under the patella.
There is also a bursa in front of the patella; it is located under the skin.
A bursa of muscles is distinguished, which is called semimembranosus.
The popliteus muscle also has its own bursa.

Ligamentous apparatus

In order for the joint to have greater stability, there are ligaments; they are attached to the bones and are internal and external. It’s better to start looking at the internal ligaments, which are located in the joint cavity. The anterior ligament originates from the inner surface of the lateral condyle of the femur. Crossing the joint diagonally, it is strengthened in the intercondylar fossa. This ligament allows you to stabilize the knee, control the degree of displacement of the tibia, and holds the lateral condyle.

The posterior cruciate ligament originates from the internal condyle of the femur, crosses the joint obliquely and is also attached to the intercondylar fossa. This ligament additionally strengthens the internal meniscus, allows you to stabilize the knee, and supports the lower leg when it is displaced.

There is also a whole system of external ligaments, one of them is the lateral, or collateral. With the help of these ligaments, the lower leg does not move to the side; if their anatomy is disrupted, the knee becomes unstable.

The front of the knee is covered by a ligament, which is a continuation of the quadriceps muscle. It covers the patella, further stabilizing the person’s knee. This ligament is attached to the tibial tuberosity. The patella acts as a lever during movement; if this ligament is damaged, straightening the leg becomes problematic. There are also ligaments at the back of the knee joint, for example, the oblique one, and next to it there is the curved one.

The free space of the knee is filled with folds, or outgrowths of the joint capsule. In front of the patella in humans there are wing-shaped folds that fill the free space between the condyles of the femur and the menisci. In the back of the knee, a person also has its own folds; they are smaller in size.

Synovial fluid

The joint, like any mechanism, has synovial fluid in its cavity for better gliding. Its composition looks like ghee, and the amount is approximately equal to a tablespoon. It is a nourishing composition for cartilage, including the patella. While walking, a person’s cartilage contracts and then, like a sponge, absorbs useful substances.

When the production of joint fluid is disrupted, a person develops a disease called synovitis. The amount of liquid increases sharply and can reach significant volumes. At the same time, the capsule becomes very tense, the joint constantly hurts.

The muscles move the joint, the largest of them in front is the quadriceps, which is responsible for extension. The posterior muscle group flexes the knee joint. In the knee, ligaments limit other movements, which is why the joint moves only in one plane.

Popliteal fossa

Behind the knee there is an important formation, which is limited by muscles and ligaments, it is called the popliteal fossa.
Important anatomical formations are concentrated in this area, for example, the popliteal artery. It is a continuation of the femoral artery, and vessels further extend from it to the lower leg. There are eight vessels in total that supply blood to the knee joint.

Also in this area there are large nerves, which are a continuation of the largest one - the sciatic one. There are also smaller branches that pass here and then go to the back of the lower leg. This place also contains lymphatic vessels; nodes are located next to them in this area, which can increase in size when infected.

The knee joint is the most complex joint in the human body, but it is the one that is often injured in everyday life. The knee contains in its cavity many important anatomical formations, when damaged, its function is disrupted, after which any person loses the ability to walk. Taking into account the structure, pathologies are diagnosed, and very often all kinds of damage, and this structure also helps to carry out surgical interventions.

Today, knee prostheses have been developed that allow a person to return to an active life. However, over time, the implant will have to be changed, because, no matter how good it is, it is not capable of self-renewal. This is why you should take care of your joints from a young age and avoid injuries.

Functioning and structure of the knee joint

The structure of the knee joint is very complex, it includes a large number of ligaments, nerve fibers, blood vessels and muscles. The knee joint is the largest joint in the human body. It takes on a lot of load and makes it possible to reproduce the most difficult actions: from ice skating to climbing trees.

The special structure of the human knee joint makes this joint vulnerable to injury and disease. Damage to the knee joint often causes disability and requires long-term treatment. The human knee is a collection of muscles, ligaments, nerves and blood vessels, bones and menisci. The action is similar to that of a ball joint. The lower leg can bend, straighten and rotate. Circular and rotational movements are made by the ligaments, which relax during the circular movement.

Joint-forming bones and ligaments

The knee joint is formed by two tubular bones. They are called femoral and tibial. The front of the knee is protected by a rounded bone called the patella.

The lower part of the joint is formed by two semicircular elevations of the femur - the condyles. The covering of the condyles consists of cartilaginous tissue. During movement, the condyles interact with a surface of the tibia called the tibial plateau.

This plateau is divided into two parts: medial (at the center of the body) and lateral. The kneecap moves along the patellofemoral recess formed by the femoral condyles.

How does the human knee work?

The thickness of the articular cartilage is 5-6 mm. Cartilage tissue covers the surface of the ends of the bones that make up the joint and the back of the kneecap. Cartilage has a smooth and shiny surface. This surface improves shock absorption and reduces friction between bones during movement.

The bones of the knee joint are fixed by connective tissue. To strengthen the joint capsule and prevent lateral movements, there are ligaments in the lateral parts: lateral and medial. Movement back and forth is controlled by the cruciate ligaments, which are located in the center of the knee joint. The tibia is held in place by the anterior cruciate ligament, which prevents the bone from sliding forward. To prevent the tibia from sliding backwards in relation to the femur, it is secured by the posterior cruciate ligament.

Menisci are cartilaginous formations

Between the ends of the bones there are menisci - cartilaginous formations. Menisci resemble cartilage tissue, but have a slightly different structure than the cartilaginous surface of the ends of the bones. The function of the menisci is to provide stability to the knee joint and distribute body weight evenly over the surface of the tibial plateau.

The structure of the menisci is more elastic than the articular surface of the bones.

The menisci act as pads that help distribute body weight evenly over the surface of the tibia. If the menisci were absent, then the plateau would experience excessive stress, and all the pressure would be placed on one point on the surface of the tibia. If the menisci are damaged, the cartilage begins to deform and the stability of the knee joint is impaired.

Structure of the knee meniscus

The thickness of the menisci in the central part is less than in the periphery. This structure forms a small depression on the surface of the tibial plateau, provides stability and allows the load to be distributed more evenly. The structure of the knee joint is formed by surfaces that cannot independently provide stability, as is the case in the hip or elbow joint. Therefore, ligaments play a huge role in strengthening the joint, without them it would be unstable.

Surrounding muscles

The work of the joint is provided by the muscles located around it. Muscles, in turn, are divided into three groups:

What muscles fix the human knee?

hip flexor muscles;
hip extension;
leading.

On the front of the thigh is the largest muscle in the human body - the quadriceps. The quadriceps muscle attaches to the kneecap and to the surface of the tibia. The knee muscle is formed from branches of the quadriceps muscle and is attached to the joint capsule. This muscle is responsible for the movements of the thigh and lower leg.

The sartorius muscle bends around the kneecap through the surface of the femur. It is then attached to the tibia. This muscle allows the lower leg to move back and forth.

The biarticular gracilis muscle originates at the pubic bone. In the form of a thin cord, it is attached to the tibia. This muscle, passing slightly to the side of the transverse axis, helps flex the joint.

The hamstrings help rotate the knee and flex the shin. There are semitendinosus muscles on the back of the thigh. Their work allows for rotational movements of the lower leg, extension movements of the thigh and lower leg. The gastrocnemius muscles begin at the condyles of the femur. These muscles are responsible for flexing the lower leg at the knee and ankle.

The function of the popliteus muscle is to pronate (rotate) the lower leg and flex it. This short and flat muscle is located on the back of the knee and begins at the lateral condyle.

Innervation and blood supply of the knee joint

The innervation pattern of the knee joint has many complex interweavings. Sensation is provided by the sciatic, tibial and peroneal nerves. The posterior part of the knee is innervated by the tibial nerve through articular branches. The anterior outer part of the patella is innervated by the peroneal nerve, which passes under the biceps muscle.

The nerves in the menisci run along the periphery of the cartilaginous body. The nerve plexuses penetrate the menisci with blood vessels. The nerve bundles of the menisci form pulpal and non-pulpate nerve fibers.

The nerve formations of the menisci are not very developed relative to other areas of human nerves. The knee joint, the structure of which is mechanically disturbed, is subject to dystrophic and necrobiotic changes.

Sclerosis occurs after damage to the nerves in the capsule.

The circulatory system nourishes all elements of the joint. A network of anastomoses connects all the veins of the knee. The periarticular tissue contains a venous network consisting of veins emerging from the joint capsule. The largest vessels are located on the back. The popliteal vein provides peripheral blood flow, and the popliteal artery returns blood flow to the heart.

The outflow of blood through the deep veins is due to the presence of valves in the veins. Lymphatic vessels are located along the blood vessels. Lymphatic drainage from the anterior internal part is carried out to the large inguinal lymph nodes.

The lymphatic vessels of the anterior part enter the popliteal fossa and connect to the lymphatic popliteal nodes. From the back, the lymphatic vessels also flow into the network of lymphatic vessels of the popliteal fossa.

Most common injuries

The most common knee injury is a torn ligament. The most common injury to the knee joint occurs in athletes (usually football players, skiers and wrestlers). This is a torn cruciate ligament. The ligaments are torn after strong blow

back of the knee. When the rupture is accompanied by fractures of the bony protrusions and fractures of the attachment points of the ligaments, treatment becomes very difficult. The posterior ligament can be damaged after a blow to the shin or when it is extended too sharply. The most severe form is the rupture of all ligaments, when the joint completely loses stability and its mobility deteriorates.

Ligament rupture is accompanied by severe pain. Blood begins to flow into the joint cavity. There are cases when the moment of injury itself is not noticeable, and symptoms of torn ligaments appear later when walking. The bones become too mobile, and “pushed-out drawer” syndrome occurs.

If the shin is twisted sharply, a meniscus fracture may occur. In case of injury or dislocation, it is important to limit the movement of the joint, apply an ice pack and contact a traumatologist. Such injuries are very dangerous and can result in disability.

When the bones of the knee joint break, surgery is required in most cases.

Does anyone know if draining fluid from their knee is very painful? They prescribed this procedure, I’m terribly afraid.

I remember they did this to my grandmother, they pumped fluid out of her knee. It helped, she immediately felt better, otherwise she was in a lot of pain and had joint pain.

How to determine whether a ligament has been torn or just sprained?

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The knee joint is one of the most complex joints in humans, combining the patella, femur and tibia into a single movable system. Its work is ensured by cartilage, ligaments, muscles and tendons.

The structure of the human knee joint explains the cause of emerging pathologies and helps to understand the etiology and course of inflammatory and degenerative diseases. Even small deviations from the norm in any element of the joint can cause pain and limited mobility.

The structure of the knee joint is significantly different from other joints. This is explained by its functional features.

It is the knee joint that redistributes a person’s weight to the ankle and foot, and compensates for jumps and falls.

The knee joint bears a significant load throughout a person’s life: constant flexion and extension when walking up stairs, during squats, and the like.

Bones

The knee joint connects the femur to the tibia. In front is the so-called patella. This is a bone small size, it has a round shape.

The bottom of the femur ends in two spherical protuberances. They are called condyles and are covered with articular cartilage. They form the surface of the joint on the femur. In this case, the femoral condyles form a groove along which the patella moves.

The tibia has a flat surface. It is also covered with cartilaginous formations, which have a more rigid structure.

Articular cartilage is dense, elastic, smooth. Its thickness at the knee varies from 5 to 6 mm. Main functions:

reduction of friction when moving;
compensation of loads during jumps and falls.

Menisci

In a primitive view, the knee joint looks like a ball (femoral condyle) lying on flat surface(tibia). Stability of the joint is achieved through the menisci.

The meniscus is a wedge-shaped formation of cartilaginous tissue. They are thicker at the edges and thinner in the center. The structure of the fabric is fibrous.

The menisci are attached to all components of the knee using reinforced ligaments so that the edges of the menisci are rigidly fixed, and the meniscus itself can move. Due to this, rotational movement of the limb is achieved.

The main function of the meniscus is stable operation of the joint and rational distribution of body weight.

Ligaments

Ligaments are dense connective tissue that fixes the movement of bones relative to each other. They come from the condyles of the femur, and, accordingly, crossing each other, are attached to the front and back of the tibia. This structure prevents displacement of the components of the joint.

Tendons are not ligaments or a type of ligament, they connect muscles to bones.

Injuries

Due to its structural features and constant physical activity, the knee joint is easily injured. The risk group is headed by athletes.

Usually the cartilage is damaged or the ligaments are torn. Let's consider several typical traumatic consequences caused by the structural features of the knee joint.

Meniscus tear

A meniscus tear can occur due to:

careless extension of the joint;
primary or secondary knee injury;
degenerative changes.

Secondary injury leads to chronic consequences - the menisci will be destroyed at any physical activity. The easiest place to break is the one that has already been broken, even if it has healed successfully.

Cartilage, meniscus and the entire joint degenerate due to:

gout;
intoxication;
metabolic disorders;
excess body weight;
insufficient physical activity;
chronic or congenital injury;
excessive strength exercises;
standing work.

Combination of trauma

A combined injury is possible, in which the cartilage is exposed to traumatic effects along with the muscles, fat body, ligaments - all components of the joint. Due to the displacement of the torn part, the ligaments can be cut and the cartilage breaks, and chondromalacia develops.

Symptoms

Diagnosing the damage is difficult due to the uniqueness of the symptoms. The main “difficulty” in diagnosis lies in the symptoms of reactive inflammation. Self-medication is unacceptable.

Severe local pain at the site of injury, inability to flex and extend, swelling, bruise or tear, presence of effusion or hemarthrosis - characteristic features combined injury. Such symptoms indicate that the meniscus is pinched or crushed, but it has not separated from the capsule. If you start treatment at this stage, you can completely get rid of the injury without any consequences. But in any case, you need to be careful, since re-tear of the meniscus is more than likely with the next injury or excessive load.

Two weeks after the injury, if no treatment is taken, the following symptoms occur:

joint blocking;
severe local pain;
capsule infiltration;
effusion.

Diagnostics

To make a final diagnosis, certain tests are performed, of which there are quite a few:

extension (Land, Baikov, Roche);
compression;
mediolateral;
rotational (Steiman-Bragard).

To determine how damaged the knee joint is, a joint block is performed on the cartilage, muscles or ligaments.

The main symptom that causes the doctor to suspect a meniscus tear is local pain, which only intensifies when the leg moves inward. Related:

swelling;
swelling;
click or roll;
symptom of blockade;
infiltration.

An X-ray examination is also carried out. On the x-ray you can see that the sections of the joint space have narrowed, as in deforming arthrosis. In such cases, treatment is a paraclinical method.

It is impossible to establish such a diagnosis, especially when not only the meniscus is damaged in combination, but also cartilage, ligaments, muscles, joint capsule and other elements of the system, solely on one basis - several studies are carried out and only then a verdict is made and treatment is prescribed.

Although both menisci are damaged at the same time extremely rarely, even this occurs due to the pathology of the development of the musculoskeletal system. The menisci are too mobile, which is why they are easily damaged. It is more difficult to diagnose such a rare pathology, since the internal meniscus is usually injured.

There are a number of other injuries that are diagnosed using joint blockade, but they are often, although accompanied by effusions, short-lived, easy to get rid of and no consequences remain. Such damage includes:

infringement of the hypertrophied pterygoid fold;
chondromalacia;
Hoffa's disease;
bruises;
Koenig's disease;
damage to the capsular-ligamentous apparatus;
chondromatosis.

On average, the statistics of diagnostic errors is 10%. That is why you should never self-medicate or self-diagnose.

Ligament injuries

Instability of the knee joint due to torn ligaments occurs when the shin is bent or rotated inward, and the impact falls on the back of the joint. Usually there is a rupture of not one, but three ligaments at once, which is accompanied by a fracture of the bone plates or intermuscular eminence where the ligaments are attached. This greatly complicates treatment.

At risk are football players, skiers, and wrestlers.

Symptoms

When the cruciate ligaments are injured, the following symptoms occur:

acute pain;
edema;
clicks when bending;
joint instability and hypermobility;
syndrome " drawer».

In older injuries, drawer syndrome may be alleviated by tearing of the fatty tissue that partially stabilizes the joint. Then the doctor conducts X-ray examination, after which the diagnosis is accurately determined.

First aid

The goal is to immobilize the limb to prevent the injury from worsening. This may require a tire or any other strong material at hand: boards, strong branches, plastic panels. The area must also be numbed. The victim is immediately taken to the hospital.

Diagnostics

Since a ligament rupture cannot be determined by any one symptom, several tests and studies are performed during diagnosis.

"Drawer"

The shin is too far forward or backward, depending on which ligament was torn. Ligament rupture can be determined by anterior subluxation of the tibia relative to the thigh.

Lachman test

This test is performed in a lying position on your back. The joint is bent at an angle of 160°. The outer part of the thigh is held while the other hand, which is placed behind the back of the proximal part of the leg, is pulled forward, carefully and gently. The result is the amount of forward displacement of the tibia, as well as a change in the configuration of the knee joint.

Slip test

This test is also performed while lying on your back. The surgeon holds the leg by the foot, placing the limb in a position of internal rotation, and with the other hand acts on the upper third of the back of the lower leg. The joint slowly bends. The result is the illusion of moving the joint back into place.

other methods

Additional diagnostic methods:

palpation;
inspection;
anamnesis collection.

In some cases, additional measures are indicated: tomography, injection of contrast fluid into the joint capsule, MRI, arthroscopy. Arthroscopy allows you to examine the joint cavity from the inside using a probe.

Treatment

Blood is removed from the joint and Novocaine is injected. After making sure that only the ligaments are damaged, a plaster cast is applied. A plaster cast is applied to the leg, which is slightly bent at the knee. Plaster is used only if the cartilage, muscles and menisci are intact.

You will have to wear a cast for about a month. Then the rehabilitation process begins. Muscles are restored through massage, physiotherapeutic procedures, and physical therapy.

In case of a fracture with bone displacement, urgent surgery is required. The bones are aligned and the fracture site is fixed.

In the absence of complications, cruciate ligaments are not restored immediately after injury. Ligament restoration should also be postponed if the joint is loose. In this case, the operation is performed only after a month and a half.

The ligaments are not sutured, but plastic reconstruction is performed using tissue from the patient’s patella. In rare cases, insert artificial dentures, but they are short-lived and after a while you will have to repeat the operation.

The methodology for performing such operations can be:

open;
half open;
endoscopic.

When open surgical intervention an incision is made throughout the joint cavity.

If it is possible to use a semi-open surgical technique, the incision is minimal.

Endoscopy is minimally traumatic, joint mobility is restored within a few days.

Regardless of the type of operation, full weight bearing on the leg is possible after at least a year.

Finally

The knee joint is the most vulnerable joint in the human body. It is extremely easy to injure it: athletes, overweight or elderly people, as well as simply unfortunate people who are unlucky enough to fall and hit their knee are at risk. In no case should you neglect such an injury, as you may forever lose the ability to walk normally. Self-medication or treatment with folk remedies is also strictly prohibited.

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