The patella (Latin patella) is a bone that forms part of the knee joint. The patella is located within the tendon of the quadriceps muscle of the thigh. The most important functions of the kneecap are protection against injuries and participation in extension movements of the knee joint. The superficial position of the kneecap and high loads during movement mean that it is not difficult to injure within this bone. Overloads, dislocations and fractures of the kneecap are particularly common among people who practice sports. Find out how the kneecap is built, what functions does the kneecap perform and what are the most common diseases of the kneecap.
Rzepkabelongs to a unique group of bones in our body called naviculars. Trzeszcze are small bones located within the joints. Tissues are formed as a result of ossification of fragments of muscle tendons. The greatest number of tiny sesamic organisms is located in the hands and feet. The kneecap - the largest navicular bone in the human body - is located in the knee joint, being its most forward part.
Rzepka - construction site
When discussing the structure of the kneecap, it is worth remembering the basic anatomy of the knee joint. The main bones that connect at the knee are the femur and the tibia. The kneecap is an additional bone in the knee, which primarily performs protective and mechanical functions. The patella has a connection with both the tibia and the femur, although they are of a different type.
The patella connects to the tibia via the patella ligament. On the other hand, the connection of the patella with the femur is direct - the articular surfaces of the patella are adjacent to the distal end of the femur.
The front part of the patella is a smooth surface, easily felt under the skin in the knee area. In the posterior part of the patella there are two articular surfaces - lateral and medial. These surfaces meet the lower condyles of the femur. This creates the patellofemoral joint, which is one of the elements of the knee joint.
The shape of the kneecap slightly resembles a triangle with rounded apexes, with the base pointing upwards. On the upper side, the kneecap is connected to the tendon of the quadriceps muscle of the thigh. The kneecap plays a huge role in the biomechanics of the quadriceps muscle and, consequently, of the entire knee joint.
On the lower side, the kneecap has the so-called the tip to which the patella ligament attaches.The patellar ligament connects to the tibia, or more precisely to a small protrusion in its upper part, called the tibial tuberosity.
On both sides of the kneecap there are additional, fibrous structures called the patella straps. The patella straps connect to the tibia. Together with the tendon of the quadriceps muscle and the patellar ligament, they contribute to its stabilization. As a result, in a properly functioning knee, the patella moves only in a strictly defined plane and is protected against excessive movement.
In the area of the kneecap there are numerous structures made of soft tissues, which also belong to the knee joint. The membranes that form the joint capsule attach to the kneecap articular surfaces. The synovial membrane of the joint capsule creates numerous protrusions, called synovial bursae. There are supra-, sub- and pre-patellar bursae in the area of the kneecap. Inside the synovial bursae, the production of synovial fluid, i.e. a substance filling the joint and reducing friction within it, takes place.
On the posterior-lower side of the patella there is the so-called Subpatellar Fat Body, also called Hoffy Fat Body. It is a piece of adipose tissue that allows partial shock absorption and filling the free spaces in the knee joint.
The microscopic image of the patella shows various types of tissues. The basis is, of course, bone tissue, which appears in the kneecap around the age of four. The process of complete ossification of the patella lasts up to several years (on average, 3-6 years of age). Previously, its main component was cartilage.
In a properly developed kneecap, there is no complete loss of cartilage - in a mature knee, the articular surfaces of the patella are covered with a thick layer. Cartilage tissue has considerable flexibility, which allows it to carry high joint loads.
There is also a small hole in the kneecap through which blood vessels carry blood to the inside of the bone. In this way, the kneecap receives oxygen and nutrients necessary for its proper functioning and regeneration.
It is worth knowing, however, that the vascularization affects only the bony part of the patella. Cartilage is much less nourished - only through the synovial fluid. For this reason, it is usually impossible to fully repair damaged cartilage in the event of its injury or degeneration.
Rzepka - functions
The primary function of the kneecap is to protect the knee joint from injuries. The kneecap, being the most forward part of the joint, absorbs a large part of the energy at the time of injury. Thus, structures are protectedknees more back. Unfortunately, the kneecap itself is therefore more susceptible to damage.
The kneecap's protective function is also based on cushioning and dispersing the stresses on the femur, especially during movements that put stress on the knees - such as running or jumping. The kneecap also plays a huge role in the biomechanics of the knee joint.
The functioning of the kneecap in the movement apparatus mainly concerns its connection with the quadriceps muscle of the thigh. It is a very large muscle, composed of - as its name suggests - four parts. Each of them connects with the patella in the final section, ultimately forming a common part - the patellar ligament.
The kneecap carries all the strength of the huge muscular system, the main task of which is to extend the knee joint. During quadriceps contraction, the patella rises upwards, thereby increasing the angle of action on the tibia. The result is a knee extension with less effort.
Knowledge of the anatomy and functioning of the kneecap is also useful in medical practice. Many of the relatively simple tests related to the kneecap can provide valuable information about the locomotor system and nervous system. A good example is the knee reflex test where the examiner hits the patellar ligament with a hammer. The correct reflex is to gently extend the knee. Both an excessive and a weakened reflex may indicate a pathology within the nervous system.
Another example is the patella ballot test performed during an orthopedic examination. A positive result of this test indicates the presence of excess fluid in the knee joint - most often blood or inflammatory exudate.
Turnip - diseases
Patellar diseases most often arise as a result of excessive strain on the knee joint. Their common cause is inappropriate physical activity. If the structures around the knee joint - muscles, ligaments and tendons are not adapted to high loads (jumping, running, deep squats), then a significant part of the energy is transferred incorrectly. In this way, the risk of knee injuries, including damage to the kneecap, increases.
It is also worth remembering that overweight is an important risk factor for overloading the knee joints. Apart from traumatic etiology, patellar diseases can be caused by congenital defects as well as metabolic disorders.
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dislocation of the patella
Patellar dislocation is the dislocation of the patella outside the correct location within the knee joint. In the event of dislocation, the kneecap is completely dislocated, ain case of subluxation - partial. Patellar dislocation is especially common in children, with trauma being the most common cause.
A dislocated kneecap in some cases returns to its place by itself, but usually dislocation requires adjustment and subsequent immobilization. Patellar dislocation may be associated with damage to its stabilizing apparatus, which increases the susceptibility to subsequent dislocations. We are then talking about the so-called habitual dislocation of the kneecap.
An additional factor that increases the risk of dislocation recurrence is the inborn tendency associated with excessive mobility of joint structures. Repeated dislocations of the patella, combined with damage to the ligamentous apparatus, may be an indication for surgical treatment.
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fracture of the kneecap
A fracture of the kneecap is most often the result of a direct injury - usually a fall and hitting the kneecap on a hard surface. Patellar fractures, in contrast to dislocations, are more common in adults. In children, the patella bone tissue is not fully mature, which makes it more flexible.
The choice of a method of treating a patella fracture depends on the severity of the injury and the presence of complications. Simple, non-displaced fractures only require immobilization in a plaster cast. Fractures with dislocation or accompanying damage to the structures of the knee joint may require surgery.
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Jumper's knee
The knee of a jumper is a common problem among patients practicing sports related to excessive stress on the knees - athletics, volleyball or basketball. The main symptom of this condition is pain and swelling in the front part of the knee.
The cause of the jumper's knee is inflammation of the patellar ligament, which is the structure that connects the patella to the tibia. The knee of a jumper is usually treated conservatively, using appropriately selected methods of rehabilitation and physical therapy. In extreme cases, such as a complete rupture of the patellar ligament, surgical treatment may be necessary.
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patella chondromalacia
Chondromalacia of the patella can be graphically described as its softening. This process mainly affects the patellar cartilage - bone tissue is involved only in the most advanced forms of the disease. The pathology mainly occurs at the junction of the patella with the femur, which is why this condition is also called the patellofemoral conflict.
Patellar chondromalacia occurs most often in young people. There are many causes of this condition: past injuries and inflammation of the knee, congenital predisposition, andchronic overload of the patella leading to degenerative changes.
In the treatment of patellar chondromalacia, both pharmacological therapy (including anti-inflammatory drugs), physiotherapy and surgical procedures are used.
- Sprains, sprains, fractures - how to help an injured person
- Knee Injuries: Symptoms and Diagnosis
- Inflammation of the patellofemoral joint (kinoman's knee) - causes, symptoms and treatment
- Degeneration of the knee joints (gonarthrosis). Knee degeneration causes and treatment