Patellar dislocation is its vertical, horizontal or torsional displacement from the intercondylar cavity of the tibia (codes M21.0 and M22.1 according to the ICD-10 classification). With such an injury, acute pain immediately occurs, the mobility of the knee is blocked, the support function of the leg is partially or completely lost. Since the symptoms are similar to those of a knee fracture, an accurate diagnosis is made by a physician using x-rays. After this, the patella is returned to its place and further treatment is prescribed - complete immobilization of the limb for a period of three weeks to one and a half months or surgery. Only in 25% of cases such dislocations occur as a result of injury, the rest are due to weak ligaments and muscles, various defects of the knee or femur joint.
Knee and patella anatomy
One of the main organs that ensures upright walking, running and jumping is the knee joint. It has a complex structure and consists of:
- Tibia, fibula and femur, patella (patella).
- Two intra-articular and five extra-articular ligaments.
- Five synovial bags.
- Three muscle groups (anterior, posterior and internal).
The patella is formed from cartilage tissue during human development (by about seven years). It has the shape of a triangular or tetrahedral pyramid with rounded corners. Its inner part (longitudinal ridge covered with hyaline cartilage) is located in the intercondylar cavity of the femur. The flat side faces the outside of the joint, and is attached from below by its own ligament to the tibia, and from above to the tendons of the quadriceps muscle of the thigh. The patella provides protection from damage and stabilizes the position of parts of the knee joint, and when it is extended, it effectively transfers the force of the thigh muscles to the lower leg.
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Kinds
Patellar injuries are divided into:
- Due to the occurrence:
- external traumatic impact;
- congenital or acquired, as a result of the disease, pathological changes in the knee joint.
- In the direction of displacement:
- lateral;
- rotary;
- vertical.
- By the degree of damage:
- light and medium - a slight change in the position of the patella without rupture of the ligaments;
- acute - primary dislocation, which is accompanied by complete displacement of the patella and destruction of the surrounding structures: cartilage, ligaments;
- habitual - repeated many times due to pathological changes in the environment, dislocation or subluxation.
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The reasons
Playing football, weightlifting, jumping, contact martial arts and other sports, which are associated with sharp lunges, falls, blows to the knee and constant loads on the knee joint, often lead to traumatic dislocations of the patella and pathologies such as lateroposition (permanent displacement to outer side) and osteochondropathy (degenerative changes in cartilage tissue).
Dislocations can occur due to abnormal development or underdevelopment of joint components. Old knee injuries or degenerative changes in its structures due to illness or surgery can also cause injury.
Symptoms
In primary cases, intolerable pain always immediately arises, there is a feeling of the knee joint flying out and its mobility is blocked. In severe injury, complete rupture of the ligaments and destruction of cartilage can occur.
With a dislocation, the patella completely leaves its bed and shifts:
- To the right or to the left with lateral dislocation - a depression is visually visible in the middle of the knee, and an abnormal tubercle is visible from the side.
- Around the vertical axis in torsional dislocation - the middle part of the joint is unnaturally enlarged.
- Up or down with vertical dislocation - respectively, the patella occupies a position above or below normal.
Usually, the kneecap takes up a normal position on its own when the leg is extended. The severity of pain decreases, edema appears. Joint mobility is not restored and hemorrhage into its cavity is possible. Depending on the type of injury, pain is localized in the region of the medial retinaculum, lateral femoral condyle, or the middle edge of the patella.
In order not to confuse a dislocation with a fracture of the joint, the diagnosis must be specified using an X-ray.
With subluxation, the pain syndrome is mild. The mobility of the knee is almost unlimited, the dislocation of the patella is slightly different from normal. When bending or unbending, it appears: crunching, sensation of falling leg and joint instability.
Diagnostics
With pronounced symptoms of mild injury, the patella spontaneously falls into place or the doctor does this during the initial examination. To clarify possible damage, X-rays of the joint are taken in two or three planes.
In case of insufficient information content of the roentgenogram, computed or magnetic resonance imaging is performed. When blood is suspected in the patella cavity, then a puncture is used. If it is necessary to obtain detailed information about the condition of the knee elements, arthroscopy is used.
If pathological changes of a non-traumatic nature became the cause of the dislocation, then measures are taken to establish the disease that caused them, and its pathogenesis is thoroughly studied.
First aid
First of all, the pain syndrome should be removed - a cold compress should be applied to the knee and an analgesic should be given to the victim. Then it is necessary to ensure the immobility of the joint using any materials at hand, a bandage made of elastic bandage, a special bandage or splint. You should not unbend the bent leg or correct the dislocation. To avoid complications and the appearance of the habitual dislocation, it is necessary to deliver the patient to the emergency room as quickly as possible.
Which doctor to contact
Depending on the type and degree of damage, dislocation of the patella is engaged in:
- Traumatologist - primary diagnosis and treatment.
- Surgeon - performing operations.
- Orthopedist or vertebrologist - rehabilitation and relapse prevention.
Treatment
As a rule, the reduction of acute dislocations by a medical specialist is quick and relatively painless. Then a control X-ray is taken and, if no additional damage is visible, the joint is immobilized with a plaster cast. In case of untimely seeking medical help (more than three weeks after injury) or in difficult cases (habitual dislocation, complete rupture of ligaments, destruction of cartilage), an open operation or arthroscopy is performed.
Rehabilitation, terms of recovery and wearing a plaster cast
The duration and types of post-traumatic events completely depend on the severity of the injury and the methods of treatment. The immobilization period can range from three weeks to six months. One of the initially prescribed procedures is a therapeutic massage, which sometimes begins to be gently applied to the muscles of the thigh and lower leg immediately after the elimination of pain and edema. To restore muscle tone and knee mobility after plaster removal, in addition to massage, they begin to develop joints, first with the help of a doctor, and then independently with the help of special exercises.
Various physiotherapeutic procedures have a beneficial effect on the processes of restoring the elasticity of the ligaments and regenerating muscles: UHF, electrophoresis, laser exposure, applications of esokerite.
Physiotherapy (exercise therapy) is prescribed 2-3 weeks after the removal of the plaster. At first, with minimal stress and a small range of motion. In order to avoid repeated patella popping out during this period, it is necessary to wear a fixation bandage. Then, within 2-3 months, the load and range of motion are gradually increased. By the end of the period, the ability to walk normally with a support bandage is restored. In order not to dislocate the kneecap again when performing physical exercises that do not exclude falls, it is necessary to use a knee pad. Full recovery of exercise tolerance and the ability to run and jump is achieved by intensive exercises in medical gymnastics for 6-12 months.
Consequences and collateral damage
Dislocation of the patella can be complicated by serious damage to the surrounding ligaments, cartilage, menisci. Late visits to a doctor or improper reduction can cause habitual dislocation and gradual loss of knee performance. In difficult cases, especially after surgery, inflammation of the tendons of the patella or the lining of the articular cavity may occur.
