Dislocation: causes, symptoms, diagnosis, treatment

Dislocation (luxatio) is a persistent displacement of the articular ends of articulating bones beyond their physiological mobility with disruption of joint function.

The name of the dislocation is given by the damaged joint or the underlying segment is considered dislocated (except for the clavicle and vertebrae). Example: dislocation of the elbow joint or dislocation of the forearm, but not dislocation of the elbow joint.

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Epidemiology

Traumatic dislocations are the most common type, accounting for 2-4% of all skeletal injuries and 80-90% of all other dislocations. They occur in all age groups, but mainly in men aged 20-50: they account for 60-75% of injuries.

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What causes a dislocation?

The most common cause of dislocations are indirect mechanism injuries - violent movements that exceed the functional capabilities of the joints. In this case, as a rule, the joint capsule is torn, partially the ligamentous apparatus, and the surrounding soft tissues are injured.

Symptoms of dislocation

Among the joints of the extremities, the shoulder joint is most susceptible to dislocation. Damage to arteries and nerves during dislocations is uncommon, but the risk of their occurrence exists (for example, with dislocations in the knee, elbow joints or hip joint dislocation), especially with delayed reduction of the dislocation.

Traumatic dislocation is accompanied by an extensive rupture of the joint capsule, rupture or tear of tendons, less often by rupture or compression of blood vessels and nerves. Clinical manifestations of injury are typical: pain; swelling, bruising, dysfunction of the limb. Characteristic features of this type of injury are: change in the shape of the joint, its contours are smoothed out; a depression is palpated at the site of one of the articular ends; an attempt at passive movements in the joint causes a sharp increase in pain, a springy resistance is felt.

In clinical practice, the most common are hip dislocations, which are congenital, shoulder dislocations, mostly habitual, and subluxation of the head of the radial bone in children when the child's arm is suddenly pulled by an adult who is leading him (Chassaignac dislocation).

Symptoms of dislocation include pain, swelling, joint deformity, and inability to move. Diagnosis is confirmed by radiography. Treatment usually consists of closed reduction as soon as possible; this requires sedation and analgesia and sometimes general anesthesia. The condition of the vessels and nerves is assessed before and after reduction. If closed reduction is unsuccessful, open surgery is indicated.

Classification

Dislocation is classified as follows:

1. By origin, dislocation is divided into: acute traumatic (the first 3 dislocations in the same joint, documented by radiographs); habitual traumatic dislocation after three acute traumatic ones; congenital, as a consequence of birth trauma; pathological dislocation in diseases and oncological processes in the joint area.
2. By volume, dislocation is divided into: complete, when a total discrepancy in the position of the articular surfaces is formed; partial (subluxation), when contact is limited, but remains.
3. By localization: the lower segment of the limb is indicated (for example, in case of dislocation in the shoulder joint - shoulder dislocation, in the elbow joint - forearm dislocation, in the hip joint - hip dislocation, etc. Only dislocation of the vertebrae is designated by the overlying vertebra (for example, in case of dislocation in the area of the first cervical vertebra, the diagnosis is defined as a dislocation of the head; in case of dislocation between the 12th thoracic and 1st lumbar vertebrae - dislocation of the 12th thoracic vertebra).
4. Depending on the duration from the moment of injury, dislocations are divided into: fresh (up to 3 days); stale (up to 3-4 weeks); old (more than a month).
5. Based on damage to the skin, dislocations are divided into closed and open.

The so-called fracture-dislocations are especially distinguished, when there is a bone fracture in the area of the intra-articular capsule and a dislocation (or subluxation of the head of the bone). Most often, this dislocation is noted in the shoulder, ankle, elbow, and wrist joints. A fracture-dislocation in the hip joint can be of two types: simple, when there is a fracture of the femoral neck and its dislocation; and a central fracture-dislocation, when there is a fracture of the acetabulum, through which the head of the femur (there may or may not be a fracture of the femur) is wedged into the pelvic cavity.

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Certain types of dislocations

Dislocation of the shoulder joint

Shoulder dislocation is anterior in 95% of patients. The typical mechanism is abduction and external rotation of the shoulder. Damage to the axillary nerve or avulsion of the greater tubercle is not uncommon, especially in patients over 45 years of age. The acromial process protrudes during shoulder dislocation, the head of the humerus is displaced forward and downward and is not palpated in its usual place. The sensitivity of the axillary nerve, which passes along the lateral edge of the deltoid muscle, is checked. Treatment usually consists of closed reduction with sedation, but with preservation of consciousness. The Mukhin-Mott closed reduction method is used most often. After reduction, the joint is immediately immobilized with a bandage or sling.

Rarely, a posterior dislocation is observed - usually an undiagnosed injury, or a lower one (luxatio erecta). The latter is often accompanied by damage to the brachial plexus and brachial artery.

When the shoulder is dislocated, Pagenstecher syndrome may occur - subluxation of the head of the humerus upward and inward with simultaneous rupture of the biceps tendon.

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Elbow dislocations

A common mechanism is a fall on an extended and abducted arm. Elbow dislocations are common, with the posterior type being more typical. Associated injuries may include fractures, neuritis of the ulnar and median nerves, and possible injury to the brachial artery. The limb is usually flexed at the joint at an angle of about 45°, the olecranon process protrudes strongly and is palpated behind the humeral condyle and above the line connecting the humeral epicondyles; however, determining the relationship of these anatomical structures is sometimes difficult due to severe edema. The dislocation is usually reduced by prolonged gentle traction after sedation and analgesia.

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Subluxation of the radial head

In adults, the head of the radius is wider than its neck, which prevents the radial head from penetrating the fibers of the annular ligament that tightly encircle the neck. However, in toddlers (about 2-3 years old), the head of the radius is not wider than its neck and can easily penetrate the fibers of the ligament, causing a subluxation. This can happen when a child falls forward with a sharp pull on an outstretched arm, but most parents do not take this into account. Symptoms may include pain and tenderness on palpation; however, in most cases, children are unable to clearly convey their complaints and simply protect their arm from moving the elbow joint (pseudoparalysis). Plain radiographs are normal; some experts believe that they should not be performed unless an alternative diagnosis is suspected. Reduction can be either diagnostic or therapeutic. The elbow is fully extended and supinated, then flexed, usually without sedation or analgesia. In children, joint mobility is restored in approximately 20 minutes. Immobilization is not necessary.

Dislocations of the proximal interphalangeal joint

Typical dislocation. Dorsal displacement of the middle phalanx occurs more often than ventral, usually with hyperextension, sometimes with displacement of intra-articular structures. Palmar dislocations may be accompanied by rupture of the central portion of the extensor tendon with the formation of a boutonniere-type deformity. Such a deformity is common with dislocation of the proximal interphalangeal joint. In case of visible separation of the injured finger from the others, a lateral radiograph should be taken.

In most cases, closed reduction is performed under conduction anesthesia. In case of dorsal dislocation, axial traction and palmar force are used, in case of palmar dislocation, dorsal force is used. In case of dorsal dislocation, splinting is performed with flexion at 15° for 3 weeks. After palmar dislocations, splinting is performed in the extension position for 1-2 weeks. In some cases, open reduction may be required for dorsal dislocations.

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Hip dislocations

Most cases are posterior dislocations, which occur with a significant posterior force on the knee while the hip and knee joints are in flexion (e.g., hitting a car dashboard). Complications may include arterial injury (especially with anterior dislocations) followed by avascular necrosis of the femoral head and sciatic nerve injury. Treatment consists of rapid reduction followed by bed rest and joint immobilization.

Congenital hip dislocation is characterized by specific symptoms: Allis symptom - when the child is lying on his back with his legs bent at the knees, a difference in the length of the limb is revealed; Malgenya symptom - in a position on the healthy side, the patient should bend and bring the dislocated hip to the body, then make rotational movements with it, while the dislocated head of the femur is easily palpated; Marx ("slipping") symptom - when trying to abduct the bent leg of a child lying on his back, at one of the moments of abduction the head with a characteristic click is reset into the socket, when the leg is brought together it is dislocated again; Trendelenburg symptom - when leaning on the sore leg, the pelvis on the healthy side drops, the gluteal fold shifts upward. In a patient lying on his back or on X-rays, the Briant triangle can be determined - a line is drawn from the anterior superior iliac spine to the back, a line is drawn perpendicular to it from the greater trochanter upward (Briant's line), the hypotenuse of the triangle is the line from the superior spine to the greater trochanter - in case of congenital hip dislocation or other pathology of the head and neck of the femur, the triangle becomes not isosceles, but with a shortened Briant line.

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Knee joint dislocations (femorotibial)

Most anterior dislocations result from hyperextension; most posterior dislocations result from direct posterior force on the proximal metaphysis of a slightly flexed tibia. Many dislocations spontaneously reduce before seeking medical attention, which may cause significant instability later. Injury to the popliteal artery is common and should be considered even in the absence of limb ischemia. Angiography is indicated in all patients with severely unstable knee dislocations. Treatment consists of immediate reduction and surgical repair.

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Lateral dislocation of the patella

A common mechanism is contraction of the quadriceps muscle with flexion and external rotation of the tibia. Most patients have a history of patellofemoral pathology. Many dislocations are reduced spontaneously before seeking medical attention. Treatment is by reduction; the femur is moderately flexed, the patella is gently displaced to the side with extension of the knee joint. After reduction, a cylindrical plaster cast is applied to the tibia, and if indicated, surgical treatment is performed.

Diagnostics

The diagnosis of dislocation is specified and documented by X-ray, preferably in two projections, but in the absence of conditions, one is enough. X-rays are given to the victim or stored in the hospital archive, without the right to destroy them, they must be issued on first request. This is necessary for documentary confirmation of the diagnosis of habitual dislocation (more than three times in one joint), in which there are indications for surgical treatment and grounds for exemption from military service, and sometimes for determining disability. Pathological dislocations are formed with degenerative diseases of the joints: tuberculosis, arthropathies of various genesis, arthrosis, arthritis, mainly when the joint capsule is changed.

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Inspection and physical examination

The joint is deformed. Palpation reveals changes in the external landmarks of the joint and pain. There are no active movements in the joint. An attempt to perform passive movements causes sharp pain. A symptom of springy resistance is determined. The latter consists in the fact that the doctor performing passive movements feels elastic resistance to movement, and when the effort stops, the limb segment returns to its previous position.

If a dislocation is suspected, it is necessary to check the pulsation of the arteries, skin sensitivity and motor function of the distal part of the limb, since damage to the neurovascular bundle is possible.

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Laboratory and instrumental studies

When diagnosing dislocations, it is necessary to conduct an X-ray examination, without which it is impossible to establish the presence of concomitant fractures without displacement and bone cracks. Otherwise, when attempting to reduce the segment, a fracture and displacement of fragments may occur.

Treatment of dislocation

First aid

Treatment of fresh dislocations is an emergency measure; it should be started immediately after diagnosis. Assistance begins with the introduction of pain-relieving narcotics.

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Conservative treatment

After anesthesia, the dislocated segment of the limb is repositioned.

The most common is a shoulder dislocation. During examination, in addition to the above symptoms, a soft tissue depression is detected in the upper third of the shoulder, under the acromion. The patient tries to hold the injured arm with the healthy one, tilting the body toward the injury.

First aid consists of applying a sling or Desault bandage and administering analgesics. The injured are subject to urgent delivery to the hospital, where the doctor, depending on the nature of the injury and the patient's condition, selects a specific method of reduction.

Usually, when reducing a dislocation, the doctor needs 1-2 assistants. Most often, shoulder dislocation is eliminated using the Kocher, Mota-Mukhina, and Hippocrates methods. When reducing a shoulder dislocation using the Kocher method, four consecutive stages are distinguished. Stage 1: the surgeon grasps the elbow joint area from behind with one hand and the forearm in the wrist area with the other hand. Bending the arm at an angle of 90° at the elbow joint, he carries out traction along the axis of the shoulder of the injured limb and brings the shoulder to the body. The doctor's assistant must fix the victim's body and perform countertraction. Stage II: without stopping traction along the axis, the doctor turns the shoulder outward so that the inner surface of the forearm coincides with the frontal surface of the body. Stage III: Without releasing traction, the surgeon slowly brings the elbow toward the midline of the body while simultaneously rotating the arm outward, which often corrects the dislocation.

If the reduction does not occur, proceed to stage IV: without weakening the traction, the forearm and shoulder are quickly turned inward and sharply thrown back to the healthy side so that the hand ends up on the healthy shoulder joint.

The reduction of the dislocation is accompanied by a click, and movements in the shoulder joint become possible. With the patient lying down, before coming out of anesthesia, the doctor and assistants apply a soft Desault bandage with a small roller in the axillary area.

When reducing a shoulder dislocation using the Mota-Mukhina method, the injured shoulder is covered with a towel or folded sheet so that the ends are directed toward the healthy side. One assistant pulls the ends of the towel toward the healthy shoulder, and the second bends the arm at the elbow at a right angle and holds the forearm with both hands.

The traction in opposite directions is carried out gradually, avoiding jolts. The doctor palpates the displaced head of the humerus in the armpit and fixes it with his fingers. At the doctor's command, the assistant makes rotational movements with the shoulder, without stopping the traction. Then the doctor presses with his fingers or fist on the head of the humerus in the upper-inner direction - as a rule, this reduces the dislocation.

The Hippocratic method is used to reduce dislocations in elderly patients and in cases where dislocation is combined with a fracture of the humeral neck.

The doctor holds the forearm with both hands and smoothly extends the limb. With the heel of his foot, he presses on the displaced head of the humerus. At the same time, he smoothly increases the extension of the arm and the load on the head. Reduction of the dislocation requires complete relaxation of the muscles, which is achieved with general anesthesia.

When correcting a traumatic dislocation, the following rules must be followed.

• The manipulation is performed using local or general anesthesia, since only in this case can complete muscle relaxation be achieved.
• The dislocated segment is repositioned in the most gentle way possible, without jerking or harsh force.
• After the dislocation has been corrected, the limb is immobilized with a plaster cast.
• After removing the fixing bandage, a course of rehabilitation treatment is carried out (therapeutic exercises, physiotherapy, hydrotherapy, mechanotherapy, aimed at relieving pain, normalizing blood circulation, increasing the elasticity of soft tissues).

The treatment of old and (especially) chronic dislocations is decided on an individual basis, since the prognosis is not always favorable.

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Surgical treatment

Patients with habitual dislocations should be referred to hospital for surgical treatment of the dislocation.