Elbow deformity

Introduction The elbow joint is one of the most stable joints of the human body. The maintenance of its stability depends on the integrity of the joint structure. The maximum flexion and extension can reach 160°, the pre-rotation can reach 85°, and the rotation can be about 80°. The long axis of the humerus is 6° valgus angle and the internal rotation angle is 5°7° with the intercondylar axis. The axis of flexion and extension of the elbow joint is located at an angle of 40° with the humeral shaft in front of the midline of the humerus. Elbow joint dislocation, fracture and other reasons can lead to elbow joint deformity.

Cause

(1) Causes of dislocation of elbow joint

Mostly indirect violence, and occasional direct violence can also cause injury.

(B) the pathogenesis of elbow dislocation

Dislocation of the elbow is mainly caused by indirect violence. The elbow is the coupling structure between the forearm and the upper arm. The violent conduction and leverage are the basic external forces that cause dislocation of the elbow joint.

1. Dislocation of the elbow joint

This is the most common type of dislocation, with adolescents as the main target. When falling, the palm of the hand touches the ground, the elbow joint is fully extended, the forearm is rotated, and the elbow joint is overextended due to human gravity and ground reaction force. The top of the olecranon violently impacts the olecranon socket at the lower end of the humerus, which forms the fulcrum of force. The external force continues to strengthen the anterior partial tear of the tibialis anterior and elbow joint capsules attached to the condyle, causing the ulnar olecranon to shift backward, while the lower end of the humerus is displaced forward.

Because the inner and outer humerus of the lower end of the humerus forming the elbow joint is wide and thick, the front and back are flat and thin, and the collateral ligament is strengthened on the side. However, if the lateral dislocation occurs, the avulsion fracture of the internal and external ankle is easy to occur.

2. Anterior dislocation of the elbow joint

Pre-dislocation is rare, and often combined with olecranon fracture. The cause of the damage is mostly direct violence, such as direct impact on the elbow or impact of the elbow on the ground in the flexion position, resulting in fracture of the olecranon and proximal dislocation of the ulna. This type of injury to the elbow soft tissue injury is more serious.

3. Lateral dislocation of the elbow joint

It is more common for teenagers. When the elbow is subjected to conduction violence, the elbow joint is in an inversion or valgus position, causing the collateral ligament and joint capsule of the elbow joint to tear. The lower end of the tibia can be moved to the temporal or ulnar side (ie, the joint capsule rupture). Bit. Due to strong internal and external valgus, due to the violent contraction of the forearm extension or flexor muscles, the internal and external iliac avulsion fractures are caused, especially in the humerus. Sometimes the fracture piece can be embedded in the joint space.

4. Elbow joint dislocation and dislocation

This type of dislocation is extremely rare. Because the upper and lower conduction violence is concentrated on the elbow joint, the forearm is excessively pronation, the annular ligament and the proximal interosseous membrane of the ulna and radius are cleft, causing the humeral head to dislocate to the front and the proximal ulna dislocation. The lower end of the humerus is inserted between the ends of the two bones.

an examination

Related inspection

Joint cavity fluid examination synovial fluid routine examination of bone and joint soft tissue CT examination

1. Special manifestations of dislocation: the elbow is obviously deformed, the elbow is full, the forearm is short, the ulnar olecranon is protruding, and the back of the elbow is emptied and sunken. The joint elasticity is fixed at 120 to 140 degrees with only a small passive activity. The relationship between the bone marks of the elbows changes. Under normal circumstances, when the elbows are straight, the olecranon and the humerus are in a straight line at three points. When the elbow is elbowed, it is an isosceles triangle. The above relationship was destroyed during dislocation, and the triangular relationship remained normal when the humerus was fractured. This is the main point to identify the two.

2. The complication of elbow dislocation: posterior dislocation sometimes combined with ulnar nerve injury and other nerve injuries, ulnar condyle fracture, anterior dislocation with olecranon fracture.

3. X-ray examination: the positive lateral slice of the elbow joint can show the type of dislocation, the combined fracture, and is different from the supracondylar fracture.

The disease can have the following complications:

First, early complications of joint dislocation:

When the patient is injured, the muscles attached to the external malleolus of the humerus contract, the joint capsule ruptures, and then combined with direct external force, can cause avulsion fracture of the external malleolus. Due to the displacement of the inward and lateral dislocations, the ulnar nerve and the surrounding tissue are avulsed and displaced inward or outward, which may cause ulnar nerve traction injury, and may also involve blood vessel damage. Therefore, fractures, nerve damage, vascular injury, and infection are common early complications of elbow dislocation. Volkmann ischemic contracture can also be concurrently performed.

Second, the late complications of joint dislocation:

Late complications are mostly caused by patients who are not treated or treated improperly, including joint stiffness, avascular necrosis, ossifying myositis, and traumatic arthritis.

Differential diagnosis

The diagnosis basis of this disease: a history of trauma, the most common to fall to the palm of the hand. The affected area is swollen, painful, and inactive. The patient holds the affected side of the forearm with a healthy hand. The elbow joint is in a semi-extended position, and the elbow is not stretched during passive movement. The emptiness behind the elbow can be touched into the depression. The three-point relationship between the elbows is completely destroyed and the normal relationship is lost. X-ray examination can confirm the diagnosis.

1. Identification of total iliac crest separation and elbow dislocation:

Pediatric X-ray film on the humeral small skull center has not appeared, only by X-ray film diagnosis, it is easy to be misdiagnosed as elbow dislocation. Because the strength of the tarsal in children is far less than the joint capsule and ligament, the damage to the joints of children should first consider the possibility of osteophyte injury. Secondly, careful and comprehensive clinical examination is also a very important part. According to the swelling, tenderness and blood stasis, there is a preliminary impression on the fracture site. Some special bone markers such as the elbow posterior triangle are used to diagnose and identify the epiphysis of the lower end of the humerus and the dislocation of the elbow joint. Third, familiar with the anatomical morphology and physiological evolution of elbow joints in children, in order to improve the diagnostic coincidence rate when reading X-ray films, so as to avoid misdiagnosis and mistreatment, and have serious consequences for the growth and development of children.

2. Identification of anterior elbow dislocation and straightening Monteggia fracture with ulnar olecranon fracture:

The main clinical feature of anterior dislocation of the elbow joint with ulnar olecranon fracture is fracture of the proximal ulna, and the distal end of the humerus passes through the olecranon to cause anterior dislocation of the elbow joint. Because of the high energy trauma, the proximal ulna is mostly complicated comminuted fracture, and a few can also occur in the simple oblique fracture of the olecranon. Most of the ankle joints were accompanied by dislocation, but there was no separation of the upper and lower jaw joints. The main points of diagnosis are:

(1) anterior dislocation of the elbow joint;

(2) proximal ulnar fracture;

(3) There is no separation of the upper ulnar joint.

Because this injury is accompanied by ankle dislocation, the clinical is easily confused with the straightening Monteggia fracture, which should be identified at the time of diagnosis.

3, humeral supracondylar fracture and elbow dislocation:

(1) When the supracondylar fracture of the humerus (shoulder type), the elbow joint can be partially moved, the triangle of the elbow does not change, the upper arm is shortened, and the forearm is normal.

(2) When the elbow joint is dislocated, the elbow joint is elastically fixed, the elbow triangle is changed, the upper arm is normal, and the forearm is shortened.

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.