Elbow joint dislocation

　　The dislocation of the elbow joint is mainly caused by indirect violence. The elbow is the connecting structure between the forearm and the upper arm, and the transmission and lever action of the violence are the basic external force forms that cause the dislocation of the elbow joint.

　　1. Posterior dislocation of the elbow joint

　　This is the most common type of dislocation, mainly affecting adolescents. When falling, the palm lands, the elbow is fully extended, and the forearm is in a supinated position. Due to the force of gravity and the ground reaction force, the elbow joint is hyperextended. The tip of the olecranon impacts the trochlear notch of the distal end of the humerus, forming a fulcrum of force. As the external force continues to increase, it causes the deltoid muscle attached to the olecranon and the anterior part of the elbow joint capsule to tear, resulting in posterior dislocation of the elbow joint with the olecranon moving backward and the distal end of the humerus moving forward. Since the distal end of the humerus forming the elbow joint is wide and thick in the medial and lateral epicondyle, and thin and flat in front and back, with the collateral ligament on the side to enhance its stability, but if there is a posterior-lateral dislocation, it is easy to cause avulsion fractures of the medial and lateral epicondyles.

　　2. Anterior dislocation of the elbow joint

　　Anterior dislocation is rare and often associated with olecranon fracture. The cause of injury is mostly direct violence, such as direct impact on the posterior aspect of the elbow or the elbow striking the ground in a flexed position, leading to olecranon fracture and anterior dislocation of the proximal end of the ulna. This type of injury causes severe soft tissue damage to the elbow, especially common in vascular and nerve injuries.

　　3. Lateral dislocation of the elbow joint

　　It is more common in adolescents. When the elbow is subjected to transmitted force, the elbow joint is in an internal or external rotation position, causing the lateral collateral ligament and the joint capsule of the elbow joint to tear, and the distal end of the humerus can move to the radial or ulnar side (i.e., the site of joint capsule rupture). Due to the strong internal and external rotation forces, the contraction of the forearm extensors or flexors can cause avulsion fractures of the medial and lateral epicondyles of the humerus, especially the medial epicondyle is more prone to fractures. Sometimes, fragments of the fracture can be trapped in the joint space.

　　4. Elbow joint split dislocation

　　This type of dislocation is very rare. When the upper and lower transmission forces concentrate on the elbow joint, the forearm is in an excessive pronation position, the annular ligament and the proximal interosseous membrane of the radius and ulna are split, causing the radial head to dislocate forward, while the proximal end of the ulna dislocates backward, and the distal end of the humerus is interposed between the two ends of the bone.

　　The posterior dislocation of the elbow joint sometimes occurs with injuries to the ulnar nerve and other nerves, fracture of the olecranon process of the ulna, and more often with fractures of the olecranon process during anterior dislocation.

　　I. Early complications

　　When the patient is injured, the muscles attached to the lateral epicondyle of the humerus contract, the joint capsule ruptures, and combined with direct external force, it can cause avulsion fracture of the lateral epicondyle. Due to the displacement during medial and lateral dislocation, the ulnar nerve and surrounding tissues are torn and moved inward or outward together, causing ulnar nerve traction injury. In addition, there may be vascular injury, so fractures, nerve injuries, vascular injuries, and infection are common early complications of elbow dislocation, and ischemic contracture may also occur.

　　II. Late complications

　　The complications in the late stage of elbow dislocation are often due to timely or inappropriate treatment, including joint stiffness, avascular necrosis, ossifying myositis, traumatic arthritis, and others.

　　When the elbow joint dislocates, attention should be paid to the symptoms and signs of vascular and nerve injuries, such as pain and abnormal activity of the elbow joint.

　　1. Swelling and pain in the elbow joint, the joint is placed in a semi-flexed position, and the extension and flexion movements are limited.

　　2. In the case of posterior dislocation, the elbow joint is elastically fixed at about 150° semi-extension, presenting a boot-shaped deformity. The back of the elbow is empty, and the olecranon is prominently protruding backward.

　　3. The circumference of the elbow joint is thickened, the distal end of the humerus can be felt in front, and the prominent olecranon can be felt behind. The bony landmarks behind the elbow lose their normal relationship.

　　4. Complicated with lateral dislocation can present with varus or valgus deformity of the elbow.

　　For elbow dislocation caused by sports, prevention is more important than treatment. The following are some methods of preventing dislocation:

　　1. Do a thorough warm-up before the activity, such as doing some circling and stretching exercises, so that each joint part gets sufficient movement.

　　2. Check whether the sports equipment is firm and whether the ground is level before the activity.

　　3. Take protective measures during activities, especially strengthen the protection of susceptible parts.

　　4. Do physical activities according to your strength, and do not perform dangerous actions beyond your capacity.

　　5. It is necessary to avoid direct impact of violence as much as possible and not to jump directly on hard ground (concrete ground).

　　X-ray auxiliary examination for elbow dislocation is the basis for diagnosis, and the anteroposterior and lateral views of the elbow joint can show the type of dislocation, the presence of associated fractures, and distinguish them from supracondylar fractures.

　　The X-ray signs of soft tissue around the elbow joint in traumatic fractures and dislocations include blurred, disappeared, and increased density in the muscle spaces. The change in the X-ray sign of the fat space in the elbow joint is an important indirect sign of joint capsule hemorrhage and effusion. When the joint capsule is torn after trauma, blood flows outside the joint capsule, and at this time, the fat space in the elbow joint appears blurred and unclear. When there is a large amount of effusion in the joint capsule, the anterior and posterior fat pads of the elbow joint are displaced to present a 'Chinese character sign'. When there is a small amount of effusion in the joint capsule, only the elevated and deformed fat space in the anterior elbow can be found. It is believed that observing the changes in X-ray signs of soft tissue around the elbow joint is of great clinical significance for avoiding the missed diagnosis of minor fractures of the elbow joint. It is also believed that the indirect signs of minor fractures and dislocations of the fat space in the elbow joint, which present as a 'Chinese character sign', are not only common in children and adolescents, but also common in adult patients.

　　Since elbow dislocation is usually caused by external force and has nothing to do with diet, patients with elbow dislocation only need to eat light, nutritious food, and should avoid smoking and drinking, as well as spicy and刺激性 food.

　　Elbow dislocation is manifested as swelling and pain in the elbow joint, the joint is placed in a semi-flexed position, and extension and flexion movements are limited. If there is posterior dislocation, the posterior aspect of the elbow is empty, and the olecranon is prominently突出的; in lateral dislocation, the elbow shows varus or valgus deformity. The elbow fossa is full. The relationship between the medial and lateral epicondyles and the olecranon, which forms an isosceles triangle, changes. When there is elbow dislocation, attention should be paid to the symptoms and signs of vascular and nerve injuries.

　　1. Non-surgical Treatment

　　The main treatment for new elbow dislocation or dislocation with fracture is manual reduction. For some short-term old fractures, manual reduction can be tried first. For simple elbow dislocation, the patient sits, local or brachial plexus anesthesia is applied, and if the injury time is short (within 30 minutes), anesthesia may not be required. The assistant holds the upper arm of the affected limb with both hands, and the operator holds the wrist with both hands, applying traction to flex the elbow joint to 60°-90°, and can slightly pronate. Often, a reduction sound or vibration can be heard. After reduction, the elbow joint is fixed in a functional position with an upper limb cast. The cast is removed after 3 weeks, and active functional exercises are performed. Physical therapy can be supplemented if necessary, but strong passive activities should not be done.

　　Elbow dislocation with avulsion fracture of the medial epicondyle: The reduction method is basically the same as that for simple elbow dislocation. At the time of elbow reduction, the medial epicondyle usually can be reduced. If the fracture fragment is caught in the joint cavity, the elbow is abducted (laterally) during upper arm traction to increase the medial joint space, and the avulsion fracture fragment is dislocated from the joint and reduced with the help of the flexor muscles of the forearm. If the fracture fragment is dislocated from the joint but still displaced, manual reduction is added, and pressure shaping is applied during cast fixation. There are also cases where the fracture fragment is caught like a button and cannot be reduced, and surgical incision should be considered.

　　Old Traumatic Elbow Dislocation (Early): Defined as old dislocation if it exceeds 3 weeks. It is usually difficult to reduce the joint after 1 week. There may be joint hematoma organization, granulation tissue formation, and adhesion of the joint capsule. Manual reduction of old elbow dislocation is performed under brachial plexus anesthesia, with gentle extension and flexion of the elbow to gradually release adhesions. The elbow is slowly extended, and the elbow is gradually flexed under traction. The operator uses both thumbs to press on the olecranon and pushes the distal end of the humerus backward to reduce it. After confirming the reduction with X-ray, the elbow joint is fixed slightly with an upper limb cast.

　　2. Surgical Treatment

　　(1) Indications for surgery

　　① Failure of closed reduction, or not suitable for closed reduction, this situation is rare, often accompanied by severe elbow injury, such as fractures of the olecranon with separation and displacement.

　　② Elbow joint dislocation with avulsion fracture of the medial epicondyle of the humerus. When the elbow joint is reduced and the medial epicondyle is still not reduced, the medial epicondyle should be reduced or internally fixed by surgery.

　　③ Old elbow joint dislocation, not suitable for closed reduction.

　　④ Some habitual elbow joint dislocations.

　　(2) Open Reduction

　　Brachial plexus anesthesia. Make a longitudinal incision at the posterior side of the elbow, expose and protect the ulnar nerve at the posterior side of the medial epicondyle of the humerus. Make a lingual incision in the triceps tendon. After exposing the elbow joint,剥离 surrounding soft tissue and scar tissue, and remove blood clots, granulation tissue, and scars from the joint cavity. Identify the relationship between the joint bone ends and realign them. Suture the surrounding tissue. To prevent recurrence of dislocation, a Kirschner wire can be used to fix from the olecranon to the distal end of the humerus, and it can be removed after 1-2 weeks.

　　(3) Arthroplasty

　　Mostly used for old elbow joint dislocation, where the cartilage surface has been destroyed, or for those with joint stiffness after elbow injury. Brachial plexus anesthesia. Make a posterior incision on the elbow, cut through the triceps tendon. Expose the articular ends of the elbow joint. Cut off the distal end of the humerus, retaining part of the medial and lateral epicondyles. Cut off the tip of the olecranon process and part of the dorsal bone, and also make the acromial tip smaller. Retain the articular cartilage surface, and if the radial head does not affect joint movement, it can be retained, otherwise, the radial head should be cut off. According to the newly formed joint space, if it is narrow, appropriate central resection of 0.5cm of the distal end of the humerus can be made in a fork shape. The ideal gap distance should be 1-1.5cm.

　　Arthroplasty of the joint between the interosseous membrane of the iliotibial band is effective for the stiff elbow joint. Pay attention to the deep surface of the iliotibial band facing the joint cavity when sewing the joint surface and joint capsule. Check the wound after sewing the joint surface, align the elbow joint, observe the condition of arthroplasty, and suture the wound in layers. After surgery, use an upper limb splint to fix the elbow joint at 90° and the forearm at the intermediate position between pronation and supination. Elevate the injured limb, and move the fingers. After a few days, wear the upper limb splint for functional exercise, remove the fixation after about 3 weeks, strengthen the functional exercise of the injured limb, and assist with physical therapy.