What are Forearm Dislocations?
Traumatic dislocations and subluxations of the forearm in frequency take second place after dislocations of the shoulder and make up 18-27%. They are observed more often in men 10-30 years old and in women 50-70 years old.
Causes of Dislocation of the Forearm
Dislocations and subluxations of the forearm arise as a result of direct and indirect injury. The variety of dislocations in the elbow joint is explained by the complexity of its anatomical structure.
Pathogenesis during Dislocations of the Forearm
There are dislocations of the bones of the forearm posterior, anterior, outward, inward; dislocations and subluxations of the radial head anteriorly, posteriorly and outwardly; divergent dislocation of the forearm. Subluxations include cases where partial contact is maintained between the articular surfaces.
The course and outcome of a dislocation or subluxation of the forearm depends not only on the magnitude in the form of displacement, but also on the nature of the damage to the soft tissues surrounding it. Usually a forearm dislocation is accompanied by a hematoma, damage to the capsule-ligamentous apparatus, muscles, periosteum and, in some cases, compression of blood vessels and nerves. Soft tissue injuries are directly dependent on the magnitude and direction of the acting force. This can explain the fact why the same type of dislocation in different patients proceeds and ends far from the same.
Symptoms of Dislocations of the Forearm
Most often (90%) there are posterior forearm dislocations. According to experimental data, they occur when falling on a hand slightly bent at the elbow joint. With an increase in abduction of the forearm, the lateral ligaments are significantly damaged. Separations of the medial ligament with a fragment of the medial epicondyle or coronoid process are possible, in children – epiphysiolysis of the medial epicondyle. The result of shear compression forces in the brachioradial joint are fractures of the radial head, capitate head elevation or lateral epicondyle of the shoulder. With a posterior dislocation, more often than with other types, damage to the radial, median and ulnar nerves, brachial artery occurs, the brachial muscle is significantly injured.
When the forearm is dislocated from the back due to its displacement in the proximal direction, the impression of shortening the forearm and lengthening the shoulder is created. The axis of the forearm is deflected (usually outwards) with respect to the axis of the shoulder. The ulnar process will stand posteriorly, its apex is displaced upward and is located above the level of the condyles of the shoulder. This distinguishes a dislocation from a supracondylar fracture of the shoulder, in which the Güter triangle formed by the apex of the ulnar process and both epicondyle of the humerus is not broken.
Dislocations of the forearm in front are less common (about 4.5%). They occur when falling on the most bent elbow joint. With anterior dislocation at the site of the ulnar process, retraction is noted, the forearm seems elongated compared to the forearm of a healthy arm. This type of dislocation is characterized by more or less damage to both lateral ligaments of the anterior and posterior sections of the joint capsule. Possible damage to the tendon of the triceps muscle of the shoulder, tearing of muscles attached to the condyles of the shoulder.
Lateral and medial dislocations of the forearm are very rare. The elbow joint is expanded in the transverse direction. The axis of the forearm is shifted outward or inward, respectively. These types of forearm dislocations are often combined with a fracture of the medial or lateral epicondyle of the humerus, head of the radius.
A diverging dislocation is extremely rare. It occurs when the ulnar and radial bones diverge backward, forward, inward or outward, is a consequence of brute force. Not only the capsule-ligamentous apparatus of the elbow joint is damaged, but also the interosseous membrane.
Diagnosis of Dislocations of the Forearm
Diagnosis of a dislocation of the forearm is usually straightforward. Patients are concerned about the forced position of the limb, the impossibility of movements in the elbow joint, severe pain in it. In all cases, there is a deformation of the elbow joint depending on the type of dislocation, and swelling of this area is expressed. When you try to make passive movements, a symptom of “springy mobility” is detected.
X-ray examination of patients with dislocations of the forearm is mandatory before and after reduction. On radiographs of the elbow joint, concomitant fractures of the coronoid process, radial head, capitate head elevation, or medial epicondyle are determined.
Dislocations of the forearm are accompanied by damage to the capsule-ligamentous apparatus of the elbow joint. The lateral ligaments are damaged during or with the separation of the bone fragment. The main stabilizer of the elbow joint is the medial ligament. With its integrity, dislocation in the elbow joint does not occur. After eliminating the dislocation of the forearm, it is necessary to determine the latent instability of the elbow joint for the prevention of chronic instability.
Of great help in the early diagnosis of damage to the capsule-ligamentous apparatus of the elbow joint is the X-ray contrast study, in which a contrast medium (verographin, urographin) is injected into the joint cavity. In the presence of a defect in the capsule-ligamentous apparatus, the contrast medium is determined in paraarticular tissues.
Treatment of Dislocations of the Forearm
In fresh cases, the forearm dislocation is eliminated either under local anesthesia with the introduction of 20-25 ml of a 2% solution of novocaine into the joint cavity or under anesthesia. Reduction of dislocation under general anesthesia is preferable due to better relaxation of the surrounding muscles to prevent additional injury to the capsule-ligamentous apparatus and articular cartilage.
Direction of the rear dislocation of the forearm. The patient is laid on his back, his sore arm is taken away from the body to the right angle. The surgeon becomes outward from the designated shoulder and with both hands grabs the lower part of the shoulder above the elbow joint, puts the thumbs on the ulnar process and the head of the radius. The assistant becomes on the same side to the right of the surgeon and takes the patient’s hand with one hand and the lower part of the forearm with the other. The surgeon and assistant make a smooth extension of the hand while bending it in the elbow joint. The surgeon, pressing on the ulnar process and the head of the radius, shifts the forearm anteriorly, and the shoulder posteriorly. Reduction usually occurs without much effort, and a clicking sound occurs.
With a posterior forearm dislocation, the surgeon presses the ulnar process and the radius head with the thumb, not only in front, but also inside.
Direction of the front dislocation of the forearm. The patient is placed on a dressing table, his hand is taken to a right angle. The assistant fixes and counter-extends the shoulder, and the surgeon, pulling the forearm with one hand and pressing on the proximal part of the forearm in the direction from below, outside and behind with the other hand, bends the forearm in the elbow joint.
Direction of dislocation of the forearm inside. The patient is laid on the table, the shoulder is taken to the right angle. One assistant fixes and holds the shoulder, the other exercises traction along the forearm along the axis. The surgeon with one hand presses on the proximal part of the forearm from the inside from the outside, and with the other hand simultaneously presses on the external condyle of the shoulder from the outside to the inside.
Direction of external dislocation. The assistant fixes the allotted shoulder, and the surgeon with one hand extends beyond the forearm, with the other presses on the upper part of the forearm inside and behind, bending the elbow joint.
After eliminating the dislocation of the forearm, it is necessary to check the pulse on the radial artery, movement in the joint to exclude capsule infringement, lateral joint stability. An x-ray examination is mandatory: standard radiographs, contrast arthrograms and radiographs with valgus of the forearm.
If the joint is stable or instability is established I degree, conservative treatment is indicated. Immobilization is carried out by a plaster cast applied from the shoulder to the metacarpophalangeal joints when the elbow joint is bent at an angle of 90 °, on average between the pronation and supination position for a period of 2-3 weeks, depending on the data of the radiopaque study.
From the very first days, the patient is recommended to carry out active movements with the fingers of the hand, which contributes to the resorption of edema and hemorrhage in the elbow joint. From the 2-3rd day, isometric tension of the muscles surrounding the ulnar joint begins.
After removing the plaster casts, rehabilitation treatment is performed.
An indication for surgical treatment is lateral instability of the elbow joint of the II-III degree. At the same time, the lateral capsule-ligamentous apparatus is carefully sutured, rare sutures are applied to the capsule of the front and rear sections. The period of immobilization is determined depending on the extent of damage to the capsule-ligamentous apparatus, the age and profession of the victim.
Treatment of dislocation of the forearm with separation of the medial epicondyle of the shoulder. In the absence of displacement of the epicondyle after the elimination of the dislocation of the forearm, the treatment is conservative. Displacement of the epicondyle more than 2 mm and its possible infringement in the joint cavity are indications for surgical intervention. In this case, the epicondyle or its fragment is removed from the joint cavity and, depending on the size, is fixed with a screw, knitting needles or transosse lavsan sutures. Suture interligamentary breaks.
Treatment of dislocation of the forearm with a fracture of the coronoid process. The size of the torn fragment and the stability of the joint are taken into account. If the joint is stable, conservative treatment is performed after elimination of the dislocation of the forearm. In the presence of lateral loosening, surgical treatment is indicated to avoid the development of chronic instability. Intervention is via anteromedial access. With a large fragment of the coronoid process, it, together with the medial ligament attached to it, is fixed to the base with two or three transosseous dacron sutures or a screw. Small fragments are removed, the ligament is sutured with transosseous sutures.
Treatment of dislocation of the forearm with a fracture of the radial head. In case of fractures of the head and neck of the radius without displacement after the elimination of the dislocation of the forearm, conservative treatment is performed. If there is a displacement of the head or its fragment, resection of the broken head or removal of the fragment in the next 1-3 days after damage is indicated. In this case, careful closure of the damaged capsule-ligamentous apparatus is very important.