The human forearm is formed by ulna and radius. In between, a thick layer of connective tissue (Membrana interossea antebrachii) stretches out, connecting the two bones. Together with the humerus, ulna and radius form the elbow joint (Articulatio cubiti) by bending and stretching.
In addition, there are two articulated connections between the forearm bones, namely the proximal (pointing towards the middle of the body) and distal (pointing away from the middle of the body) radioulnar joint. These two joints enable rotational movements. The wrist is connected distally.
In addition to the bony parts, there are numerous stabilizing ligaments, muscles and tendons in the area of the forearm. Some structures, such as nerves or bursae, run superficially so that they can be damaged relatively easily. If pain occurs in the forearm, the timing, character and exact location of the symptoms often allow conclusions to be drawn about the diagnosis.
For example, a gradual onset of pain on the back of the elbow is an indication of bursitis. Sudden, severe pain in the forearm, on the other hand, may indicate a fracture. In the following text, the most common clinical pictures are discussed.
Diseases that lead to pain in the forearm
The entire extensor muscles (extensors) of the forearm originate at a small projection of the distal humerus, the radial epicondylus. This common tendon attachment of the muscles is irritated when subjected to heavy strain, so that a painful inflammation can develop. Frequently affected are tennis players, especially tennis beginners with insufficient stroke technique.
This is because the typical racket movement slightly overstrains the connector muscles. Thus the colloquial term “tennis elbow” has gained acceptance over the scientific name “Epicondylitis humeri radialis”. But also unaccustomed, non-sporting strains, such as gardening or carrying crates, can cause the symptoms.
Pain in the lateral elbow, which radiates into the forearm and is intensified during stretching movements, is characteristic of a tennis elbow. The affected epicondylus is painful under pressure, and is sometimes already recognizable from the outside by swelling or redness. The tennis elbow usually heals by frequent cooling (e.g.
with ice packs) and regular ‘stretching‘ of the forearm muscles (e.g. wrist flexion). In addition, tennis should be reduced to a pain-free level. If the muscle origin is in the epicondylus humeri medialis, also a bony projection of the distal upper arm, and the flexor muscles (flexors) are affected, this is called a golfer’s elbow.
In this injury, also known colloquially as ‘dislocation’, the joint surfaces of the bones involved leave their usual position as a result of external force. This results in a very painful malposition of the elbow joint. Often nerves or blood vessels are squeezed or injured, so that the pain radiates into the entire forearm.
Due to the high painfulness, the forearm is severely restricted in its movement! In most cases, the injury is caused by a violent fall on the outstretched arm. After the suspicion has been confirmed by X-rays, the joint must be put back into its original position.
This process is also known as reduction (‘settling’). It is not uncommon for the pain to be so severe that the operation must be performed under anesthesia. After successful reduction, a plaster cast is recommended for about one to two weeks.
Without immobilization, there is otherwise a risk that the elbow will dislocate again. Bursitis olecrani is an inflammation of the bursa of the elbow. Immediately behind the elbow, the bursa lies directly under the skin.
Chronic pressure, e.g. from prolonged desk work and the resulting support, can cause an inflammation (“student-elbow”). Characteristic is a pressure-sensitive swelling on the back of the elbow, which can reach the size of a hen’s egg. Frequently reddening and overheating of the affected skin areas can be observed.
The therapy consists of cooling the elbow and anti-inflammatory ointment (anti-inflammatory drugs).Forearm fractures are divided into fractures of the proximal (“upper arm”) and distal (“wrist“) forearm, as well as fractures of the forearm shaft. Proximal injuries include fractures of the radial head, i.e. the part of the radius that is involved in the formation of the elbow joint. Typically, the fracture is caused by a fall on the hand while the elbow is extended.
Due to pain, mobility is restricted after the accident and massive swelling and hematomas (“bruises”) appear on the elbow. First the forearm is x-rayed. If the fragments are displaced (dislocated) in relation to each other, they have to be brought to their original position in an operation and then stabilized by e.g. screw systems.
In the case of a fracture without dislocation, immobilization of the forearm is sufficient. The distal radius fracture is the most common bone fracture in humans. If the patient falls on the outstretched hand, the radius above the wrist will break.
In this case it is also called a ‘Colles fracture’. If the fall occurs with a bent position on the back of the hand, the resulting fracture is called a ‘Smith fracture’. A Colles fracture is easily recognized by the characteristic “bayonet position” of the wrist: The fragments of the radius shift towards the thumb, so that the hand is positioned bayonet-like to the forearm.
In cases of a non-displaced fracture, the only symptoms may be painful pressure and swelling. In most cases, however, severe pain and swelling are the rule immediately after the accident. The therapy depends on the exact type or fracture line of the injury.
If the injury does not include the wrist, the forearm is immobilized in a so-called “girl catcher bandage”. If there is a comminuted fracture or a fracture of the articular surfaces of the wrist, a reconstruction through surgery may be indicated. Due to the complicated course of nerves and vessels at the distal radius, complications in the healing process are not rare.
Fractures of the forearm shaft are often the result of traffic accidents or falls; they are caused by direct violent impact. Often both ulna and radius are affected. A special form of fracture is the so-called paper fracture: Direct violence (e.g. baseball bat attack) causes an isolated fracture of the ulna.
The pain affects the entire forearm. In addition, movements in the two joints between ulna and radius are painful and extensive hematomas and swellings can be observed. In most cases, surgery is performed on adult patients, and in the case of non-displaced fractures in children, a plaster cast may be sufficient in many cases. A dreaded complication is ossification of the connective tissue membrane interossea antebrachii between ulna and radius. In the worst case, the rotation of the forearm can be reversed.