Classification and injury mechanisms
According to the AO/ASIF Universal Classification of Fractures, diaphyseal injuries (segment 22) are divided into three types:
- Type A — simple fractures;
- Type B — wedge fractures;
- Type C — complex fractures.
A fracture may involve only a single bone (radius or ulna) or both simultaneously. Isolated injuries of a single bone typically occur from direct trauma, such as a heavy blow to the forearm. When both bones break, the mechanism can be either direct or indirect. In an isolated fracture of the ulna, the fragments do not displace along the length because the intact radius acts as a natural splint. However, if both bones are broken, complex multi-plane displacement occurs, including rotational displacement, and the forearm itself is shortened.
Symptoms and diagnosis
The presence of a fracture can be assessed by deformity, soft tissue swelling, and patient complaints. The clinical presentation depends on which specific bone is injured:
- Isolated ulnar fracture. The continuity of the ulnar crest, which is easily palpable beneath the skin, is disrupted. Movements (flexion, extension, rotation) are possible but restricted due to pain.
- Isolated radial fracture. The radius is concealed by a bulk of muscles, so external deformity is often subtle. Active pronation and supination (forearm rotation) are completely absent, and during attempted passive rotation, the radial head remains stationary.
- Fracture of both bones. The forearm is severely deformed and shortened. Pronounced pathological mobility and bone crepitus are detected. Hand function is severely impaired.
Two specific pain symptoms are characteristic of all fracture types: pain upon axial loading and pain upon convergent loading (transverse compression of the forearm bones away from the injury site).
A definitive diagnosis is established using radiography. The radiograph must be taken in two standard projections, capturing both the elbow and wrist joints simultaneously. This allows for an accurate assessment of the displacement pattern and helps rule out associated dislocations.
Pre-hospital care and conservative treatment
At the pre-hospital stage, it is necessary to administer analgesia and apply a transport splint. In fractures of both bones, the splint is applied to three sides of the forearm to prevent unstable fragments from damaging blood vessels and nerves.
Conservative treatment is primarily indicated for fractures without displacement or with fragment displacement of less than half the bone diameter. The arm is immobilized in a plaster cast (from the metacarpal heads to the shoulder), with the elbow joint flexed at a 90° angle.
The position of the hand in the cast strictly depends on the level of the injury:
- Upper third: maximum supination or neutral position (to approximate the fragments).
- Middle third: semi-pronation position.
- Lower third: the forearm is reduced in pronation and then placed in semi-pronation.
The duration of immobilization ranges from 8 to 12 weeks, depending on the severity of the injury. During the period of cast wear, serial radiographic monitoring is critically important, as the risk of secondary bone displacement within the cast is very high.
Surgical treatment
Surgical intervention is the method of choice for the majority of displaced diaphyseal forearm fractures. Indications for surgery include the impossibility of closed reduction, interposition of soft tissues between fragments, and a high probability of secondary displacement in a cast. If manual reduction fails, repeated attempts should not be made — the patient is immediately prepared for surgery.
Osteosynthesis is performed using bone plates (angle-stable implants are preferred) or intramedullary nails. The main advantage of stable osteosynthesis is the ability to forego external plaster immobilization in the postoperative period. This allows for early initiation of mobilization exercises and prevents the development of persistent joint contractures. Working capacity is restored 16–18 weeks after surgical treatment.
Briefly: answers to topical questions
What are the indications for surgical treatment of diaphyseal forearm fractures?
An indication for surgical treatment is practically any diaphyseal forearm fracture with fragment displacement. Specific indications in children include:
- open complicated fractures;
- complete dislocation of fragments into the interosseous space;
- re-fracture with displacement;
- recurrent displacements when proper position cannot be maintained after closed reduction;
- presence of two fractures along the same bone;
- circulatory disturbances;
- compartment syndrome;
- soft tissue interposition;
- associated injuries.
Which muscles cause typical rotational displacement of fragments in radial diaphysis fractures?
The following muscles participate in fragment displacement during forearm bone fractures:
- biceps brachii muscle (m. biceps brachii);
- supinator muscle (m. supinator);
- pronator teres muscle (m. pronator teres);
- pronator quadratus muscle (m. pronator quadratus).
Displacement depends on the level of the fracture.
What specific complications can occur in diaphyseal forearm fractures and their treatment?
Specific complications and adverse outcomes in diaphyseal forearm fractures include:
- displacement of the bone fragment with early mobilization;
- persistent limitation of joint mobility (contracture) with delayed mobilization;
- limitation of rotational movements due to callus formation;
- compartment syndrome, which in children is an indication for surgical treatment.
What are the complete rules for applying a transport splint for a fracture of both forearm bones at the pre-hospital stage?
At the pre-hospital stage, transport immobilization of the upper extremity is performed from the upper third of the arm to the fingers. The elbow joint is fixed in a flexed position. General analgesic therapy is administered.
Class and exam questions
Why do fragments not undergo lengthwise displacement in an isolated ulnar fracture?
In this case, the intact radius assumes the function of a natural splint. It maintains the overall length of the segment and prevents the ulnar fragments from shifting along the axis.
What is the golden rule when performing X-rays of the forearm bones?
Radiographs must be taken strictly in two standard projections, and the image must include two adjacent joints — the wrist and the elbow.
Is it permissible to apply heat or massage the arm after a forearm fracture?
No. Thermal procedures, massage of the elbow joint area, and forceful movements are strictly contraindicated, as they provoke the formation of heterotopic ossification and the development of persistent contractures.
What else to study on this topic
- Clinical features and treatment of isolated ulnar shaft fractures
- Specifics of reduction in isolated radial shaft fractures
- Algorithm for applying a long arm posterior plaster splint
- Possible complications following plate osteosynthesis
- Principles of early rehabilitation after stable osteosynthesis
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