Forearm Injuries and Fractures

Injury to the forearm usually results from trauma secondary to, for example, a fall, a road traffic accident or a sporting injury. It can also result from overuse. Injuries include muscle strain and contusion, crush injuries, fractures and tendon and nerve injuries.

Anatomy of the forearm

The radius and ulna have an important role in positioning the hand. The ulna has a stabilising role, while the radius is articulated in a way which allows it to roll over the ulna, moving the hand from supination (external rotation) to pronation (internal rotation).

The two bones of the forearm are the radius, laterally, and the ulna, medially. Other components of the forearm include skin, blood vessels, and soft tissue.
At its upper end, the radius articulates with the capitulum of the humerus at the elbow, and with the ulna (superior radioulnar joint). At its lower end it articulates with the scaphoid and lunate bones and also with the ulna (inferior radioulnar joint).
At its upper end, the ulna articulates with the trochlea of the humerus, and with the head of the radius (superior radioulnar joint). At its lower end it articulates with the radius (inferior radioulnar joint).
The olecranon process at the upper end of the ulna forms the prominence of the elbow. The styloid processes of the radius and the ulna form prominences at the wrist.

Forearm fractures

Forearm fractures account for most limb fractures.¹ Wrist fractures are the most common forearm fracture.¹Fracture risk factors include osteoporosis (more common in women than men) and malignancy (pathological fractures).

Classification

Forearm fractures can be classified as either proximal, middle or distal.
They can affect one or both forearm bones.
They are either open or closed.
Proximal forearm fractures may involve the elbow joint (see Elbow Injuries and Fractures article, for Monteggia fractures see below).
Distal forearm fractures may involve the wrist (see Wrist Fractures article).

General assessment and initial management of forearm fractures

Some general principles should be followed for all forearm fractures. Specific points related to the different fracture types are discussed below. Forearm fractures in children can generally be treated differently from adult fractures because of continuing bone growth in the radius and the ulna after the fracture has healed.²

Assess Airway, Breathing and Circulation and manage as necessary.
Assess upper limb neurovascular function
- Sensory function: the median nerve supplies the thumb, index, middle and radial half of the ring finger on the palmar side of the hand and the tip of the thumb, index, middle and ring finger on dorsum of the hand; the radial nerve supplies the dorsolateral aspect of the hand and the dorsal aspect of the thumb, index, middle and lateral half of the ring fingers; the ulnar nerve supplies the dorsal and palmar aspects of the medial half of the ring finger and the whole of the little finger.
- Motor function: test anterior interosseous branch of the median nerve by asking patient to make the 'OK' sign; test radial nerve by asking patient to extend their fingers or wrist against resistance; test ulnar nerve by asking patient to separate their fingers against resistance.
- Vascular function: examine radial (and ulnar) pulse. Assess capillary refill.
Examine the wrist, elbow and forearm for tenderness and range of motion.
Perform a complete examination for other injuries.
Immobilize the forearm and upper arm whilst waiting for Xray.
Provide analgesia.
Immediate fracture reduction is required if there is neurovascular compromise, severe displacement or skin tenting.

Adult both-bone forearm fractures

Mechanism of injury: usually significant force injury.¹ Most commonly occur in motor vehicle accidents, also occur from direct blow, fall from a height or during sport.
Presentation: pain and swelling at site with obvious deformity.
Assessment: may be nerve involvement with paraesthesiae, paresis or loss of function. Do not elicit crepitus as may cause further soft tissue injury. Do not probe open fractures as may cause deeper contamination.
Investigation: X-ray entire length of forearm, wrist and elbow, with AP and lateral views.
Management: displaced fractures are the usual situation in adults. Operative treatment with internal fixation or intramedullary nailing will be needed in nearly all cases, so refer urgently. Closed reduction may be attempted (with sufficient sedation/analgesia ± muscle relaxants) if there is acute neurovascular compromise.

Paediatric both-bone forearm fractures

Fractures may be of greenstick type (incomplete) or complete. A greenstick fracture can occur in one bone with a complete fracture in the other. Complete fractures may be undisplaced, minimally displaced or overriding. Fractures of the proximal third are relatively rare. Middle third fractures account for about 18% of both-bones fractures and distal third about 75%.³

Mechanism of injury: usually an indirect injury following fall on outstretched hand. Occasionally caused by direct trauma.
Presentation: pain, swelling and deformity at fracture site.
Investigation: X-rays of wrist, elbow and whole forearm should be taken.
Management: unlike adults, many both-bone fractures of the forearm can be treated by closed reduction. After reduction, forearm pronation and supination should be checked and arm placed in a long-arm cast or splint. Surgical treatment is by open reduction and plating/intramedullary nails depending on degree of overriding/angulation.³

Radial shaft fractures (Galleazzi fractures)

Definition: solitary fractures of the distal one third of the radius with accompanying subluxation or dislocation of distal radioulnar joint (DRUJ). Synonym is reverse Monteggia fracture.⁴
Mechanism of injury: commonly caused by fall on extended, pronated wrist.
Presentation: pain, swelling and deformity of the wrist and forearm. Tenderness and swelling at the distal radius and tenderness at DRUJ.
Investigation: X-ray the entire length of the forearm including wrist and elbow joints, AP and lateral views usually sufficient.
Management: in adults, requires surgical open reduction of the distal radius and DRUJ with internal fixation. In children the fracture can often be treated by closed reduction with longitudinal traction and correction of radial angulation. General anaesthesia may be required in difficult cases. If closed reduction under GA fails, K-wire insertion may be needed to lever the fracture into position. Open reduction may be needed in some cases.⁴

Ulna shaft fractures

Definition: isolated mid-shaft ulna fractures have the synonym 'nightstick fracture'.
Mechanism of injury: usually caused by a direct blow to the ulnar border, classically if someone receives a blow from an object whilst raising their arm in defence.⁵
Presentation: point tenderness over ulna shaft and forearm swelling.
Investigation: need to x-ray ulna from wrist to elbow.
Management: require orthopaedic referral. Non-displaced or minimally-displaced fractures can be treated with posterior splint from mid-upper arm to dorsum of the metacarpal joints with wrist in slight extension, forearm in neutral position and elbow at 90°. After 7-10 days, when swelling has subsided, use plaster sleeve or functional brace for next 4-6 weeks. Monitor weekly for first 3 weeks for any displacement. Fractures with marked displacement or angulation should be treated with open reduction and internal fixation.

Monteggia fractures

Definition: these are fractures of the proximal third (usually) of the ulna with associated dislocation of the radial head. Classified as:
- Type I - Fracture with anterior radial head dislocation. Commonest (60%).⁶
- Type II - Fracture of the proximal ulna with posterior or posterolateral dislocation of the radial head (15%).⁶
- Type III - Fracture of the ulna metaphysis with lateral or anterolateral dislocation of the radial head (20%).⁶
- Type IV - Fracture of both radius and ulna at their proximal third with anterior dislocation of radial head (5%).⁶
Mechanism of injury: usually caused by a fall onto outstretched, extended and pronated elbow or direct blow.
Presentation: acute, severe pain and swelling in forearm and elbow. Damage may occur to the posterior interosseous nerve.
Investigation: X-ray the entire length of radius and ulna, including wrist and elbow, AP and lateral views usually sufficient but may need radiocapitellar views.
Management: in adults, immobilize joint in splint and refer for open reduction and internal fixation. Most paediatric monteggia fractures are treated closed.⁷

Isolated proximal ulna fractures are rare. Always examine for a Monteggia fracture/dislocation.¹

Complications of forearm fractures

See general article entitled 'Complications from Fractures'.

Non-union and malunion (uncommon)⁸
Compromise of brachial/radial artery blood supply
Median, ulnar or radial nerve injury
Infection (more likely if fracture secondary to crush injury)⁸
Compartment syndrome (more common in both-bone forearm fractures)
Radioulnar fusion (synostosis)
Re-fracture

Prevention of forearm fractures

Prevention of osteoporosis.
Adequate treatment of existing osteoporosis.
The use of wrist and elbow guards whilst taking part in certain sports activities such as mountain biking and skating.

Forearm overuse injuries⁹

Apart from tennis and golfer's elbow, forearm overuse injuries are not that common outside the realms of sports medicine.
Commonly affect athletes who take part in racket or throwing sports. If an activity involves repetitive flexion-extension of the elbow or pronation-supination of the wrist, it can lead to an overuse injury.
Examples of overuse injuries around the elbow are lateral and medial epicondylitis - see separate article on tennis and golfer's elbow.
Ulnar nerve injury and olecranon stress fractures can also occur if there is increased stress on the elbow joint.
Three major nerves cross the elbow joint: the median nerve, the ulnar nerve and the radial nerve. Overuse injuries or direct trauma to the elbow can affect these nerves.
Pronator syndrome and radial tunnel syndrome can occur in sports where there is excessive wrist flexion-extension or pronation-supination.
History taking is an essential part of the examination.

Pronator syndrome

Due to entrapment of the median nerve.
There is pain or paraesthesia over the median nerve distribution in the anterior proximal forearm. Aggravated by throwing/swinging a racket.
Distinguished from carpel tunnel syndrome because in carpel tunnel syndrome, sensation over the thenar eminence is preserved (the sensory branch of the median nerve that innervates the thenar eminence does not pass through the carpel tunnel).
Negative Tinel and Phalen tests at the wrist in pronator syndrome and difficulty making the OK sign (touching the tips of the 1st and 2nd fingers with the thumb).
Treatment is rest/modification of activity, ice, analgesia, physiotherapy and occupational therapy.

Radial tunnel syndrome

Due to entrapment of the radial nerve.
Pain experienced distal to the lateral epicondyle of the humerus and radiates down the dorsum of the forearm.
Often misdiagnosed as lateral epicondylitis.
A Tinel test approximately 6cm distal to the lateral epicondyle over the radial nerve can reproduce pain. Also pain on resisted supination with forearm extended.
Treatment is rest/modification of activity, ice, analgesia, physiotherapy and occupational therapy.

Document references

Huang E, Grimes P; Fractures, Forearm. eMedicine. Last Updated February 24, 2005.
Rodriguez-Merchan EC; Pediatric fractures of the forearm. Clin Orthop Relat Res. 2005 Mar;(432):65-72. [abstract]
Wheeless' Textbook of Orthopaedics; Pediatric Both Bone Forearm Fractures. Duke Orthopaedics. Cited from textbook online October 2007.
Wheeless' Textbook of Orthopaedics; Galeazzi's Fracture (Adults). Duke Orthopaedics. Cited from textbook online October 2007.
Wheeless' Textbook of Orthopaedics; Ulna/Ulnar Shaft Fracture. Duke Orthopaedics. Cited from textbook online October 2007.
Wheeless' Textbook of Orthopaedics; Monteggia's Fracture. Duke Orthopaedics. Cited from textbook online October 2007.
Wheeless' Textbook of Orthopaedics; Monteggia Fractures in Children. Duke Orthopaedics. Cited from textbook online October 2007.
Kakarala G, Simons AW; Forearm fractures. eMedicine. Last Updated July 17, 2007.
Disabella V; Elbow and Forearm Overuse Injuries eMedicine.com 2005

Pathological - Disease Processes

Wednesday, March 18, 2009