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Ulnar and Radial Shaft Fractures
Description
In adults, fractures of the shaft (diaphysis) of the ulna and radius are most often the consequence
of a direct blow to the forearm or other high energy mechanisms. In the adult, these injuries
usually require surgical fixation. By contrast, so-called "both bone" fractures in the pediatric
population result from simple falls and other lower energy mechanisms. In children, ulnar and
radial shaft fractures are amenable to casting. Imperfect healing can lead to loss of pronation and
supination of the hand.
Structure and function
The human forearm is comprised of two bones: the ulna, medially, and the radius,
laterally. Bridging the ulna and radius is an interosseous membrane that transmits forces from
ulna to radius and vice versa. The forearm flexes and extends at the elbow, with the articulation
of the ulna with humerus at the trochlear notch. The head of the radius also articulates with the
humerus at the capitellum, allowing the forearm to pronate and supinate. Pronation and
supination also require an intact distal radial ulnar joint.
normal radial/ulnar shaft anatomy on plain xray
The median, ulnar, and radial nerves course along the forearm, along with the radial and
ulnar arteries. The ulnar and radial nerves are located most medially and laterally, respectively,
thus they are most susceptible to damage with fracture of the shaft of their adjacent bones.
The extrinsic muscles of the hand originate in the forearm (and elbow) and therefore forearm
fractures, if not treated properly, can also lead to hand dysfunction.
The course of the muscles, likewise, may create deforming forces on the injured bones: for
example, the flexor muscles of the fingers and wrist tend to produce dorsal bowing of the radius
and ulna, by flexing distal fragments.
Patient presentation
Patients with fractures of the shaft of the ulna and radius present following trauma with pain in
the forearm, and at times with gross deformity.
Radiographs allow full characterization of the injury. Care must be taken to fully visualize the
wrist and elbow joints.
Pediatric both-bone fractures can be complete (involving a complete break of both bones) or socalled “greenstick”, involving an incomplete break of either the ulna or radius, or both. This
configuration occurs in children because pediatric bones tend to be softer and are more prone to
break incompletely (much like the branches of a growing tree, hence the name) compared to
mature adult bones.
A radial shaft fracture with distal radial ulnar joint (DRUJ) instability is referred to as a Galeazzi
fracture. A patient with a Galeazzi fracture will present not only with pain in the forearm where
the bone is broken, but also swelling, tenderness, and pain at the wrist. T
Ulnar shaft fractures are most often caused by a direct blow to the border of the ulna on the
medial forearm. It can occur when the ulnar border is exposed, such as upon raising the arm in
defense (a so-called “night stick fracture”). The patient will usually experience pain, and show
signs of point tenderness in the ulnar region of the forearm. Swelling will likely be present in the
forearm.
Monteggia fractures are injuries to the proximal one-third of the ulna associated with a
dislocation of the head of the radius. It is rare for a fracture to the proximal one-third of the ulna
to occur alone. As a result, it is always imperative to do a full work-up of both the ulna and
radius to assess whether the radius, especially the radial head, is injured. Most Monteggia
fractures of the ulna are associated with anterior dislocation of the radial head.
Damage to the posterior interosseous nerve may occur with a Monteggia fracture; it is therefore
important to assess the function of the posterior interosseous nerve, which, for example, can be
accomplished by checking the patient’s ability to extend the hand at the wrist.
Figure: xrays of Galeazzi fracture,
Figure: xrays ofMonteggia fracture,
Figure: xrays ofgreenstick fracture
Clinical evidence
Patients with forearm fractures should have the following information collected and documented:
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status of the skin and soft tissues
range of motion of the wrist and elbow
gross alignment of the limb
congruity of the elbow and wrist joints on xray
status of nerves: radial (including posterior interosseous), median (including anterior
interosseous), and ulnar
perfusion status of hand
figures: demonstrating normal AIN and abnormal AIN function (right). In the figure at the right,
the IP joint of the thumb and the DIP joint of the index finger will not flex normally when the
AIN is injured. Thus, the patient cannot make an "OK" sign
Epidemiology
Fractures of the ulnar and radial shaft can occur across all age groups, but are most common in
children. Indeed, mid-shaft forearm fractures are among the most common type of fracture in
children. This type of injury is most often the consequence of direct trauma, frequently from a
fall on an outstretched hand from a large height.
Other populations at risk are adults or children involved in events such as traffic accidents and
sports injuries, commonly from mountain biking and skating. Osteoporosis, occurring mostly in
postmenopausal women, is commonly associated with forearm fractures, although they most
often occur in the distal forearm in this population.
Differential diagnosis
A forearm shaft fracture should be readily diagnosed from radiography. As such, there is no
"differential" diagnosis list, per se; the question is either about what other injuries may be
present, or whether the fracture was caused by some underlying abnormality.
Such secondary injuries with Monteggia fractures can include possible olecranon fracturedislocation, radial head or coronoid fractures, or lateral collateral ligament injury.
Secondary injuries include not only damage to the elbow or wrist, but more distal, otherwise
unrelated, injuries simply sustained at the same time.
Osteoporosis should be considered if the mechanism of injury suggests particularly low energy.
Fractures through a pre-existing lesion (e.g., giant cell tumor of Paget's disease) are rare but
possible.
Red flags
Radiographs that are inadequately broad, i.e. do not visualize the elbow and wrist are an
invitation to trouble.
Both bone fractures can be complicated by acute compartment syndrome of the forearm, which
is rare but possible. Signs suggesting compartment syndrome are pain on extension of digits and
marked edema. The phrase “pain out of proportion to the injury” is difficult to apply when there
is a broken bone, but in general, immobilizing a fracture should reduce the patient’s distress; if it
does not, compartment syndrome should be explicitly ruled out.
Pediatric both-bone fractures, though commonly seen after accidental trauma, may also be the
product of child abuse. Careful attention should be paid to the history given by the parents,
(obtained from each separately, if abuse is suspected).
Pediatric both-bone fractures can at times be open fractures, as the edges of the fracture may
penetrate the skin.
Treatment options and outcomes
Displaced and unstable fractures ulnar should be treated operatively. Even non-displaced radial
fractures usually are treated with surgery.
Monteggia fractures require open reduction and internal fixation of the ulnar shaft fracture. If
this procedure fails to reduce the radial head, then that too must be opened and reduced.
xray: ORIF of both bone fx
Most fractures heal if adequately reduced.
Even subtle malalignment can impede pronation and supination.
Most cases of neuropathy (in the absence of compartment syndrome) tend to resolve.
Risk factors and prevention
Beyond giving trite advice (“Don’t drink and drive. Stay out of fights. Don’t fall.”) there is not
much physicians can do to prevent these injuries. The key “prevention” step is to prevent
complications by not missing associated injuries at the time of initial presentation.
Miscellany
Although two fractures of the forearm are named after Italian surgeons from Milan, their
contributions did not reflect a golden age of orthopaedic surgery in that city. In fact, they were
not contemporaries: Giovanni Battista Monteggia died in 1815, more than a half-century before
Ricardo Galeazzi was born in 1866.
Key terms
Galeazzi fracture, Monteggia fracture
Skills
Recognize and describe fracture patterns on plain radiographs; assess the neurological function
with a patient following fracture; predict the deforming forces that muscles will exert on
fractures.