Forearm fractures: Monteggia and Galeazzi

Written by the X-Ray Atlas editorial team from the sources listed below · Medical review pending · Updated 24 October 2026 · Level: Intermediate

The radius and ulna are bound together at the elbow, along the interosseous membrane and at the wrist, so the forearm behaves like a ring. Break a ring in one place and it usually breaks, or dislocates, somewhere else too. That is why an apparently isolated fracture of one forearm bone should send you looking for a dislocation at the elbow or the wrist. Missing the dislocation in a Monteggia or Galeazzi injury is a classic and costly error, because late diagnosis makes treatment much harder.

1. The ring principle and the views you need

A forearm series is an AP and a lateral of the whole radius and ulna. The rule is simple: always include, or separately image, the elbow and the wrist. This is the "two joints" part of the rule of twos. A film that cuts off the elbow cannot show a radial head dislocation, and one that cuts off the wrist cannot show a disrupted distal radioulnar joint (DRUJ).

Then check two joints in particular:

• Proximal radioulnar joint / radiocapitellar joint: the radiocapitellar line (along the axis of the radius) should pass through the capitellum on every view. See elbow fractures.
• Distal radioulnar joint: on the PA the radius and ulna should be closely applied, without a widened gap. On a true lateral the ulna should sit in line with the radius, not displaced dorsally or volarly.

2. Monteggia fracture-dislocation

A Monteggia injury is a fracture of the ulna, usually in the proximal third, with dislocation of the radial head. The ulnar fracture is usually obvious. The radial head dislocation is the part that gets missed, especially if the film is centred on the shaft.

Bado classification

Type	Radial head dislocation	Ulnar fracture
I	Anterior (the most common type)	Ulnar shaft, angulated anteriorly
II	Posterior or posterolateral	Ulnar shaft, angulated posteriorly
III	Lateral or anterolateral	Ulnar metaphysis, just below the coronoid (commoner in children)
IV	Anterior	Fractures of both the radius and ulna

The radial head usually dislocates in the direction the ulnar fracture points (the apex of the angulation). In children, the ulnar component may be only a plastic bowing deformity or a greenstick fracture, with no obvious line. A "normal" ulna with a broken radiocapitellar line still means a Monteggia-type injury. See buckle and greenstick fractures.

The posterior interosseous nerve (a branch of the radial nerve) can be injured, so check finger and thumb extension.

3. Galeazzi fracture-dislocation

A Galeazzi injury is a fracture of the radius, typically at the junction of the middle and distal thirds, with dislocation or subluxation of the DRUJ. Signs of DRUJ disruption include:

• widening of the gap between the distal radius and ulna on the PA;
• dorsal (or less often volar) displacement of the ulnar head relative to the radius on a true lateral;
• shortening of the radius relative to the ulna (a change in ulnar variance);
• a fracture at the base of the ulnar styloid.

In adults the radial shaft fracture is usually displaced and managed surgically, and the DRUJ is assessed after fixation. In children the equivalent is sometimes a physeal injury of the distal ulna rather than a true dislocation.

4. Other forearm injuries

• Both-bone fractures: fractures of the radial and ulnar shafts, often at similar levels after high-energy trauma. In adults they are usually fixed surgically, because shortening and rotation impair pronation and supination.
• Nightstick fracture: an isolated fracture of the ulnar shaft from a direct blow, typically when the forearm is raised to defend the head. It is a genuinely isolated injury, but you must still confirm the radial head is in joint on a view that includes the elbow.
• Essex-Lopresti injury: a radial head fracture with tearing of the interosseous membrane and disruption of the DRUJ. The longitudinal stability of the forearm is lost and the radius migrates proximally. Wrist pain in a patient with a radial head fracture is the clue, and it is often missed initially.
• Children: forearm fractures in children are often incomplete. A greenstick fracture breaks one cortex and bends the other, a buckle (torus) fracture bulges the cortex near the distal metaphysis, and plastic bowing bends the bone with no visible line at all. Remodelling potential is high, so more angulation is tolerated than in adults, but the same rule applies: always check the radial head and the DRUJ. A missed paediatric Monteggia injury can leave a chronically dislocated radial head that is difficult to reconstruct months later. See Salter-Harris fractures for injuries that cross the growth plate.
• Distal radius fractures are covered separately: see distal radius fractures.

5. Describing a forearm fracture

Use the standard structure: bone and level (proximal, middle or distal third), pattern (transverse, oblique, spiral, comminuted), displacement of the distal fragment (translation, angulation with the convention stated, shortening, rotation), and then the state of both joints. For example:

Rotation is hard to judge on a film; a mismatch in the width of the bones at the fracture, or a change in the profile of the radial tuberosity and ulnar styloid, can suggest it.

6. Pitfalls

• Not imaging the joints. The single biggest cause of missed Monteggia and Galeazzi injuries.
• A rotated lateral of the elbow can make the radiocapitellar line look abnormal. Check it on more than one view and on a true lateral.
• Plastic bowing in children: no fracture line, just a curved ulna. Compare with the expected straight posterior border of the ulna.
• Calling an isolated ulnar fracture a nightstick injury without checking the elbow.
• Isolated radial head "dislocation" in a child may be congenital (usually posterior, bilateral, with a dome-shaped radial head) rather than traumatic; a traumatic one is a Monteggia variant until proven otherwise.
• Forgetting the DRUJ after a radial head fracture (Essex-Lopresti).

Red flags: act now

What to focus on, by role

Role	Priorities
Medical student	MUGR, the ring principle, and the radiocapitellar line.
Nurse / ENP	Make sure the request covers the elbow and wrist. Check distal neurovascular function and compartment symptoms.
Junior doctor	Check both joints on every forearm film, and examine the wrist in every radial head fracture.
Radiographer	Include both joints on the forearm views or add dedicated elbow and wrist views. Obtain true laterals.
Advanced / FRCR	Bado types, plastic bowing variants in children, Essex-Lopresti and subtle DRUJ subluxation.

Practise on real upper limb X-rays →

References

1. Radiopaedia. Monteggia fracture-dislocation. radiopaedia.org
2. Radiopaedia. Galeazzi fracture-dislocation. radiopaedia.org
3. Bado JL. The Monteggia lesion. Clin Orthop Relat Res 1967;50:71–86.
4. Radiology Masterclass. Fracture description. radiologymasterclass.co.uk
5. Radiology Masterclass. Elbow X-ray gallery. radiologymasterclass.co.uk

For education only. Not a substitute for a formal report, senior review or your local policy. Never use this page to make decisions about a real patient.