Trauma 101: Orthopedics Study Tool

Monteggia Fracture-Dislocation

Forearm2 management options6 viva pearls

Classification systems

AO/OTA grouping for the forearm segment

Mechanism

A fall onto the outstretched hand with forced pronation, or a direct blow to the posterior forearm as in a defensive injury, fractures the ulna and forces the radial head out of its relationship with the capitellum. The essential concept is that an ulnar shaft fracture with any angulation must displace the radial head, because the two bones are tethered by the interosseous membrane and the annular ligament.

Age considerations

Paediatric: Often a plastic deformation or greenstick ulnar injury with a subtle radial head dislocation that is easily missed; the dislocation is the injury that matters. Correcting the ulnar bow reduces the radial head, usually closed. A missed injury presenting late is a difficult reconstruction with ulnar osteotomy and annular ligament reconstruction.
Young adult: Adult patterns need anatomical rigid ulnar fixation; the radial head then reduces in most cases. Associated radial head and coronoid fractures are common in the posterior type and must be addressed.
Elderly: Osteoporotic comminuted posterior patterns behave badly; expect to plate the ulna with a longer construct and to consider radial head replacement if the head is unreconstructable.

Management options

Closed reduction and cast (paediatric)show

Indication

Paediatric plastic deformation or greenstick ulnar injuries where restoring ulnar length and bow reduces the radial head and the reduction is stable.

Implant design notes

No implant. Above-elbow cast in a position that keeps the radial head reduced — flexion and supination for the anterior type.

Approach

Non-operative, under anaesthesia with fluoroscopic confirmation.

Steps overview

Confirm the diagnosis by drawing the radiocapitellar line on both views — it must pass through the capitellum in every position
Under anaesthesia, correct the ulnar bow by direct pressure and traction
Reduce the radial head with the elbow flexed and the forearm supinated for the anterior type
Confirm concentric radiocapitellar reduction fluoroscopically through an arc of motion
Apply an above-elbow cast in the stable position for about four to six weeks
Radiograph weekly for the first fortnight — late redislocation is the pitfall

Notes

If the ulna cannot be held out to length, the radial head will not stay reduced; fix the ulna rather than accepting a marginal cast reduction.

Resident summary compiled from standard orthopaedic trauma teaching; verify against your departmental protocol.

Ulnar fixation with reduction of the radial headshow

Indication

All adult Monteggia injuries, and paediatric injuries with an unstable or irreducible ulnar fracture.

Implant design notes

Plate applied to the ulna along its subcutaneous or dorsal border, restoring exact length and bow — the plate must not leave the ulna short or angulated, because either error leaves the radial head subluxed. Locking constructs help in osteoporotic bone and in comminuted proximal patterns; a pre-contoured proximal ulna plate is used for very proximal fractures.

Approach

Direct approach along the subcutaneous border of the ulna, extended proximally as a posterior elbow approach when the coronoid or radial head needs attention.

Steps overview

Position supine with the arm across the chest or on a hand table; tourniquet and fluoroscopy
Expose the ulnar fracture along its border, preserving soft tissue attachments
Reduce the ulna anatomically, paying particular attention to restoring length and the normal bow
Apply the plate with adequate fixation proximal and distal, lagging simple oblique patterns
Assess the radiocapitellar relationship fluoroscopically through a full arc of motion and rotation
If the radial head remains subluxed, re-inspect the ulnar reduction before blaming the ligament
Address a radial head or coronoid fracture and repair the lateral collateral complex if needed
Close and begin early protected motion, avoiding the provocative position

Notes

The single commonest cause of a persistently subluxed radial head after surgery is imperfect ulnar reduction — go back to the ulna first. Only then consider annular ligament pathology.

Resident summary compiled from standard orthopaedic trauma teaching; verify against your departmental protocol.

Viva pearls

Say the principle out loud: an ulnar shaft fracture with angulation cannot exist without radial head displacement — so always draw the radiocapitellar line.
The radiocapitellar line must pass through the capitellum on every view and in every position; a single view is not enough.
The commonest reason a Monteggia is missed is that the observer sees the obvious ulnar fracture and never looks at the elbow.
If the radial head will not stay reduced after ulnar plating, the ulna is malreduced — usually short or with a lost bow.
Posterior interosseous nerve palsy can accompany the injury and usually recovers once the radial head is reduced.
A neglected paediatric Monteggia needs ulnar osteotomy with lengthening and often annular ligament reconstruction — a much bigger operation than early recognition.

Sources for further reading

Rockwood and Green's Fractures in Adults — Monteggia injuries
Rockwood and Wilkins' Fractures in Children — Monteggia lesions in children
Standard operative orthopaedics textbook — forearm fracture-dislocations

My labelled images · 0

Attach your own teaching radiographs with your own labels for pattern-recognition practice. Use anonymised study images only — never anything patient-identifiable.

No images yet for this topic.

Resident-authored study summary in original wording, not reproduced from copyrighted source text.