Monteggia Fractures

The childhood injury behaves differently enough to be treated separately in Monteggia fractures in children, where closed reduction usually succeeds and the missed radial head is the dominant problem. The mirror-image forearm fracture-dislocation is set out in Galeazzi fractures.

Who. The age distribution is bimodal, with one peak in childhood (4-10 years) and another in middle age (40-60 years). Children predominantly sustain Type I (anterior) injuries and adults predominantly Type II (posterior). Elderly patients often have more comminuted patterns.

Mechanism. The two peaks reflect different mechanisms: children fall with the arm hyperextended (Type I), while adults sustain direct blows or axial loading (Type II).

• Children - falls from height, playground injuries
• Adults - high-energy trauma, sports injuries, direct blows
• Elderly - low-energy falls with osteoporotic bone

The proximal radioulnar joint. The radial head articulates with the radial notch of the ulna and is held there by the annular ligament, a strong fibrous band attached to the anterior and posterior margins of the notch. The ligament forms 4/5 of the fibro-osseous ring around the radial head, is lined with cartilage on its inner surface, and prevents the head migrating during rotation. The quadrate ligament provides a secondary restraint.

The interosseous membrane. It connects the radius and ulna throughout the forearm, its fibres running obliquely from radius to ulna, proximal-lateral to distal-medial. The central band is the thickest and strongest portion. The membrane transmits force from the radius to the ulna, and its disruption leads to proximal migration of the radius.

Why the radial head dislocates. The two bones are linked as a functional unit. The ulna is the fixed bone, stable at the elbow through the olecranon, and the radius rotates around it in pronation and supination. When the ulna angulates, the radial head must dislocate to accommodate it.

The proximal ulna is not straight. It carries a normal dorsally directed (apex-posterior) angulation of roughly 6 degrees, the proximal ulna dorsal angulation (PUDA), located about 5-6 cm distal to the tip of the olecranon, together with a variable proximal radioulnar convergence in the coronal plane. It is a genuine anatomical bow, and the plate has to respect it (see Surgical Technique).

Bado classifies the lesion by the direction of the radial head dislocation and the pattern of the ulnar injury. The frequencies in the table are for adults.

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Type I in more detail. The force is a hyperpronation with hyperextension: a fall on the outstretched hand with the forearm pronated, the biceps pulling the radial head anteriorly. In children the ulna often fails as a greenstick fracture.

Type II in more detail. A direct blow to the posterior aspect of the flexed elbow, or an axial load on it, angulates the ulna posteriorly and drives the radial head posteriorly or posterolaterally.

Jupiter's subdivision of Type II. Jupiter subdivides the posterior lesion, and the subtype helps predict difficulty: proximal fractures near the coronoid (IIA) may require a different approach and have higher complication rates.

Look for forearm deformity, swelling over the proximal forearm, and a radial head prominent laterally or posteriorly.

Feel and move. Palpate the ulnar fracture site and the position of the radial head, and check for tenderness over the DRUJ. Supination and pronation are limited and elbow movement is painful; assess grip strength.

The nerve. The posterior interosseous nerve (PIN) is the nerve most at risk. Test finger extension (EDC, EIP) and thumb extension (EPL) specifically. Wrist extension is usually preserved, because ECRL and ECRB are innervated proximal to the PIN. The incidence, prognosis and management of the palsy are set out under Complications.

Radiographs. Image the whole forearm and the elbow in its own right:

• AP and lateral forearm, which must include the elbow and wrist joints
• AP and lateral elbow, to confirm the relationship of the radial head
• Contralateral comparison if ulnar length is questionable

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The radiocapitellar line. A line drawn through the centre of the radial shaft and head must pass through the centre of the capitellum on every view: AP, lateral and oblique. If it does not, the radial head is subluxed or dislocated.

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CT is indicated for assessing a coronoid fracture, for complex proximal ulna fractures, and in chronic Monteggia to assess changes in the shape of the radial head.

MRI is rarely indicated. It has a place where interosseous membrane disruption (the Essex-Lopresti variant) is suspected, for assessing cartilage integrity in chronic injuries, and for planning where soft tissue is interposed.

The principle. Fix the ulna anatomically, restoring its length and alignment, and in an acute injury the radial head typically reduces spontaneously. If it does not, suspect interposed tissue: the annular ligament, capsule or biceps.

Acute or chronic. The dividing line is 4 weeks. An injury presenting later, missed or delayed, is chronic and is reconstructed. Treatment principles also differ significantly between adults and children.

Algorithm

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Acute Type I/IIAdult Type IIType III/IV ComplexChronic MonteggiaPaediatric Special Considerations

An anterior (Type I) or posterior (Type II) radial head dislocation presenting within 4 weeks of injury is the most common scenario in both children and adults. After a closed reduction attempt (see the timeline under Surgical Technique):

1. Anatomic ulnar ORIF, restoring length and alignment; compare with the contralateral side for length
2. Intraoperative fluoroscopy to confirm the radiocapitellar line
3. The radial head reduces spontaneously in 95% of cases; if it does not, explore for interposed tissue

The associated injuries decide the result. In Ring's adult series about two-thirds of Bado Type II fractures had an associated radial head fracture, and many also had a coronoid fracture; the majority of the poor results were Type II lesions with these associated injuries. The ulnar shaft heals reliably. It is the radial head and coronoid that determine elbow stability and function.

An elbow fracture-dislocation. Bado II sits on a spectrum with the posterior olecranon fracture-dislocation. The injury is centred on the proximal ulna and the ulnohumeral and radiocapitellar articulations, so the coronoid (the anterior buttress against posterior instability) and the radial head (the lateral buttress) must both be restored, not just the ulnar shaft.

Plan for them at the index operation. Fix or replace the radial head and address the coronoid (its classification and fixation are covered in Coronoid Fractures). Coronoid access from the standard posterior approach is difficult, and a tenuous coronoid reduction predicts a poor result (Xiao 2021). Under-treating these injuries is why adult Type II outcomes lag behind Type I and paediatric injuries.

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Types III and IV are more complex patterns that need an individualised approach. Both bones may need fixation, and the radial head may need direct open reduction, ORIF or replacement; consider temporary K-wire stabilisation. The risk of complications is higher, elbow stiffness is more frequent and rehabilitation takes longer.

Essex-Lopresti. A radial head fracture with interosseous membrane disruption and DRUJ injury: a rare but devastating combination that can occur with Type IV. Suspect it with tenderness along the entire interosseous space, DRUJ instability on examination or positive ulnar variance on the radiograph. It changes management: the radial head cannot be excised, because the radius would migrate proximally; DRUJ stability must be addressed; and radial head replacement is considered if the head is unfixable.

Don't Miss Essex-Lopresti

In Type IV, with both bones fractured, specifically examine the DRUJ and the entire interosseous membrane. Missing an Essex-Lopresti injury leads to proximal radial migration, chronic wrist pain and poor outcomes.

More than 4 weeks. A missed or delayed presentation. Outcomes are significantly worse than after acute treatment, and results deteriorate rapidly with delay, which is why early diagnosis is critical.

The difficulties of the chronic injury:

• Radial head deformity and overgrowth from chronic dislocation
• Annular ligament scarring, deficiency or absence
• Adaptive changes in the capitellum
• Limited remodelling in adults

The reconstruction proceeds in order:

1. Ulnar osteotomy to restore length and correct angular deformity
2. Open reduction of the radial head via a Kocher approach
3. Annular ligament reconstruction (Bell Tawse technique)
4. Consider a temporary transarticular K-wire (3-4 weeks)

In adults, after skeletal maturity, radial head excision is the alternative (see Surgical Technique).

Is ligament reconstruction always needed? The classic teaching is that it is. The algorithm above reserves annular ligament repair or reconstruction for the radial head that is unstable after osteotomy and open reduction, and the modern paediatric series behind that position are set out under Controversies.

Results. Good results in 70-80% of paediatric cases. Adult outcomes are less predictable (see Outcomes), results decline with increasing delay from injury, and additional procedures may be required for stiffness.

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Most common type

Adult

Type II (posterior)

Paediatric

Type I (anterior)

Ulna pattern

Adult

Complete fracture

Paediatric

Often greenstick/plastic

Treatment

Adult

Operative fixation standard

Paediatric

Closed reduction may succeed

Annular ligament

Adult

Often ruptured

Paediatric

Often intact

Chronic reconstruction

Adult

Poor outcomes

Paediatric

Better remodelling potential

Adult vs Paediatric Monteggia

Feature	Adult	Paediatric
Most common type	Type II (posterior)	Type I (anterior)
Ulna pattern	Complete fracture	Often greenstick/plastic
Treatment	Operative fixation standard	Closed reduction may succeed
Annular ligament	Often ruptured	Often intact
Chronic reconstruction	Poor outcomes	Better remodelling potential

Closed reduction. In a child it may succeed if the injury is truly acute:

• General anaesthesia for muscle relaxation
• Correct the ulnar angulation first
• Confirm the radiocapitellar line is restored
• Long arm cast in supination (Type I) for 4-6 weeks
• Close follow-up for re-displacement

Operate for any of these:

• Failed closed reduction
• Re-displacement after closed treatment
• Chronic injury (over 3-4 weeks)
• Open fracture
• Neurovascular compromise

Clinical Pearl

Paediatric Monteggia can be treated closed if truly acute (under 1 week), greenstick pattern, and radial head reduces concentrically. All others require operative fixation.

The decision table below summarises the tabs.

Nerve injury. The PIN is injured by stretch as the radial head dislocates, or by direct compression, and the association is strongest with Bado Type III. Most palsies recover spontaneously by 3-4 months; if there is no clinical recovery, obtain an EMG at 6 weeks. Explore the nerve for:

• No recovery by 3-4 months
• An open fracture with suspected nerve injury
• Worsening after closed reduction

Stiffness. Prevention is early motion, stable fixation, avoiding prolonged immobilisation, and aggressive physiotherapy from week 2. For established contracture, static progressive splinting (low-load, prolonged stretch) is more effective than dynamic splinting. If therapy reaches a plateau, consider open or arthroscopic capsular release at 6-12 months.

Heterotopic ossification. Prophylaxis for a patient with prior HO is indomethacin or radiation. Established heterotopic bone is resected when mature, at 12-18 months.

Principles. Move early if fixation is stable. Avoid forced supination for the first 4 weeks, which protects the annular ligament, and protect against varus stress if the LCL has been repaired. Rehabilitation works on forearm rotation as well as elbow flexion and extension.

Return to activities is staged:

• Desk work: 2-4 weeks
• Manual labour: 3-6 months
• Contact sports: 6 months minimum
• Full unrestricted activity: when strength and range of motion have normalised

The ranges in this section are conventional teaching estimates unless a cited series is named; the verified outcome data on this page are Ring 1998 (83% good/excellent in 48 adults), Zheng 2020 (75% congruent at 19 months in missed paediatric cases) and Zilliacus 2024 (all 60 followed children with full motion).

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What predicts a good result. An acute injury (under 4 weeks), an anatomic ulnar reduction, stable fixation, early mobilisation and a Type I or II pattern. Children have better outcomes overall because of their remodelling potential; adults require an anatomic reduction for a good outcome.

What predicts a poor one. A chronic injury (over 4 weeks), a comminuted proximal ulna, an associated coronoid fracture, a PIN palsy that is not recovering, a Type III or IV pattern, and an open wound.

The long term. After acute anatomic fixation, ulnar union and a stable, concentrically reduced radial head are the expectation, with most forearm rotation recovered. Mild residual extension loss is common and rarely functionally limiting; heterotopic ossification and persistent PIN weakness are uncommon. Even malalignment is salvageable: re-fixation in Ring's series of 17 malaligned posterior injuries achieved union and a concentric ulnohumeral reduction in all of them. But 9 of those 17 had radiographic ulnohumeral arthrosis at a mean of 59 months, and late degeneration is the honest long-term caveat.

Related pages: Monteggia and Galeazzi Fractures sets the two forearm fracture-dislocations side by side if you want the comparison rather than this depth; Monteggia Fractures in Children and Paediatric Forearm Fractures for the plastically deformed ulna that hides the injury; Galeazzi Fractures for the mirror-image lesion at the wrist. For the injuries that decide a Bado II outcome see Coronoid Fractures and Radial Head Fractures, with Olecranon Fractures for the proximal ulna differential, Radial Head Dislocations for the isolated and congenital mimics, and Radioulnar Synostosis for the complication that costs rotation.

Routine annular ligament reconstruction? In chronic paediatric cases, ulnar osteotomy with indirect reduction can stabilise the radial head without formal reconstruction (Song 2012). When the annular ligament is addressed, repair of the native ligament outperformed reconstruction (Zheng 2020). Many now reserve formal Bell Tawse reconstruction for cases that remain unstable intra-operatively.

Open or indirect (ulna-based) reduction in chronic cases. Whether to open the radiocapitellar joint or rely on over-correction of the ulna (angulation-translation osteotomy) remains debated. Both can succeed, and the choice is often driven by chronicity, radial head shape and intra-operative stability.

The temporary transarticular K-wire. Trans-capitellar or transarticular K-wires can hold a reduced radial head but carry a real risk of wire breakage and migration. Use is selective, kept short, and avoided where stable fixation alone is sufficient.

Managing the PIN palsy. Most PIN palsies are neurapraxic and recover, so early exploration is generally not indicated. The grey zone is the new, complete post-reduction palsy where nerve entrapment cannot be excluded; the timing of exploration and the role of early EMG or nerve ultrasound are not standardised.