Pediatric | O'Brien Classification | Reduction Techniques
O'BRIEN CLASSIFICATION (By Angulation)
Critical Must-Knows
- Less than 30° angulation = no reduction needed in children less than 10 years
- Less than 45° angulation = acceptable in children over 10 years
- Closed reduction techniques: supination and valgus, Israeli technique (thumb pressure)
- Patterson technique: percutaneous K-wire joystick reduction
- Avoid open reduction if possible - high rate of stiffness and AVN
Clinical Pearls
- "Radial head does not appear until age 3-5, neck fractures more common in children
- "Posterior interosseous nerve (PIN) at risk - assess finger/thumb extension
- "Open reduction associated with higher complication rates
- "Metaizeau technique: ESIN reduction without opening
Critical Exam Concepts
Reduction Threshold
Less than 30° angulation = No reduction needed. Aim for less than 30° in young children, less than 45° in adolescents. The radial head has significant remodeling potential.
Avoid Open Reduction
Open reduction has higher complications. Associated with stiffness, AVN, radioulnar synostosis. Try closed, then percutaneous, then intramedullary (Metaizeau) before opening.
PIN Injury
Posterior interosseous nerve at risk. Assess finger and thumb extension before and after any intervention. Usually neurapraxia. Watch for iatrogenic injury during percutaneous methods.
Mechanism
Valgus force with axial load. Fall on outstretched hand with elbow extended. Associated with Monteggia variants and elbow dislocation in 10% of cases.
Quick Decision Guide by Angulation
| Angulation | Classification | Management |
|---|---|---|
| Less than 30° | O'Brien Type I | Non-operative - cast |
| 30-45° | O'Brien Type II | Closed reduction attempted |
| 45-60° | O'Brien Type II-III | Closed or percutaneous reduction |
| Greater than 60° | O'Brien Type III-IV | Percutaneous/Metaizeau/consider open |
30-45Angulation Thresholds
| 3 | 30° younger children Less than 10 years: accept up to 30° |
| 0 | 0 intervention if less than threshold No reduction needed below threshold |
| 4 | 45° older children Over 10 years: accept up to 45° |
| 5 | 5 degrees less remodeling per year Older = less remodeling = stricter criteria |
| 3 | 30° younger children Less than 10 years: accept up to 30° | 4 | 45° older children Over 10 years: accept up to 45° |
| 0 | 0 intervention if less than threshold No reduction needed below threshold | 5 | 5 degrees less remodeling per year Older = less remodeling = stricter criteria |
Hook:30 for young, 45 for old - both end in fives!
CIPOMReduction Escalation
| C | Closed reduction Supination, valgus, thumb pressure |
| I | Israeli technique Direct pressure on radial head |
| P | Percutaneous K-wire Patterson joystick technique |
| O | Open reduction Last resort - higher complications |
| M | Metaizeau technique ESIN reduction without opening |
| C | Closed reduction Supination, valgus, thumb pressure | O | Open reduction Last resort - higher complications |
| I | Israeli technique Direct pressure on radial head | M | Metaizeau technique ESIN reduction without opening |
| P | Percutaneous K-wire Patterson joystick technique |
Hook:Escalate systematically - avoid open if possible!
SASAComplications of Open Reduction
| S | Stiffness Loss of pronation/supination most common |
| A | AVN Avascular necrosis of radial head |
| S | Synostosis Radioulnar synostosis |
| A | Arthritis Post-traumatic radiohumeral arthritis |
| S | Stiffness Loss of pronation/supination most common | S | Synostosis Radioulnar synostosis |
| A | AVN Avascular necrosis of radial head | A | Arthritis Post-traumatic radiohumeral arthritis |
Hook:SASA remember why to avoid open!
Overview and Epidemiology
Why Neck Not Head?
In children, the radial head is largely cartilaginous and the neck is weaker. Force transmission causes neck fractures rather than head fractures seen in adults. The radial head ossification center appears at age 3-5 years.
Epidemiology
- 5-10% of pediatric elbow fractures
- Peak age 9-10 years
- Equal male to female ratio
- Usually falls (playground, sports)
- Associated injuries common (50%)
Associations
- Elbow dislocation (10%)
- Olecranon fractures
- Ulna fractures (Monteggia variant)
- Medial epicondyle fractures
- Capitellum injuries
Anatomy and Biomechanics
Critical Anatomy
The posterior interosseous nerve (PIN) runs anteriorly around the radial neck. At risk during injury and during percutaneous/open procedures. Enters supinator at arcade of Frohse. Assess finger and thumb extension.
Radial Head Vascularity
Blood supply: Primarily through periosteal vessels around the neck. Intramedullary flow minimal.
AVN risk: Disruption of periosteal vessels during open reduction can cause AVN. Preserve soft tissues if surgery needed.
Remodeling: Excellent potential in children due to physis contribution to growth and robust blood supply.
Classification Systems
O'Brien Classification (By Angulation)
| Type | Angulation | Treatment |
|---|---|---|
| Type I | Less than 30° | Non-operative |
| Type II | 30-60° | Closed reduction |
| Type III | Greater than 60° | Percutaneous or open reduction |
| Type IV | 90° (complete displacement) | Usually requires open reduction |
Key point: Angulation measured from shaft axis on lateral X-ray.
Clinical Assessment
History
- Fall on outstretched hand
- Valgus mechanism
- Lateral elbow pain
- Difficulty with rotation
- Associated dislocation
Examination
- Lateral elbow tenderness
- Swelling radiocapitellar region
- Limited pronation/supination
- PIN function (finger/thumb extension)
- Elbow stability
PIN Assessment
Test BEFORE any intervention. Ask child to extend fingers at MCPs and thumb at IP joint. Compare to other side. PIN injury presents as weak or absent extension. Usually neurapraxia with complete recovery.
Associated Injuries
50% have associated elbow injuries. Check for olecranon fracture, medial epicondyle fracture, elbow dislocation. Monteggia variant may have associated radial neck injury.
Investigations
X-ray Protocol
Standard views: AP and lateral elbow.
Measurements: Angulation on lateral view - angle between radial shaft and head/neck line.
Associated injuries: Check for elbow dislocation, ulna fracture, olecranon fracture.
Differential Diagnosis
The painful, swollen, rotation-restricted child's elbow has several mimics. The radiocapitellar line and the radial neck angle on a true lateral are the discriminators that separate these on plain film.
Distinguishing the Lateral Paediatric Elbow Injury
| Diagnosis | Key clinical clue | Radiographic discriminator | Why it matters |
|---|---|---|---|
| Radial neck fracture | Lateral tenderness, painful pronation/supination | Angulation/translation of head on neck; radiocapitellar line intact through head | Remodels well; reduction only if over threshold |
| Radial head subluxation (pulled elbow) | Toddler, axial traction history, arm held pronated, no swelling | Normal radiographs (often reduced by positioning for the film) | No fracture; supination-flexion manoeuvre cures it, do not over-investigate |
| Monteggia / Monteggia-equivalent | Ulnar deformity or tenderness with elbow injury | Radiocapitellar line does NOT pass through capitellum; ulna bowed or fractured | Missed dislocation if you fixate on the radius; reduce the ulna first |
| Lateral condyle fracture | Lateral tenderness, fat pad sign | Metaphyseal fragment lateral distal humerus, NOT radial neck | Intra-articular, Salter-Harris IV, often needs fixation; high non-union risk if missed |
| Capitellum (osteochondral) injury | Mechanical block, effusion in older child | Defect or loose body at capitellum; radial head intact | Different operative plan; MRI often needed |
| Congenital radial head dislocation | Painless, chronic, often bilateral, found incidentally | Dome-shaped/hypoplastic radial head, convex articular surface, no acute fracture line | Do not attempt acute reduction of a chronic/congenital head |
The two not-to-miss errors
Always trace the radiocapitellar line on EVERY paediatric elbow film: a line through the centre of the radial neck must point at the capitellum in all views. If it does not, you are looking at a Monteggia-equivalent, not an isolated radial neck fracture. Second, a normal-looking film in a toddler with a classic traction history is a pulled elbow, not an occult fracture.
Management
Key Principle
Avoid open reduction if possible. Open reduction has significantly higher rates of stiffness, AVN, and synostosis. Escalate through closed, then percutaneous, then intramedullary techniques before considering open.
Non-Operative Management
Indications: Angulation less than 30° in younger children (under 10 years). Angulation less than 45° in adolescents. Stable elbow.
Protocol: Above-elbow cast or splint for 2-3 weeks. Early ROM exercises after. Full activity at 6 weeks.
Outcomes: Excellent. These fractures remodel well.
Reduction Escalation
Escalate systematically. Closed reduction first (supination-valgus, Israeli). If failed, percutaneous K-wire (Patterson). If failed, Metaizeau ESIN. Open only as last resort due to complications.
Surgical Technique Considerations
Percutaneous K-Wire Reduction
Setup: Patient supine. Fluoroscopy. Sedation or GA.
Approach: Insert 1.5-2mm K-wire from lateral side into fracture site adjacent to tilted radial head.
Reduction: Use wire as joystick. Lever angulated head back into position while applying gentle supination.
Post-reduction: Above-elbow cast. Wire removed at 2-3 weeks.
Complications
Complications of Radial Neck Fractures
| Complication | Incidence | Management |
|---|---|---|
| Loss of ROM | 20-50% | Usually pronation/supination. Most improve with time. |
| PIN injury | 5-10% | Usually neurapraxia. Observe. Most recover. |
| AVN radial head | 5-10% | Related to open reduction. May need excision if symptomatic. |
| Radioulnar synostosis | Rare | Cross-union. May need excision. |
| Malunion | Variable | Accept some angulation. Remodeling helps. |
| Heterotopic ossification | Rare | May limit motion. Excise if mature and symptomatic. |
Open Reduction Complications
Open reduction has 2-3x higher complication rates. Stiffness rates up to 50% with open vs 10-20% with closed. AVN and synostosis almost exclusively with open procedures. This is why escalation through closed techniques is so important.
Postoperative Care
Post-Treatment Protocol
Above-elbow cast or splint. Elbow at 90°. Neutral forearm rotation. Non-weight bearing.
Remove cast. Begin active ROM - focus on pronation/supination. Avoid passive stretching.
Progressive strengthening. Return to light activities. Avoid contact sports.
Full return to sports. Monitor for late stiffness. Some ROM loss may persist but often not functional.
Outcomes and Prognosis
Prognosis by Treatment
Non-operative (less than 30°): Excellent prognosis. Full ROM expected. Complete remodeling.
Successful closed reduction: Good outcomes. Some minor ROM loss common but rarely functional.
Percutaneous/Metaizeau: Intermediate outcomes. Better than open reduction.
Open reduction: Higher complication rates. Significant stiffness in up to 50%. AVN risk.
Special Considerations
Radial Neck with Elbow Dislocation
Frequency: 10% of radial neck fractures associated with dislocation.
Priority: Reduce dislocation first. Assess radial head position after.
Management: May need fixation if radial head unstable after dislocation reduced.
Evidence Base and Key Studies
How to read this evidence
There are no randomised controlled trials in paediatric radial neck fractures. The literature is built on retrospective series, a systematic review/meta-analysis, and the original technique-describing papers. The consistent signal across all of them: closed/intramedullary reduction outperforms open reduction, and open surgery is the strongest independent predictor of a poor functional result. O'Brien (1965) and Judet (1962) are the classic classification papers and predate PubMed indexing — they are cited here as historical primary sources without a PMID.
Conservative Treatment: Long-Term Results and Remodeling
- 38 children with displaced radial neck fractures reviewed 2-20 years after injury
- Radial head deformity present in 83%, but functional disorder in only 11% (4 children)
- All conservatively treated fractures with angulation up to 50° corrected spontaneously
- Functional problems clustered in children treated with open reduction or with secondary growth disturbance (one radioulnar synostosis)
Centromedullary (ESIN/Metaizeau) Pinning — Technique by the Originator
- Describes the leverage/derotation manoeuvre using a single retrograde elastic nail to reduce and stabilise the displaced epiphysis
- Achieves complete reduction without opening the radiocapitellar joint
- The nail is left in situ to stabilise the epiphysis and prevent secondary displacement
- Reported very low complication rate vs open reduction (AVN, intra-articular calcification, stiffness)
Systematic Review & Meta-analysis of Severely Displaced Fractures
- 14 studies, 173 patients with fractures displaced over 60°
- Overall success rate 87% (95% CI 82-92%)
- Closed reduction methods: 90% success (95% CI 85-95%)
- Open reduction methods: 77% success (95% CI 63-89%)
Risk Factors for Poor Outcome in 101 Operated Children
- 101 surgically treated children, minimum 3-year follow-up, satisfactory outcome 65.3%
- Judet type IV (OR 5.78) and open surgical method (OR 12.68) were the only independent predictors of unsatisfactory outcome
- Post-operative radial/PIN nerve palsy in 14.9%, radial head osteonecrosis in 4.0%
- Closed reduction with intramedullary fixation recommended as primary treatment for Judet III-IV
Métaizeau ESIN vs Open Reduction (Judet IV)
- 47 children with Judet type IV fractures: 22 Métaizeau ESIN vs 25 open reduction + K-wire
- Mean Mayo Elbow Performance Score 95.2 (ESIN) vs 88 (open)
- ESIN: 68% excellent, 31% good, no fair/poor results
- Open: 36% excellent, 48% good, 16% fair, with a higher complication profile
Closed ESIN vs Open K-wire (O'Brien Type III)
- 31 children with O'Brien type III fractures: 18 closed ESIN vs 13 open + K-wire
- Métaizeau grading excellent/good: 18/18 closed vs 8/13 open (significant, P=0.001)
- Re-displacement after implant removal in 4 open cases, none in the closed group
- No avascular necrosis in either group at 1-2 year follow-up
Exam Viva Scenarios
Use these scenarios to practise clinical reasoning and management decisions
Scenario 1: Moderately Angulated Radial Neck
"A 9-year-old girl falls on an outstretched hand. X-ray shows a radial neck fracture with 40° angulation. Finger and thumb extension are normal. How would you manage this?"
Scenario 2: Severely Angulated Radial Neck
"An 8-year-old boy has a radial neck fracture with 70° angulation and moderate translation. Closed reduction under sedation failed to improve angulation beyond 50°. What are your next steps?"
Scenario 3: PIN Injury After Reduction
"You perform closed reduction of a radial neck fracture. Post-reduction, the child cannot extend their fingers at the MCPs or their thumb at the IP joint. What is your assessment and management?"
MCQ Practice Points
Angulation Threshold Question
Q: What angulation threshold is acceptable for non-operative management in a 7-year-old? A: Less than 30°. Younger children have greater remodeling potential. Older children (over 10) = 45° threshold.
Nerve at Risk Question
Q: Which nerve is at risk in radial neck fractures? A: Posterior interosseous nerve (PIN). Motor branch of radial nerve. Test finger and thumb extension.
Reduction Technique Question
Q: What technique uses a K-wire as a joystick for radial neck reduction? A: Patterson technique. Percutaneous K-wire inserted adjacent to radial head, used to lever head into position.
Complication Question
Q: Why should open reduction be avoided in radial neck fractures? A: Higher complication rates. Stiffness (up to 50%), AVN, and radioulnar synostosis all more common with open reduction.
Classification Question
Q: What is O'Brien Type III radial neck fracture? A: Greater than 60° angulation. Usually requires percutaneous or open reduction.
Metaizeau Question
Q: What is the Metaizeau technique? A: ESIN reduction. Flexible nail inserted through distal radius, used to lever radial head from below without opening.
Controversies and Areas of Uncertainty
What angle truly needs reducing?
The classic teaching of 30° (young) / 45° (older) is a convention, not trial-derived. Vocke and Von Laer documented spontaneous correction of angulation up to 50° in conservatively treated children, prompting some surgeons to accept higher residual angulation in patients with substantial remodelling potential. There is no consensus threshold and no randomised data to anchor it.
Translation vs angulation
Most thresholds quote angulation, but translation (the Judet axis) may matter as much. A markedly translated but only moderately angulated head can still impede rotation. Decisions should integrate both, plus the child's age and remaining growth.
Leave the nail or remove early?
With ESIN/Métaizeau there is no agreement on retention time. Leaving the nail stabilises the epiphysis against secondary displacement, but adds a second anaesthetic for removal and a small risk of nail-end skin irritation. Practice ranges from a few weeks to several months.
Is reported PIN palsy iatrogenic?
Post-intervention nerve palsy rates (up to ~15% in operative series) blur injury-related and treatment-related causes. Whether percutaneous joystick or lateral elastic nailing genuinely raises iatrogenic PIN risk over the injury itself is unresolved, which is why baseline neurological documentation is mandatory.
Guidelines, Registries & Global Practice
The global consensus in one line
Across AAOS, BOA/BSCOS (UK), AO Foundation and EFORT/European paediatric practice, the philosophy is identical and evidence-consistent: accept and remodel modest angulation, reduce closed when over threshold, escalate to intramedullary (Métaizeau/ESIN) for severe displacement, and treat open reduction as a last resort. There is no formal single-society guideline document specific to this fracture, so practice rests on the technique and outcome literature rather than a named protocol.
Side-by-Side Practice Positions
| Body / region | Acceptable angulation | Preferred operative escalation | Emphasis |
|---|---|---|---|
| AAOS / North America | ~30° young, up to ~45° adolescent | Closed → percutaneous joystick → ESIN; open last | Remodelling potential, avoid arthrotomy stiffness |
| BOA / BSCOS (UK) | Conservative bias for moderate angulation | ESIN (Métaizeau) for severe displacement | Minimally invasive, day-case where possible |
| AO Foundation | Threshold ~30-45° by age | Intramedullary reduction/stabilisation favoured | Soft-tissue and vascular preservation |
| EFORT / European paediatric | Up to ~50° may remodel in young | Métaizeau ESIN as standard for displaced | Originator-driven technique adoption |
Global epidemiology
- Roughly 5-10% of paediatric elbow fractures and about 1% of all paediatric fractures
- Peak age 9-10 years; near-equal sex distribution
- Mechanism is consistent worldwide: fall on an outstretched hand with a valgus, axially loaded extended elbow
- Associated injuries in up to ~50% (elbow dislocation ~10%, olecranon, medial epicondyle, ulna)
Registries and data gaps
- No dedicated arthroplasty/implant registry captures this paediatric fracture (registries focus on adult joint replacement)
- Evidence base is retrospective series plus one systematic review/meta-analysis, not registry or trial data
- This evidence gap is itself an exam discussion point: management is consensus- and technique-driven
High-resource settings
- Image intensifier and elastic nails readily available, enabling closed Métaizeau/ESIN as the default for severe displacement
- Paediatric anaesthesia and day-surgery pathways support early closed intervention
- Ready access to nerve conduction studies for non-recovering PIN palsy
Limited-resource settings
- Without fluoroscopy or elastic nails, more reliance on closed manipulation and casting, with open reduction used earlier when closed fails
- Strong remodelling potential makes a conservative-first strategy both pragmatic and evidence-supported where implants are scarce
- Threshold for acceptance of residual angulation may be pushed higher when surgical capacity is limited
RADIAL NECK FRACTURES
Clinical summary
Angulation Thresholds
- •Less than 30° = non-operative (under 10 years)
- •Less than 45° = non-operative (over 10 years)
- •Greater than 30-45° = reduction indicated
- •Greater than 60° = percutaneous or ESIN/open
O'Brien Classification
- •Type I: less than 30° (non-operative)
- •Type II: 30-60° (closed reduction)
- •Type III: greater than 60° (perc/open)
- •Type IV: 90°/complete (usually open)
Reduction Escalation
- •Closed first (Patterson supination-valgus)
- •Then percutaneous K-wire joystick
- •Then Metaizeau ESIN
- •Open reduction LAST resort
Avoid Open Because
- •Stiffness up to 50%
- •AVN of radial head
- •Radioulnar synostosis
- •Higher overall complication rate
PIN Injury
- •5-10% incidence
- •Test finger/thumb extension
- •Usually neurapraxia
- •Recovery expected 3-6 months