Mason III/IV Fractures | Terrible Triad | PIN Protection | Sizing Critical
RHA INDICATIONS
Critical Must-Knows
- Mason III/IV fractures are primary indication - unreconstructable comminution
- Terrible triad requires addressing all three components (radial head, coronoid, LCL)
- PIN protection via full pronation moves nerve 4cm anterior to radial neck
- Sizing critical - radiocapitellar line on AP fluoro aligns with lateral coronoid edge
- Overlengthening is most common error (10-20%) causing capitellar erosion and stiffness
Clinical Pearls
- "Kocher approach: internervous plane between anconeus (radial nerve) and ECU (PIN)
- "Full pronation protects PIN - moves from 1.5cm (supination) to 4cm (pronation) from neck
- "Radiocapitellar line: radial head should align with lateral edge of coronoid on AP fluoro
- "Terrible triad: all three components must be addressed for stability
Clinical Imaging
Imaging Gallery



Critical Radial Head Arthroplasty Exam Points
Terrible Triad Management
All three components must be addressed: radial head replacement, coronoid fixation if greater than 50% height, and LUCL repair. Failure to address any component leads to persistent instability and poor outcome. This is a pattern of instability, not just a radial head fracture.
PIN Protection Critical
Full pronation moves PIN from 1.5cm (supination) to 4cm (pronation) anterior to radial neck. This is the most important safety measure. PIN injury occurs in 0.5-2% and causes motor weakness (wrist/finger extension). Most recover but some permanent.
Sizing is Everything
Radiocapitellar line on AP fluoroscopy: radial head should align with lateral edge of coronoid. Overlengthening (most common error, 10-20%) causes capitellar erosion, pain, stiffness. Underlengthening causes instability. Use trial components and fluoro confirmation.
Essex-Lopresti Recognition
Radial head + IOM + DRUJ disruption. Radial head replacement is MANDATORY - never excise as this causes proximal radius migration and DRUJ destruction. Always check wrist for tenderness and DRUJ instability with radial head fractures.
Quick Decision Guide - Radial Head Arthroplasty
| Fracture Pattern | Associated Injuries | Treatment | Key Consideration |
|---|---|---|---|
| Mason III comminuted | Isolated fracture | RHA if greater than 3 fragments | 80-85% good outcomes |
| Mason IV with dislocation | Terrible triad | RHA + coronoid fix + LCL repair | All three components must be addressed |
| Mason III/IV | Essex-Lopresti | RHA mandatory | Never excise - causes migration |
| Mason I/II | Stable elbow | ORIF or conservative | RHA not indicated |
RCLTerrible Triad Components
| R | Radial head fracture Usually Mason III/IV, comminuted |
| C | Coronoid fracture Anterior buttress, fix if greater than 50% height |
| L | LCL/LUCL injury Primary lateral stabilizer, must repair |
| R | Radial head fracture Usually Mason III/IV, comminuted |
| C | Coronoid fracture Anterior buttress, fix if greater than 50% height |
| L | LCL/LUCL injury Primary lateral stabilizer, must repair |
Hook:RCL = Radial head, Coronoid, Ligament - all three must be addressed for terrible triad stability.
PRONATEPIN Protection
| P | Pronate forearm Full pronation moves PIN anteriorly |
| R | Radial nerve branch PIN is terminal motor branch |
| O | Only 4cm safe Pronation moves PIN 4cm from neck |
| N | Never supinate Supination brings PIN to 1.5cm - dangerous |
| A | Avoid distal dissection Stay less than 4-5cm from epicondyle |
| T | Test after surgery Check wrist/finger extension |
| E | Early recognition Most PIN injuries recover 3-6 months |
| P | Pronate forearm Full pronation moves PIN anteriorly | N | Never supinate Supination brings PIN to 1.5cm - dangerous | E | Early recognition Most PIN injuries recover 3-6 months |
| R | Radial nerve branch PIN is terminal motor branch | A | Avoid distal dissection Stay less than 4-5cm from epicondyle | ||
| O | Only 4cm safe Pronation moves PIN 4cm from neck | T | Test after surgery Check wrist/finger extension |
Hook:PRONATE protects PIN - full pronation is critical safety measure throughout procedure.
RADIALSizing Principles
| R | Radiocapitellar line AP fluoro - head aligns with lateral coronoid edge |
| A | Avoid overlengthening Most common error (10-20%), causes capitellar erosion |
| D | Diameter match native Typically 20-24mm, range 18-26mm |
| I | Intraoperative sizing Use trial components and fluoro |
| A | Assess through ROM Check stability and impingement |
| L | Lateral coronoid edge Key fluoroscopic landmark for height |
| R | Radiocapitellar line AP fluoro - head aligns with lateral coronoid edge | D | Diameter match native Typically 20-24mm, range 18-26mm | A | Assess through ROM Check stability and impingement |
| A | Avoid overlengthening Most common error (10-20%), causes capitellar erosion | I | Intraoperative sizing Use trial components and fluoro | L | Lateral coronoid edge Key fluoroscopic landmark for height |
Hook:RADIAL sizing prevents overlengthening - use radiocapitellar line on fluoro.
Overview and Epidemiology
Definition: Radial head arthroplasty (RHA) is replacement of the comminuted radial head with a metallic prosthesis to restore lateral elbow stability, radiocapitellar articulation, and forearm load transmission. It is indicated for unreconstructable radial head fractures, particularly in the setting of elbow instability.
Historical Context: Radial head arthroplasty has evolved from simple excision (historically common but causes problems) to modern modular prostheses allowing precise restoration of anatomy. Recognition that radial head is a critical stabilizer (especially in MCL-deficient elbows) has made replacement the standard over excision in most cases.
Current Indications:
- Mason III fractures: Comminuted greater than 3 fragments not amenable to stable ORIF
- Mason IV fractures: With elbow dislocation (terrible triad variant)
- Terrible triad: Radial head + coronoid + LCL injury requiring all three components addressed
- Essex-Lopresti: Radial head + IOM + DRUJ disruption (replacement mandatory)
- Failed ORIF: Symptomatic malunion or nonunion
Epidemiology:
- Frequency: Common procedure in trauma centers (1-2 per month)
- Age: Peak 30-50 years (trauma), older for isolated fractures
- Gender: Equal distribution (trauma-related)
- Trend: Increasing use of modular systems for better sizing
Why Radial Head Matters
The radial head is a secondary valgus stabilizer (critical if MCL torn), provides lateral buttress preventing posterolateral instability, maintains radiocapitellar load transmission, and prevents proximal radius migration in Essex-Lopresti. Excision causes predictable problems in unstable elbows - replacement is mandatory in these settings.
Anatomy and Biomechanics
Radial Head Anatomy:
Osseous Structure:
- Articular surface: Concave, articulates with capitellum (radiocapitellar joint)
- Radial notch: Articulates with ulna (proximal radioulnar joint)
- Diameter: 18-26mm (typically 20-24mm)
- Height: 8-12mm from neck to articular surface
- Safe zone: 90-110° arc that does not articulate with PRUJ (for hardware placement)
Ligamentous Anatomy:
Lateral Collateral Ligament Complex:
- LUCL (lateral ulnar collateral ligament): Primary restraint to posterolateral rotatory instability
- Origin: Lateral epicondyle
- Insertion: Crista supinatoris of ulna
- Function: Prevents radial head subluxation posteriorly
- Annular ligament: Encircles radial head, maintains PRUJ
- Radial collateral ligament: Secondary varus stabilizer
Nerve Anatomy (CRITICAL):
Posterior Interosseous Nerve (PIN):
- Course: Terminal motor branch of radial nerve
- Location: Passes through supinator muscle 4-5cm distal to lateral epicondyle
- Function: Innervates wrist and finger extensors
- Risk: Injury causes motor weakness (wrist/finger extension)
- Protection: Full pronation moves PIN from 1.5cm (supination) to 4cm (pronation) anterior to radial neck
Biomechanics:
Radial Head Functions:
- Secondary valgus stabilizer: Critical if MCL torn
- Lateral buttress: Prevents posterolateral instability
- Load transmission: 60% of axial load through radiocapitellar joint
- Forearm stability: Prevents proximal radius migration (Essex-Lopresti)
After Arthroplasty:
- Restores lateral stability
- Maintains radiocapitellar articulation
- Prevents proximal migration
- Allows early motion
Classification Systems
Mason Classification of Radial Head Fractures
Type I: Non-displaced
- Less than 2mm displacement
- No mechanical block
- Treatment: Conservative (sling, early ROM)
- Outcome: Excellent (90-95%)
Type II: Displaced Partial Head
- Greater than 2mm displacement
- May have mechanical block
- Treatment: ORIF if block, otherwise conservative
- Outcome: Good (80-85%)
Type III: Comminuted Entire Head
- Greater than 3 fragments
- Unreconstructable
- Treatment: Replacement or excision (if stable, low demand)
- Outcome: Variable (70-85% with replacement)
Type IV: With Elbow Dislocation
- Radial head fracture + dislocation
- Often terrible triad
- Treatment: Replacement + address instability
- Outcome: Worse (60-75% with proper management)
Mason classification guides treatment decisions and predicts outcomes.
Clinical Assessment
History:
- Mechanism of injury (FOOSH, direct trauma)
- Pain location (lateral elbow, wrist)
- Mechanical block to motion
- Instability symptoms (giving way, apprehension)
- Wrist symptoms (Essex-Lopresti)
Physical Examination:
Inspection:
- Swelling, ecchymosis
- Deformity (elbow, wrist)
- Carrying angle (cubitus valgus/varus)
Palpation:
- Lateral elbow tenderness (radial head)
- Wrist tenderness (DRUJ - Essex-Lopresti)
- Medial elbow tenderness (MCL injury)
Range of Motion:
- Flexion-extension: Normal 0-150°, functional arc 30-130°
- Pronation-supination: Normal 80° each direction
- Mechanical block: Test after aspiration and LA injection
Stability Testing:
- Valgus stress: MCL integrity (30° flexion)
- Varus stress: LCL integrity
- Posterolateral rotatory instability: Supination + valgus + axial load
- DRUJ instability: Piano key sign, ballottement
Special Tests:
- Aspiration + LA injection: Differentiates true block from pain
- Biceps squeeze test: Assesses forearm stability
- DRUJ compression test: Essex-Lopresti
Investigations
Plain Radiographs:
- AP and lateral elbow: Fracture pattern, displacement, dislocation
- Radiocapitellar oblique: Better visualization of radial head
- Wrist X-rays: DRUJ assessment (Essex-Lopresti)
- Contralateral elbow: Templating for sizing
CT Scan:
- 3D reconstruction: Essential for complex fractures
- Fragment assessment: Number, size, reconstructability
- Coronoid evaluation: Percentage of height, fragment type
- Associated injuries: Capitellum, medial epicondyle
- Loose bodies: Detection
MRI:
- Ligament assessment: MCL, LCL integrity
- IOM evaluation: Essex-Lopresti (interosseous membrane tear)
- Cartilage assessment: Capitellar damage
Fluoroscopy:
- Intraoperative: Sizing verification, stability assessment
- Radiocapitellar line: Key landmark for proper height
Radiographic Examples



Management Algorithm

Decision Framework
The key decision is ORIF vs replacement vs excision. ORIF for reconstructable fractures (less than 3 fragments). Replacement for unreconstructable fractures, especially with instability. Excision only for isolated fractures in low-demand elderly with stable elbows.
Decision Tree
Step 1: Assess Fracture Pattern
- Mason I: Conservative
- Mason II: ORIF if mechanical block, otherwise conservative
- Mason III: Replacement if greater than 3 fragments
- Mason IV: Replacement + address instability
Step 2: Assess Associated Injuries
- Terrible triad? → Address all three components
- Essex-Lopresti? → Replacement mandatory (never excise)
- Isolated fracture? → Replacement or excision (if stable, low demand)
Step 3: Assess Stability
- Stable elbow? → Replacement or excision (if low demand)
- Unstable elbow? → Replacement mandatory (never excise)
Step 4: Patient Factors
- Age, demand, compliance
- Bone quality
- Functional requirements
The goal is stable elbow with functional ROM and prevention of long-term complications.
Surgical Technique
Pre-operative Planning Steps
1. Fracture Assessment:
- Mason classification
- Fragment number and size
- Reconstructability (less than 3 fragments = consider ORIF)
2. Associated Injuries:
- Terrible triad components (coronoid, LCL)
- Essex-Lopresti (IOM, DRUJ)
- Capitellar damage
- MCL injury
3. Templating:
- Measure radial head diameter on AP X-ray (typically 20-24mm)
- Measure height on lateral (typically 8-12mm)
- Compare with contralateral if available
4. Implant Selection:
- Modular vs monopolar
- Multiple sizes available
- Have backup sizes
5. Equipment:
- Kocher approach instruments
- Trial components
- Fluoroscopy
- Suture anchors (if ligament repair needed)
Proper planning ensures optimal sizing and addresses all injuries.
Complications
| Complication | Incidence | Risk Factors | Management |
|---|---|---|---|
| Overlengthening | 10-20% | Inadequate sizing, poor fluoroscopic guidance | Revision to shorter implant or radial head excision |
| Stiffness | 30-50% | HO, capsular adhesions, prolonged immobilization | Manipulation under anesthesia (early) or arthroscopic arthrolysis (chronic) |
| Heterotopic ossification | 20-50% without prophylaxis, 10-15% with indomethacin | High-energy trauma, delay to surgery, head injury | Indomethacin prophylaxis, excision if mature (12-18 months) |
| Posterolateral rotatory instability | 5-10% | Inadequate LUCL repair, persistent LCL/coronoid insufficiency | Revision ligament reconstruction |
| Implant loosening | 5-10% at 5-10 years | High demand, overlengthening, malposition | Revision or conversion to radial head excision |
| Capitellar erosion | 10-15% | Overlengthening, malposition, excessive activity | Implant removal ± interposition arthroplasty |
| PIN palsy | 0.5-2% | Supination, distal dissection greater than 4-5cm, aggressive dissection | Observation (most recover 3-6 months), exploration if no recovery |
| Instability/recurrent dislocation | 5-10% terrible triad | Inadequate repair of LCL, coronoid, or MCL | Revision ligament reconstruction or hinged external fixator |
| Infection | 1-2% | Open fractures, contamination | Debridement, antibiotics, possible implant removal |
Most Common Complication: Overlengthening
Overlengthening is the most common technical error (10-20% incidence). It causes increased radiocapitellar contact pressure leading to capitellar cartilage erosion, pain, stiffness, accelerated arthritis, and early failure. Prevention requires meticulous sizing using radiocapitellar line on AP fluoroscopy (radial head aligns with lateral edge of coronoid). Treatment requires revision to shorter implant or radial head excision.
Postoperative Care and Rehabilitation
Isolated Radial Head Arthroplasty
Early (0-2 weeks):
- Splint 5-7 days for comfort
- Remove sutures 10-14 days
- Begin active-assisted ROM immediately after splint removal
- Full active ROM by 2-3 weeks
Intermediate (2-6 weeks):
- Progressive ROM exercises
- Begin gentle strengthening
- Return to light activities
Late (6-12 weeks):
- Full strengthening
- Return to activities 3-4 months
- Monitor for complications
Simple RHA rehabilitation is less restrictive than terrible triad.
Outcomes and Prognosis
Isolated Radial Head Arthroplasty:
- Good to excellent outcomes: 80-85%
- Functional ROM: 30-130° flexion, full rotation in 80-85%
- Pain relief: 85-90% achieve good to excellent pain control
- Return to activities: 3-4 months for light activities, 6 months for sports
Terrible Triad with RHA:
- Satisfactory outcomes: 70-75% (worse due to complexity)
- Functional ROM: 60-70% achieve 100° arc
- Stability: 80-90% have stable elbow after surgery
- Complications: 30-40% develop stiffness, 10-15% HO, 5-10% PLRI
Long-term Considerations:
- Implant survival: 90-95% at 5 years, 85-90% at 10 years
- Revision rate: 5-10% at 5-10 years (mostly loosening or overlengthening)
- Capitellar erosion: 10-15% develop progressive capitellar wear
- Adjacent joint problems: Rare (unlike radial head excision)
Predictors of Success:
- Good: Proper sizing, stable fixation, early ROM, dedicated therapy
- Poor: Overlengthening, inadequate ligament repair, delayed surgery, non-compliance
Outcome Expectations
Isolated radial head arthroplasty has excellent outcomes (80-85% good/excellent). Terrible triad outcomes are worse (70-75% satisfactory) due to complexity, stiffness, and instability issues. Most important predictor of outcome is achieving functional ROM - stiffness is the enemy. Dedicated hand therapy is critical for good outcomes.
Evidence Base and Key Trials
Standard Protocol for Terrible Triad (Landmark)
- 36 consecutive elbow dislocations with radial head and coronoid fractures treated by a standard protocol
- Protocol: radial head fixation or replacement, coronoid fixation when possible, lateral ligament repair, selective MCL repair and hinged external fixation
- Mean Mayo Elbow Performance Score 88 (15 excellent, 13 good, 7 fair, 1 poor); concentric stability restored in 34 of 36 elbows
- Stable construct allowed motion at 7-10 days; 8 patients needed reoperation (synostosis, instability, hardware removal/release, infection)
Radial Head Replacement vs Repair in Terrible Triad (Meta-analysis)
- Systematic review and meta-analysis of 4 studies, 115 patients (51 repair, 64 replacement)
- Replacement associated with significantly better flexion, extension and pronation ROM than repair
- Replacement group showed better DASH and MEPS scores and fewer post-surgical complications
- Most fractures were Mason type II or III
Replacement vs ORIF for Mason III Fractures (Meta-analysis)
- Pooled one RCT and one comparative study, 67 patients with Mason type III fractures
- Complication rate 13.9% with replacement vs 58.1% with ORIF
- Satisfactory outcome 91.7% with replacement vs 51.6% with ORIF
- Replacement favoured at follow-up of 5 years or less
Differential Diagnosis and Controversies
Differential diagnosis - the painful, swollen lateral elbow after a fall:
Differentiating Causes of Acute Lateral Elbow Pain (FOOSH)
| Condition | Key Clinical Clue | Imaging Discriminator | Management Pointer |
|---|---|---|---|
| Radial head fracture (Mason III/IV) | Lateral tenderness, mechanical block, painful rotation | Comminution greater than 3 fragments on CT; positive fat-pad sign | Replace if unreconstructable and/or unstable |
| Terrible triad | Dislocation plus radial head plus coronoid injury | Coronoid fragment plus radial head fracture plus posterior dislocation | Address all three components |
| Essex-Lopresti injury | Wrist/DRUJ pain accompanying radial head fracture | Proximal radius migration; DRUJ widening; IOM tear on MRI | Replacement mandatory - never excise |
| Capitellar (Hahn-Steinthal) fracture | Anterior pain, block to flexion | Lateral radiograph double-arc sign; CT confirms coronal shear | ORIF of the capitellum, not radial head replacement |
| Isolated LCL injury / PLRI | Apprehension, recurrent clicking, lateral pivot-shift | No fracture; stress views/MRI show LUCL disruption | Ligament repair or reconstruction |
| Radial head/neck contusion or Mason I | Tenderness without block; full rotation after aspiration | Non-displaced or less than 2mm; effusion only | Non-operative, early motion |
Areas of genuine uncertainty (exam-relevant controversies):
- Replace vs reconstruct the borderline 3-fragment head: meta-analytic data favour replacement over ORIF for true comminution (Li 2013; Chen 2019), but a stable, anatomically reducible head in a young patient may still justify fixation to preserve native bone.
- Monopolar vs bipolar implants: bipolar designs may reduce edge-loading and were not associated with instability in the van Riet failure series, but they introduce a polyethylene-bearing wear interface; no registry-level comparison exists.
- Press-fit vs cemented vs loose ("spacer") stems: loosening is the dominant failure mode; some advocate an intentionally loose smooth stem to act as a spacer, others press-fit for stability - the evidence is institutional, not randomised.
- Excision in the modern era: still defensible for an isolated comminuted head in a low-demand, demonstrably stable elbow, but contraindicated with any instability or Essex-Lopresti.
- Routine HO prophylaxis: indomethacin/radiotherapy are reasonable in high-risk injuries but lack strong evidence for routine isolated arthroplasty; early motion is the most reproducible measure.
- Implant longevity data gap: absence of national-registry capture means true long-term survival of radial head implants remains poorly defined.
Exam Viva Scenarios
Use these scenarios to practise clinical reasoning and management decisions
Scenario 1: Terrible Triad Management (~3-4 min)
"A 45-year-old patient presents with terrible triad injury. Walk me through your management, including surgical approach, addressing all components, and key technical points."
Scenario 2: Sizing and Overlengthening (~2-3 min)
"How do you determine proper radial head prosthesis size, and what happens if you get it wrong?"
Scenario 3: Essex-Lopresti Recognition (~2-3 min)
"A patient presents with radial head fracture and wrist pain. How do you assess for Essex-Lopresti injury, and why does it change management?"
MCQ Practice Points
Indications Question
Q: What is the primary indication for radial head arthroplasty? A: Mason III/IV comminuted radial head fractures that are unreconstructable (greater than 3 fragments). Also indicated in terrible triad and Essex-Lopresti injuries where radial head replacement is mandatory for stability.
Surgical Technique Question
Q: How do you protect the posterior interosseous nerve during Kocher approach? A: Full pronation of the forearm moves PIN from 1.5cm (supination) to 4cm (pronation) anterior to radial neck. This is the most important safety measure. Also limit distal dissection to less than 4-5cm from lateral epicondyle.
Sizing Question
Q: How do you determine proper radial head prosthesis height? A: Radiocapitellar line on AP fluoroscopy: radial head should align with lateral edge of coronoid process. Overlengthening (most common error, 10-20%) causes capitellar erosion, pain, and stiffness. Use trial components and fluoro confirmation before final implant.
Terrible Triad Question
Q: What are the three components of terrible triad and how are they managed? A: Radial head fracture (replacement), coronoid fracture (fix if greater than 50% height), and LCL injury (repair). All three must be addressed for stability. Failure to address any component leads to persistent instability and poor outcome.
Complications Question
Q: What is the most common technical error in radial head arthroplasty? A: Overlengthening occurs in 10-20% of cases. It causes increased radiocapitellar contact pressure leading to capitellar cartilage erosion, pain, stiffness, and early failure. Prevention requires meticulous sizing using radiocapitellar line on AP fluoroscopy.
Guidelines, Registries & Global Practice
Global epidemiology:
- Radial head fractures account for roughly one-third of all elbow fractures and around 1.5-4% of all adult fractures; peak incidence is in the third to sixth decades with a slight female predominance in older cohorts (low-energy falls) and a male predominance in younger high-energy trauma.
- Around 20-30% of radial head fractures are associated with another osseous or ligamentous injury (terrible triad, coronoid, capitellum, MCL, Essex-Lopresti) - this association, not the fracture in isolation, drives the decision to replace.
- Mason III/IV patterns make up a minority of all radial head fractures but represent the majority of arthroplasty indications.
Side-by-side Society Positions on Radial Head Management
| Body / Region | Position on Arthroplasty | Emphasis |
|---|---|---|
| AO Foundation (global) | Replace unreconstructable comminuted heads (greater than 3 fragments) - prefer replacement over excision when the elbow or forearm is unstable | Restore the lateral column and forearm length; never excise in instability or Essex-Lopresti |
| AAOS / ASSH (US) | Arthroplasty for unreconstructable fractures, especially terrible triad and Essex-Lopresti; ORIF reserved for simple patterns | Modular metallic implants; avoid over-stuffing; early protected motion |
| BOA / BSSH (UK) | Replacement favoured for comminuted fractures with instability; isolated Mason III in low-demand stable elbows may be excised | Function-led rehabilitation; selective HO prophylaxis |
| EFORT / European consensus | Replacement for comminution with associated instability; emphasises avoiding overlengthening and bipolar vs monopolar debate unresolved | Sizing discipline; registry-style implant surveillance |
Registry & Implant Surveillance
Unlike hip and knee arthroplasty, radial head implants are not comprehensively captured by the large national joint registries (NJR-UK, AJRR-US, AOANJRR-Australia, SHAR-Sweden). Evidence on implant survival therefore comes from institutional series and systematic reviews rather than registry data - explaining the persisting uncertainty over bipolar vs monopolar and press-fit vs cemented designs.
High- vs Limited-Resource Practice
Well-resourced centres use modular metallic systems with intra-operative fluoroscopy and a full range of trial heads/necks. Where modular implants, fluoroscopy or hand-therapy are limited, radial head excision (in a demonstrably stable elbow) or ORIF remains a legitimate fallback - but excision is contraindicated whenever instability or Essex-Lopresti is present, regardless of resource setting.
Documentation and Quality Points (Globally Applicable)
Key operative-record points:
- Pre-operative assessment of associated injuries (terrible triad, coronoid, Essex-Lopresti/wrist)
- PIN protection strategy (forearm pronation, dissection limited near the neck)
- Sizing technique (radiocapitellar line on AP fluoroscopy; avoid overlengthening/over-stuffing)
- Confirmation that all destabilising components were addressed
- HO-prophylaxis decision and rationale in high-risk injuries
Recurring sources of poor outcome:
- PIN injury where protective measures were not applied
- Overlengthening causing capitellar erosion and stiffness
- Missed terrible triad components leading to recurrent instability
- Excising the radial head in an unstable elbow or Essex-Lopresti injury
A systematic, well-documented approach minimises avoidable complications worldwide.
Radial Head Arthroplasty
Clinical summary
Key Indications
- •Mason III/IV comminuted fractures (greater than 3 fragments)
- •Terrible triad: radial head + coronoid + LCL (all three must be addressed)
- •Essex-Lopresti: radial head + IOM + DRUJ (replacement mandatory)
- •Failed ORIF with symptomatic malunion/nonunion
Surgical Technique
- •Kocher approach: internervous plane (anconeus-ECU)
- •PIN protection: FULL PRONATION moves nerve 4cm anterior to neck
- •Sizing: radiocapitellar line on AP fluoro - head aligns with lateral coronoid edge
- •LUCL repair: suture anchors in lateral epicondyle if torn
- •Coronoid fixation: suture lasso or anchors if greater than 50% height
Complications
- •Overlengthening: 10-20% (most common error) - causes capitellar erosion
- •Stiffness: 30-50% - managed with aggressive therapy
- •HO: 10-15% with indomethacin prophylaxis
- •PIN palsy: 0.5-2% - most recover 3-6 months
- •PLRI: 5-10% if inadequate LUCL repair
Outcomes
- •Isolated RHA: 80-85% good to excellent outcomes
- •Terrible triad: 70-75% satisfactory outcomes
- •Functional ROM: 30-130° flexion, full rotation in 80-85%
- •Return to activities: 3-4 months light, 6 months sports