Mason III/IV Fractures | Terrible Triad | PIN Protection | Sizing Critical
- 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
- “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
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.
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.
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.
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.
- Associated Injuries
- Isolated fracture
- Treatment
- RHA if greater than 3 fragments
- Key Consideration
- 80-85% good outcomes
- Associated Injuries
- Terrible triad
- Treatment
- RHA + coronoid fix + LCL repair
- Key Consideration
- All three components must be addressed
- Associated Injuries
- Essex-Lopresti
- Treatment
- RHA mandatory
- Key Consideration
- Never excise - causes migration
- Associated Injuries
- Stable elbow
- Treatment
- ORIF or conservative
- Key Consideration
- RHA not indicated
RCLTerrible Triad Components
Hook:RCL = Radial head, Coronoid, Ligament - all three must be addressed for terrible triad stability.
PRONATEPIN Protection
Hook:PRONATE protects PIN - full pronation is critical safety measure throughout procedure.
RADIALSizing Principles
Hook:RADIAL sizing prevents overlengthening - use radiocapitellar line on fluoro.
Overview and Epidemiology
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.
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.
- 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
- 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
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
- 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)
- 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
- 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
- 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)
- 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
- 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
- Swelling, ecchymosis
- Deformity (elbow, wrist)
- Carrying angle (cubitus valgus/varus)
- Lateral elbow tenderness (radial head)
- Wrist tenderness (DRUJ - Essex-Lopresti)
- Medial elbow tenderness (MCL injury)
- Flexion-extension: Normal 0-150°, functional arc 30-130°
- Pronation-supination: Normal 80° each direction
- Mechanical block: Test after aspiration and LA injection
- Valgus stress: MCL integrity (30° flexion)
- Varus stress: LCL integrity
- Posterolateral rotatory instability: Supination + valgus + axial load
- DRUJ instability: Piano key sign, ballottement
- Aspiration + LA injection: Differentiates true block from pain
- Biceps squeeze test: Assesses forearm stability
- DRUJ compression test: Essex-Lopresti
Investigations
- 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
- 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
- Ligament assessment: MCL, LCL integrity
- IOM evaluation: Essex-Lopresti (interosseous membrane tear)
- Cartilage assessment: Capitellar damage
- Intraoperative: Sizing verification, stability assessment
- Radiocapitellar line: Key landmark for proper height
Radiographic Examples
Differential Diagnosis and Controversies
Differential diagnosis - the painful, swollen lateral elbow after a fall:
- Key Clinical Clue
- Lateral tenderness, mechanical block, painful rotation
- Imaging Discriminator
- Comminution greater than 3 fragments on CT; positive fat-pad sign
- Management Pointer
- Replace if unreconstructable and/or unstable
- Key Clinical Clue
- Dislocation plus radial head plus coronoid injury
- Imaging Discriminator
- Coronoid fragment plus radial head fracture plus posterior dislocation
- Management Pointer
- Address all three components
- Key Clinical Clue
- Wrist/DRUJ pain accompanying radial head fracture
- Imaging Discriminator
- Proximal radius migration; DRUJ widening; IOM tear on MRI
- Management Pointer
- Replacement mandatory - never excise
- Key Clinical Clue
- Anterior pain, block to flexion
- Imaging Discriminator
- Lateral radiograph double-arc sign; CT confirms coronal shear
- Management Pointer
- ORIF of the capitellum, not radial head replacement
- Key Clinical Clue
- Apprehension, recurrent clicking, lateral pivot-shift
- Imaging Discriminator
- No fracture; stress views/MRI show LUCL disruption
- Management Pointer
- Ligament repair or reconstruction
- Key Clinical Clue
- Tenderness without block; full rotation after aspiration
- Imaging Discriminator
- Non-displaced or less than 2mm; effusion only
- Management Pointer
- 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.
Management Algorithm
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
- Mason classification
- Fragment number and size
- Reconstructability (less than 3 fragments = consider ORIF)
- Terrible triad components (coronoid, LCL)
- Essex-Lopresti (IOM, DRUJ)
- Capitellar damage
- MCL injury
- Measure radial head diameter on AP X-ray (typically 20-24mm)
- Measure height on lateral (typically 8-12mm)
- Compare with contralateral if available
- Modular vs monopolar
- Multiple sizes available
- Have backup sizes
- Kocher approach instruments
- Trial components
- Fluoroscopy
- Suture anchors (if ligament repair needed)
Proper planning ensures optimal sizing and addresses all injuries.
Complications
- Incidence
- 10-20%
- Risk Factors
- Inadequate sizing, poor fluoroscopic guidance
- Management
- Revision to shorter implant or radial head excision
- Incidence
- 30-50%
- Risk Factors
- HO, capsular adhesions, prolonged immobilization
- Management
- Manipulation under anesthesia (early) or arthroscopic arthrolysis (chronic)
- Incidence
- 20-50% without prophylaxis, 10-15% with indomethacin
- Risk Factors
- High-energy trauma, delay to surgery, head injury
- Management
- Indomethacin prophylaxis, excision if mature (12-18 months)
- Incidence
- 5-10%
- Risk Factors
- Inadequate LUCL repair, persistent LCL/coronoid insufficiency
- Management
- Revision ligament reconstruction
- Incidence
- 5-10% at 5-10 years
- Risk Factors
- High demand, overlengthening, malposition
- Management
- Revision or conversion to radial head excision
- Incidence
- 10-15%
- Risk Factors
- Overlengthening, malposition, excessive activity
- Management
- Implant removal ± interposition arthroplasty
- Incidence
- 0.5-2%
- Risk Factors
- Supination, distal dissection greater than 4-5cm, aggressive dissection
- Management
- Observation (most recover 3-6 months), exploration if no recovery
- Incidence
- 5-10% terrible triad
- Risk Factors
- Inadequate repair of LCL, coronoid, or MCL
- Management
- Revision ligament reconstruction or hinged external fixator
- Incidence
- 1-2%
- Risk Factors
- Open fractures, contamination
- Management
- Debridement, antibiotics, possible implant removal
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
- 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
- Progressive ROM exercises
- Begin gentle strengthening
- Return to light activities
- Full strengthening
- Return to activities 3-4 months
- Monitor for complications
Simple RHA rehabilitation is less restrictive than terrible triad.
Outcomes and Prognosis
- 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
- 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
- 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)
- Good: Proper sizing, stable fixation, early ROM, dedicated therapy
- Poor: Overlengthening, inadequate ligament repair, delayed surgery, non-compliance
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.
Detecting Overlengthening: the Ulnohumeral Congruity Sign
The topic makes overlengthening (over-stuffing) its dominant theme and teaches the radiocapitellar-line / lateral-coronoid-edge landmark for sizing - but it never notes that this landmark is unreliable for detecting a proud head, and that the ulnohumeral joint is the more sensitive indicator.
- Why the lateral landmark fails. A radial head only 2 mm proud is very hard to judge against the lateral coronoid edge or the radiocapitellar joint on fluoroscopy, which stay deceptively congruent; surgeons relying on the lateral view alone systematically over-lengthen.
- The more reliable sign: ulnohumeral incongruity. An overlengthened radial head props the lateral side of the elbow open, tilting the ulna into slight varus and WIDENING the MEDIAL ulnohumeral joint space (loss of the normal parallel, congruent ulnohumeral gap). So the best radiographic clue to over-stuffing is asymmetric widening or incongruity of the ulnohumeral joint (especially medially) on a true AP - not the radiocapitellar joint itself.
- Practical intra-operative rules.
- Compare directly with the excised native head - reassemble the removed fragments and match their combined height and diameter; this is the single most reliable reference.
- Restore, do not over-fill: when in doubt, choose the shorter or thinner trial - the failure modes of over-stuffing (capitellar erosion, stiffness, loosening) are far worse than a marginally short head.
- Check ulnohumeral congruity and full, smooth forearm rotation with the trial before committing to the definitive implant.
Q: Why is the radiocapitellar / lateral-coronoid landmark unreliable for detecting overlengthening, and what is better? A: A 2 mm-proud head keeps the radiocapitellar joint looking congruent, so surgeons relying on the lateral view systematically over-lengthen. An overstuffed head props the lateral elbow open and widens the MEDIAL ulnohumeral joint - so asymmetric ulnohumeral incongruity on a true AP is the more sensitive sign. Best of all: reassemble and measure the excised native head, and when in doubt pick the shorter trial, because over-stuffing (capitellar erosion, stiffness, loosening) is worse than a slightly short head.
Implant Design: Monopolar vs Bipolar and Stem Fixation
The Controversies section lists "monopolar vs bipolar" and "press-fit vs cemented vs loose spacer" stems, but the topic never explains these design choices - which are central to how radial head arthroplasty fails.
- Head coupling - monopolar vs bipolar.
- Monopolar (fixed head): the head is rigidly fixed to the stem. Simpler and provides more inherent stability, but the head cannot self-align, so malposition or over-stuffing concentrates edge-loading on the capitellum.
- Bipolar: the head articulates on a polyethylene bearing within the stem, allowing it to self-align to the capitellum through the arc of motion. This reduces edge-loading, and in the van Riet failure series no instability was seen with any bipolar implant - but it adds a polyethylene wear interface (potential osteolysis) and is felt by some to give less inherent stability in a grossly unstable elbow.
- Stem fixation - press-fit vs cemented vs loose "spacer".
- Press-fit (most common): relies on a tight metaphyseal fit, but painful loosening is the dominant failure mode (van Riet).
- Cemented: reserved for osteoporotic or over-reamed canals; more difficult to revise.
- Intentionally loose / smooth "spacer" stem: a deliberately polished, loose stem that pistons slightly and acts as a non-fixed spacer rather than a fixed implant - the rationale being that a stem designed to move avoids the painful loosening of a press-fit stem that was meant to be rigidly fixed.
- The unifying point. Because radial head implants are not captured by national arthroplasty registries, the monopolar-vs-bipolar and press-fit-vs-loose debates rest on institutional series and remain unresolved - itself an examinable point.
Q: What are the main radial head implant design choices and their trade-offs? A: Head coupling - monopolar (fixed) heads are simpler and more inherently stable but edge-load the capitellum if malpositioned; bipolar heads self-align on a polyethylene bearing (less edge-loading, no instability in the van Riet series) at the cost of a wear interface. Stem fixation - press-fit (commonest, but painful loosening dominates failures), cemented (osteoporotic/over-reamed canals), or an intentionally loose polished "spacer" stem designed to piston rather than fix. With no registry data, these debates are unresolved.
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.
- Position on Arthroplasty
- Replace unreconstructable comminuted heads (greater than 3 fragments) - prefer replacement over excision when the elbow or forearm is unstable
- Emphasis
- Restore the lateral column and forearm length; never excise in instability or Essex-Lopresti
- Position on Arthroplasty
- Arthroplasty for unreconstructable fractures, especially terrible triad and Essex-Lopresti; ORIF reserved for simple patterns
- Emphasis
- Modular metallic implants; avoid over-stuffing; early protected motion
- Position on Arthroplasty
- Replacement favoured for comminuted fractures with instability; isolated Mason III in low-demand stable elbows may be excised
- Emphasis
- Function-led rehabilitation; selective HO prophylaxis
- Position on Arthroplasty
- Replacement for comminution with associated instability; emphasises avoiding overlengthening and bipolar vs monopolar debate unresolved
- Emphasis
- Sizing discipline; registry-style 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.
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.
- 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
- 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.
MCQ Practice Points
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.
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.
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.
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.
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.
Exam Viva Scenarios
Practise clinical reasoning and management decisions out loud
“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.”
“How do you determine proper radial head prosthesis size, and what happens if you get it wrong?”
“A patient presents with radial head fracture and wrist pain. How do you assess for Essex-Lopresti injury, and why does it change management?”
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
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