Tillaux (SH-III) | Triplane (SH-IV) | Adolescent Ankle | CT Essential
- Occur during physeal closure - Central, Medial, then Lateral (CML)
- Tillaux = SH-III - anterolateral epiphysis only
- Triplane = SH-IV - epiphysis + metaphysis (2 or 3 part)
- CT is essential to determine fracture configuration and step-off
- Greater than 2mm articular step-off requires ORIF
- “Tillaux and Triplane are NOT adult ankle fractures
- “CT defines 2-part vs 3-part triplane pattern
- “Anterolateral fragment in Tillaux is attached to AITFL
- “Near skeletal maturity means low growth arrest risk
X-rays underestimate displacement. CT scan is essential to determine 2-part vs 3-part triplane, measure articular step-off, and plan surgical approach.
The distal tibial physis closes Central, Medial, Lateral (CML) over 18 months. Transitional fractures occur when lateral physis is still open.
Greater than 2mm articular step-off is the threshold for operative treatment. Measure on CT axial and sagittal reformats.
These occur near skeletal maturity, so growth arrest is rarely clinically significant. Focus on articular reduction.
| Scenario | Fracture Type | Treatment | Key Pearl |
|---|---|---|---|
| Less than 2mm step on CT | Tillaux or Triplane | Long leg cast 4-6 weeks | Weekly X-rays to check displacement |
| Greater than 2mm step on CT | Tillaux | ORIF via anterolateral approach | Single epiphyseal screw |
| Greater than 2mm step on CT | 2-Part Triplane | ORIF - one approach may suffice | Lateral approach, epiphyseal + metaphyseal screws |
| Greater than 2mm step on CT | 3-Part Triplane | ORIF - may need medial approach | Fix medial epiphyseal fragment separately |
CMLPhyseal Closure Pattern
Hook:CML - Closes in the Middle, then Later Lateral leaves the anterolateral fragment vulnerable!
TILTTillaux Key Features
Hook:The Tillaux TILTs when AITFL pulls the anterolateral fragment!
STEPTriplane Decision Making
Hook:STEP through the CT to plan your surgery - don't skip the scan!
Overview/Epidemiology
Transitional fractures are unique pediatric ankle injuries occurring during the 18-month period of asymmetric distal tibial physeal closure.
Mechanism:
- External rotation of the foot on a fixed leg (similar to adult ankle fracture mechanism).
- The anterolateral fragment is avulsed via the anterior inferior tibiofibular ligament (AITFL).
- The pattern depends on which portions of the physis remain open.
Clinical Significance:
- These are intra-articular injuries requiring anatomic reduction.
- Growth arrest is rarely clinically significant due to near-skeletal maturity.
- Focus is on articular congruity, not physeal preservation.
Anatomy and Pathomechanics

Physeal Closure Pattern (CML):
- The distal tibial physis closes asymmetrically over approximately 18 months.
- Central portion closes first (age 12-13).
- Medial portion closes next (age 14-15).
- Lateral (anterolateral) portion closes last (age 15-16).
When the medial physis has fused but the lateral remains open, external rotation forces cause the AITFL to avulse the anterolateral epiphyseal fragment - creating a Tillaux fracture. If the force propagates into the metaphysis, a Triplane results.
Key Anatomy:
- AITFL (Anterior Inferior Tibiofibular Ligament): Attaches to the anterolateral tibia (Tillaux fragment).
- Lateral malleolus: Usually intact (not fractured in pure transitional fractures).
- Fibular physis: Closes earlier than tibial physis.
Fracture Planes in Triplane:
- Sagittal through the epiphysis (separating anterior from posterior).
- Transverse/Axial through the physis.
- Coronal through the metaphysis.
Hence the name "triplane" - three planes of fracture.
Classification Systems
Tillaux Fracture (Juvenile Tillaux)
Salter-Harris Type III
- Involves physis and epiphysis only.
- Anterolateral epiphyseal fragment.
- Occurs when only the lateral physis remains open.
| Feature | Tillaux | Adult Chaput Tubercle |
|---|---|---|
| Age | 12-15 years | Adult |
| Physis | Partially open | Closed |
| Metaphysis | Intact | May be involved |
Treatment: ORIF if more than 2mm articular step-off.
This represents the final stage of the transitional fracture spectrum.
Differential Diagnosis
The anterolateral painful adolescent ankle after a twisting injury has a tight differential. The pivotal discriminator is patient age and physeal status - the same external-rotation force produces a ligament sprain in an adult but a physeal fracture in an adolescent because the open physis is weaker than the AITFL.
| Diagnosis | Typical Age | Salter-Harris / Pattern | Key Discriminator | Imaging Clue |
|---|---|---|---|---|
| Juvenile Tillaux | 12-15 (lateral physis open) | SH-III | Isolated anterolateral epiphyseal fragment, metaphysis intact | Mortise view + axial CT: single epiphyseal fragment |
| Triplane fracture | 10-14 (more physis open than Tillaux) | SH-IV (multiplanar) | Epiphyseal + metaphyseal involvement, 2 or 3 fragments | Lateral X-ray looks SH-II, AP looks SH-III; CT resolves |
| Adult Tillaux-Chaput avulsion | Skeletally mature | Intra-articular avulsion | Physis closed, often with syndesmotic injury | No physeal lucency; assess syndesmosis |
| Weber B/C ankle fracture | Adult | Fibular fracture +/- medial | Fibula fractured; physes closed | Talar shift, fibular fracture line |
| Distal tibial SH-I/II (younger child) | Under 12 (whole physis open) | SH-I / SH-II | Whole physis open, metaphyseal Thurston-Holland fragment | No isolated anterolateral fragment |
| Lateral ankle ligament sprain | Any (but rare to be pure in adolescent) | Soft-tissue | No bony tenderness over physis, normal films | Normal radiographs; MRI shows ligament only |
A 13-year-old who has "just sprained an ankle" with point tenderness over the anterolateral distal tibia has a Tillaux fracture until proven otherwise. In the adolescent the physis fails before the ligament, so dedicated radiographs (and CT if a fragment is seen) are mandatory before labelling it a sprain.
Clinical Assessment
- Mechanism: Rotational injury (external rotation of foot).
- Age: 12-15 years (crucial - physis must be closing).
- Pain location: Anterolateral ankle.
- Weight-bearing: Usually unable.
- Inspection: Swelling, ecchymosis anterolaterally.
- Palpation: Point tenderness over anterolateral physis.
- Movement: Painful ROM, especially external rotation.
- Neurovascular: Document (usually intact).
Differentiation from Adult Ankle Fractures:
- Age is the key factor.
- In adolescents, the physis is weaker than the ligaments.
- Similar mechanisms cause physeal fractures, not ligament sprains.
Investigations
Imaging Protocol
AP, Lateral, Mortise views. Look for physeal widening laterally, epiphyseal fragment on mortise view. X-rays often underestimate displacement.
Mandatory for all transitional fractures. Determines 2-part vs 3-part pattern, measures articular step-off accurately, and guides surgical approach.
Rarely needed. May help if diagnosis unclear or to assess soft tissue/ligament injury.
Plain radiographs consistently underestimate displacement. A fracture that appears 1-2mm on X-ray may be more than 2mm on CT. Always get a CT before deciding on non-operative treatment.
Management Algorithm
Non-Displaced or Minimally Displaced (Less than 2mm on CT)
Indications:
- Articular step-off less than 2mm on CT.
- Acceptable alignment on X-ray.
Treatment Protocol:
- Long leg cast or CAM boot for 4-6 weeks.
- Non-weight bearing initially, then progressive WB.
- Weekly X-rays for 2-3 weeks to ensure no displacement.
Early displacement is possible. If step-off increases beyond 2mm on follow-up X-ray, convert to operative treatment.
Surgical Techniques
Patient Positioning
Position: Supine on radiolucent table. Padding: Bump under ipsilateral hip (slight internal rotation of leg). Draping: Free drape the lower extremity for manipulation. C-arm: From contralateral side for AP, mortise, and lateral views.
A small bump under the hip internally rotates the leg, making the anterolateral approach more accessible.
Intraoperative Tips:
- Use fluoroscopy liberally to confirm reduction.
- The articular surface should be anatomic (less than 1-2mm step).
- Avoid screw penetration into the joint.
Complications
| Complication | Incidence | Risk Factors | Management |
|---|---|---|---|
| Malunion/Step-off | Variable | Non-anatomic reduction | Accept less than 2mm, revise if more |
| Arthritis | Rare short-term | Articular incongruity | Anatomic reduction prevents |
| Growth Arrest | Rare clinically | Near maturity | Usually not significant |
| Stiffness | Uncommon | Prolonged immobilization | Early mobilization |
| Superficial Peroneal Nerve | Rare | Lateral approach | Careful dissection |
Unlike more proximal physeal injuries, growth arrest in transitional fractures is rarely clinically significant because these patients are near skeletal maturity. Focus on articular reduction rather than physeal preservation.
Postoperative Care
Rehabilitation Protocol
Backslab initially, convert to short leg cast. Non-weight bearing. Elevation, ice.
Short leg cast or CAM boot. Non-weight bearing continues. Check X-rays at 2-4 weeks.
If healing confirmed, transition to weight-bearing as tolerated in boot. Begin gentle ankle ROM.
Wean from boot. Physiotherapy for ROM and strength. Return to sport at 3 months if healed and strong.
Hardware:
- Screws are usually left in situ unless symptomatic.
- No routine removal needed.
Outcomes/Prognosis
Prognostic Factors:
- Articular reduction quality is the main determinant of outcome.
- Greater than 2mm step is associated with increased arthritis risk.
- Growth arrest, if it occurs, is usually not clinically significant.
Return to Activity:
- Most return to full sport by 3-4 months.
- Outcomes are generally excellent with appropriate treatment.
Controversies and Areas of Uncertainty
The 2 mm step-off rule derives from small Level IV series (Ertl 1988, Rapariz 1996). Some authors argue the location of the gap matters more than the absolute number - a step outside the principal weight-bearing zone may tolerate more displacement, whereas central plafond incongruity warrants reduction even near 2 mm. No randomised data exist to define a precise cut-off.
CT undeniably changes management (Eismann 2015), but it adds radiation and cost. A reasonable compromise is selective CT for any fracture that looks displaced, intra-articular, or triplane on plain films, while truly non-displaced extra-articular patterns may be followed radiographically. Practice varies by centre.
Several series report success with closed or percutaneous fixation under fluoroscopic and even arthroscopic control, avoiding open arthrotomy. Critics counter that the articular surface cannot be verified to within 2 mm without direct or CT-confirmed visualisation. The decision hinges on surgeon experience and intra-operative imaging quality.
MRI avoids radiation and shows the physeal cartilage and ligaments, and some paediatric centres prefer it. However CT remains faster, more available, and better for bony step-off measurement and screw planning. The radiation-versus-availability trade-off is unsettled, particularly in younger patients.
State the mainstream position (CT for displaced/intra-articular patterns, ORIF for over 2 mm step), then acknowledge the nuance: the threshold is evidence-light, fragment location matters, and percutaneous techniques are a legitimate alternative in experienced hands. Examiners reward candidates who know where the evidence is soft.
Evidence Base
- 15 children (mean age 13 years); triplane represented 6% of 237 consecutive physeal ankle fractures
- Tomography redefined the anatomy - a medial epiphyseal/malleolar fragment plus a lateral fragment carrying posterior metaphysis
- 13 of 15 treated closed; 3 of 14 showed premature symmetrical physeal closure with under 0.5 cm shortening and no angular deformity
- 23 patients reviewed; 11 of 15 anatomically confirmed cases were 3-fragment patterns
- Plain radiographs alone did not accurately demonstrate fracture configuration
- Residual displacement of 2 mm or more after reduction was associated with a less than optimum result unless the fragment lay outside the weight-bearing zone
- 35 patients reviewed; CT required because plain films did not accurately show configuration
- Closed reduction attempted first; failure to obtain or maintain reduction was the indication for surgery
- Degenerative change at over 5 years was seen only when reduction left more than 2 mm of displacement
- 5 raters assessed 25 triplane fractures with radiographs alone then with CT
- Adding CT moved displacement across the 2 mm threshold in 39% of ratings and changed the treatment decision (non-operative to operative) in 27%
- Rapariz classification reliability improved from poor (kappa 0.17) to moderate (kappa 0.41) with CT
- Narrative review: triplane fractures are 5-10% of paediatric intra-articular ankle injuries, typically age 12-15, slightly more common in boys
- Result of asymmetric distal tibial physeal closure over ~18 months
- Non-displaced fractures cast; displaced fractures need ORIF to within 2 mm via anterolateral or anteromedial approach
- Retrospective series identifying 10 atypical triplane patterns, including an extra-articular variant with an anteromedial epiphyseal sleeve fragment
- Closed reduction and percutaneous screw fixation gave no long-term complications
- Average return to sport 5.2 months; full range of motion regained by ~13 weeks
Exam Viva Scenarios
Practise clinical reasoning and management decisions out loud
“14-year-old girl twisted her ankle playing netball. X-ray shows an anterolateral epiphyseal fragment at the distal tibia. What is your assessment and management?”
“Same patient - CT shows an anterolateral epiphyseal fragment, a posterolateral metaphyseal spike, and the medial epiphysis is attached to the metaphysis. What is this pattern and how would you treat it?”
“CT shows an anterolateral epiphyseal fragment, a SEPARATE medial epiphyseal fragment, and a posterolateral metaphyseal fragment. How does this change your approach?”
MCQ Practice Points
Q: In what order does the distal tibial physis close? A: Central, Medial, Lateral (CML) - this asymmetric closure creates transitional fractures.
Q: A Tillaux fracture is which Salter-Harris type? A: Type III - involves the physis and epiphysis only.
Q: A Triplane fracture is which Salter-Harris type? A: Type IV - involves metaphysis, physis, and epiphysis.
Q: What imaging modality is essential for transitional fractures? A: CT scan - determines 2-part vs 3-part pattern and measures articular step-off.
Q: What is the threshold for operative treatment in transitional fractures? A: Greater than 2mm of articular step-off on CT.
Q: Why is growth arrest less concerning in transitional fractures? A: They occur near skeletal maturity - any growth arrest is rarely clinically significant.
Guidelines, Registries & Global Practice
Global epidemiology:
- Triplane fractures account for approximately 5-10% of paediatric intra-articular ankle injuries (Schnetzler & Hoernschemeyer 2007); juvenile Tillaux is rarer.
- Peak age 12-15 years, with triplane tending to occur slightly younger than Tillaux because more of the physis remains open.
- Slight male predominance; mechanism is external rotation across a narrow window of asymmetric physeal closure, so true incidence is similar worldwide where physeal maturation is comparable.
Side-by-side guidance (no formal RCT-based guideline exists - recommendations are consensus/textbook-derived):
| Source / Region | Imaging stance | Operative threshold | Emphasis |
|---|---|---|---|
| AAOS / JAAOS reviews (US) | CT for displaced or intra-articular patterns | ORIF if step over 2 mm | Anterolateral or anteromedial approach, screw fixation |
| BOA / BOAST principles (UK) | Cross-sectional imaging when surgery contemplated; senior decision-maker | Restore articular congruity | Definitive care in unit with paediatric expertise |
| AO Foundation (global) | CT for fragment mapping and pre-op planning | Anatomic joint reduction; lag screw fixation | Respect closing physis; avoid hardware across open lateral physis |
| EFORT / European consensus | CT to define 2- vs 3-part configuration | Reduce to under 2 mm; closed/percutaneous if achievable | Minimise soft-tissue insult, early mobilisation |
- Paediatric physeal ankle fractures are not implant-survival registry topics (these are not arthroplasty), so NJR/AOANJRR/AJRR data do not apply.
- Evidence is therefore single-centre Level III-IV series and reviews, not registry datasets - candidates should know the evidence base is comparatively thin.
- High-resource: routine CT, image-intensifier-guided or arthroscopic-assisted percutaneous screws, day-case ORIF.
- Limited-resource: reliance on good mortise radiographs and closed reduction; CT reserved for clearly displaced cases; cast immobilisation more often accepted when CT is unavailable.
Counselling points (globally applicable):
- Explain that growth arrest is unlikely to be clinically significant because the patient is near skeletal maturity.
- Emphasise that the goal is articular congruity, and that displacement may be greater on CT than on plain films.
- Consent should cover the small risks of stiffness, superficial peroneal nerve irritation, and the possibility of converting a closed plan to open reduction.
Self-Assessment Quiz
KEY FACTS
- CML physeal closure pattern
- Tillaux = SH-III
- Triplane = SH-IV
- Age 12-15 years
IMAGING
- CT is mandatory
- X-rays underestimate displacement
- Determine 2-part vs 3-part
- Measure articular step-off
TREATMENT THRESHOLD
- Greater than 2mm step = surgery
- Less than 2mm = cast with monitoring
- Weekly X-rays for first 2-3 weeks
- CT measurement is the gold standard
SURGICAL APPROACH
- Tillaux: anterolateral
- 2-part triplane: lateral
- 3-part triplane: may need medial too
- Epiphyseal screws parallel to joint
PROGNOSIS
- Excellent with anatomic reduction
- Growth arrest rarely significant
- Low arthritis risk if reduced
- Return to sport 3-4 months
KEY EVIDENCE
- 2mm threshold (Ertl 1988)
- CT changes management in 27% (Eismann 2015)
- Triplane described by Cooperman/Spiegel 1978
- Focus on articular reduction