Distal Tibial Physeal Injuries
Navigating the Transitional Zone
Fracture Types
Critical Must-Knows
- Asymmetric Closure: Creates transitional fractures.
- Tillaux: SH III, anterolateral epiphyseal fragment.
- Triplane: SH IV pattern, three-plane fracture.
- 2mm Rule: Greater than 2mm articular step-off needs ORIF.
- Growth Arrest is Less Common: Occurs near skeletal maturity.
Examiner's Pearls
- "Know the closure pattern (Central-Medial-Lateral)
- "Tillaux vs Triplane distinction
- "CT is essential for transitional fractures
- "ORIF if step-off greater than 2mm
Clinical Imaging
Imaging Gallery
The 2mm Rule
ORIF Threshold
greater than 2mm articular displacement mandates surgery. Intra-articular malunion leads to arthritis. Anatomical reduction is the goal.
Imaging Trap
CT is essential. Standard X-rays underestimate displacement in transitional fractures (3D geometry).
Tillaux vs Triplane
| Feature | Tillaux | Triplane |
|---|---|---|
| Type III | Type IV | |
| Single plane (horizontal) | Three planes | |
| Anterolateral epiphysis | Variable (2-4 part) | |
| 12-15 years | 12-15 years | |
| ORIF if greater than 2mm | ORIF if greater than 2mm |
Physeal Closure Pattern
Memory Hook:CML - Central, Medial, Lateral (like a leukemia you don't want).
Tillaux Features
Memory Hook:AIT - Anterolateral, Intra-articular, Transitional.
Triplane Features
Memory Hook:TFC - Three planes, Four parts, CT essential.
Overview/Epidemiology
Distal Tibial Physeal Injuries occur in two main contexts:
- Standard Salter-Harris Fractures: Similar to other physes.
- Transitional Fractures (Tillaux, Triplane): Unique to adolescents due to asymmetric physeal closure.
- Epidemiology:
- Transitional fractures occur between ages 12-15 years.
- More common in boys (due to later physeal closure).
- Standard SH injuries can occur at any age.
- Mechanism:
- External rotation is the most common mechanism for transitional fractures.
- The AITFL (anterior inferior tibiofibular ligament) avulses the anterolateral epiphysis.
Anatomy and Pathomechanics
Physeal Closure Pattern The distal tibial physis closes asymmetrically over 18 months:
- Central: First to close (approximately age 12-14).
- Medial (Anteromedial): Closes next.
- Lateral (Posterolateral): Last to close (approximately age 14-16).
Tillaux Fracture
- The lateral physis is still open when the external rotation force occurs.
- The AITFL attaches to the anterolateral epiphysis.
- External rotation avulses the anterolateral fragment (SH Type III).
Triplane Fracture
- More complex pattern with fracture in three planes.
- Sagittal (through the epiphysis - like Tillaux).
- Horizontal (through the physis).
- Coronal (through the metaphysis - like SH II).
- Can be 2-part, 3-part, or 4-part.
Classification Systems
Standard Salter-Harris
Applied to the Distal Tibia (non-transitional):
Type I: Through the physis only. May be occult.
Type II: Most common in younger children. Metaphyseal fragment.
Type III/IV: Intra-articular. Require anatomical reduction.
Clinical Assessment
History:
- Mechanism: Twisting (external rotation)? Inversion? Direct trauma?
- Age: Transitional fractures occur at ages 12-15.
Physical Exam:
- Inspection: Swelling, ecchymosis, deformity.
- Palpation: Tenderness over the physis (anterolateral for Tillaux).
- ROM: Limited by pain.
- Neurovascular: Document status.
- Fibula: Check for associated fibular fracture.
Investigations
Imaging:
- X-ray (AP, Lateral, Mortise): Standard. May show widening or fragment.
- CT Scan with 3D Reconstruction: ESSENTIAL for transitional fractures. X-ray underestimates displacement.
- Allows measurement of articular step-off and surgical planning.
Management Algorithm
Non-Displaced (Step-off Less Than 2mm)
- Below-Knee Cast: For 4-6 weeks.
- Non-weight bearing initially.
- Close follow-up with X-rays at 1-2 weeks.
Surgical Techniques
Closed Reduction and Percutaneous Fixation (Tillaux)
Indications: Displaced Tillaux amenable to closed reduction.
Technique: Under fluoroscopy, internally rotate the foot to reduce the anterolateral fragment. If anatomical reduction is achieved (confirmed on mortise and lateral), pass a 4.0mm cannulated screw from anterolateral to posteromedial under fluoroscopic guidance, staying within the epiphysis and parallel to the joint.
Post-op: Below-knee cast for 4-6 weeks. Post-op CT to confirm reduction.
Key Surgical Points
- Always obtain post-op CT to confirm reduction.
- Screw fixation is superior to K-wires for compression.
- Screw placement should be parallel to the joint and avoid crossing the physis.
Complications
| Complication | Rate | Prevention/Management |
|---|---|---|
| Malunion | Low if ORIF is done | Anatomical reduction. Post-op CT confirmation. |
| Post-Traumatic Arthritis | Risk with greater than 2mm step-off | Anatomical reduction. |
| Growth Arrest | Low (fractures occur near maturity) | Monitor if significant growth remaining. |
| Wound Complications | Rare | Careful soft tissue handling. |
| Hardware Irritation | Occasional | May require screw removal. |
Postoperative Care
- Immobilization: Below-knee cast for 4-6 weeks.
- Weight Bearing: Non-weight bearing initially, then WBAT at 4-6 weeks.
- Post-Op CT: Essential to confirm reduction, especially for triplane.
- Follow-Up: At 2 weeks (wound check), 6 weeks (cast removal), and 3 months.
- Growth Surveillance: Less critical than at other physes due to near-skeletal maturity.
Outcomes/Prognosis
- Non-Displaced: Excellent outcomes with casting.
- Displaced (Anatomically Reduced): Good outcomes. Low arthritis risk.
- Malunited (Greater Than 2mm): Risk of post-traumatic arthritis.
- Growth Arrest: Uncommon because these fractures occur near skeletal maturity. If significant growth remains, monitor.
Evidence Base
- Original description of triplane fracture
- Three planes of fracture
- Classification into 2, 3, and 4-part types
- Outcome of Tillaux and Triplane fractures
- Anatomical reduction leads to good outcomes
- Greater than 2mm displacement leads to arthritis
- CT imaging for transitional fractures
- X-ray underestimates displacement
- CT should be routine for transitional fractures
- Outcomes of distal tibial physeal fractures
- Low growth arrest rate
- Good functional outcomes
- Comparison of treatment methods
- ORIF for greater than 2mm displacement
- Casting for minimally displaced fractures
Viva Scenarios
Practice these scenarios to excel in your viva examination
The Tillaux Fracture
"14-year-old with ankle pain after a twisting injury playing soccer. X-ray shows an anterolateral fragment of the distal tibial epiphysis. CT shows 3mm of articular step-off."
This is a **Juvenile Tillaux fracture** - a Salter-Harris Type III fracture of the anterolateral distal tibial epiphysis. The 3mm step-off exceeds the 2mm threshold. Management: **ORIF**. I would attempt closed reduction under fluoroscopy first. If successful, I would place a percutaneous cannulated screw. If closed reduction fails, I would perform an open reduction via an anterolateral approach and fix with a screw. Post-op CT to confirm reduction. Cast for 4-6 weeks.
The Triplane Fracture
"13-year-old with ankle injury after a fall. X-ray shows a fracture through the physis with a metaphyseal fragment. CT shows a 3-part triplane fracture with 4mm step-off."
This is a **Triplane fracture** - a Salter-Harris Type IV pattern with fracture lines in three planes. The 4mm step-off is unacceptable. Management: **ORIF**. I would attempt closed reduction, but given the complexity (3-part), open reduction is likely needed. I would use an anterolateral and possibly anteromedial approach to visualize all fragments. Fix with cannulated screws. Post-op CT is mandatory. Cast for 4-6 weeks.
Non-Displaced Tillaux
"15-year-old with ankle pain. X-ray shows a probable Tillaux fracture. CT shows 1.5mm of articular step-off."
This is a **non-displaced Tillaux fracture**. The step-off is less than 2mm, which is acceptable. Management: **Below-knee cast** for 4-6 weeks. Non-weight bearing initially. Close follow-up with X-rays at 1-2 weeks to ensure no displacement. No ORIF is needed unless displacement increases.
Growth Arrest After Tillaux
"14-year-old, 1 year after a Tillaux fracture. Now has slight valgus of the ankle and 0.5cm LLD."
This suggests **growth arrest** from the Tillaux fracture, though this is uncommon because the injury occurs near skeletal maturity. I would obtain a **scanogram** and **bone age** to estimate remaining growth. If the child is nearly skeletally mature, the LLD and angular deformity may not worsen significantly. If significant growth remains, I would consider **bar excision** (if less than 50%) or guided growth. The small LLD may not require treatment. The valgus may need monitoring or eventual osteotomy if it progresses.
MCQ Practice Points
Anatomy MCQ
Q: Which part of the distal tibial physis closes first? A: Central. Then medial, then lateral (CML pattern).
Classification MCQ
Q: A Tillaux fracture is which Salter-Harris type? A: Type III. It involves the physis and epiphysis only.
Classification MCQ
Q: A Triplane fracture is which Salter-Harris type? A: Type IV. It involves the metaphysis, physis, and epiphysis.
Treatment MCQ
Q: What is the threshold for operative treatment in transitional fractures? A: Greater than 2mm of articular step-off.
Closure Pattern MCQ
Q: In what order does the distal tibial physis close? A: Central, Medial, Lateral (CML) - this asymmetric closure creates transitional fractures.
Imaging MCQ
Q: What imaging modality best defines transitional fracture anatomy? A: CT scan - essential to determine fracture pattern (2-part vs 3-part triplane) and articular step-off.
Australian Context
- CT Scanning: Widely available and should be routine for transitional fractures.
- Surgical Approach: ORIF is readily accessible in most centers.
- Follow-Up: Growth surveillance is less critical than at other physes due to near-maturity.
DISTAL TIBIAL PHYSEAL INJURIES
High-Yield Exam Summary
KEY FACTS
- •45% Tibial Growth
- •Central-Medial-Lateral Closure
- •Tillaux = SH III
- •Triplane = SH IV
TILLAUX
- •Anterolateral fragment
- •AITFL avulsion
- •External rotation
- •Age 12-15
TRIPLANE
- •3 Planes (S/H/C)
- •2-4 Parts
- •CT Essential
- •Age 12-15
TREATMENT
- •Less than 2mm: Cast
- •Greater than 2mm: ORIF
- •Post-Op CT
- •4-6 Week Immob
Deep Dive: CT Imaging for Transitional Fractures
Why is CT Essential?
- X-rays only show two planes. Transitional fractures are three-dimensional.
- CT accurately measures articular step-off (the critical 2mm threshold).
- CT identifies the number of fragments (2-part vs 3-part vs 4-part triplane).
- 3D reconstruction aids surgical planning.
What to Look For on CT:
- Articular step-off: Measure on axial and sagittal images.
- Fracture pattern: Identify all fragments.
- Physeal involvement: Extent of physeal injury.
- Fibular injury: Often associated.
Post-Op CT:
- Mandatory to confirm anatomical reduction.
- Repeat if there is any concern about reduction quality.
Self-Assessment Quiz
Parent's Guide: Understanding Transitional Fractures
What is a transitional fracture? A transitional fracture is a type of ankle fracture that occurs in adolescents as the growth plate is closing. The growth plate does not close all at once - it closes in stages. During this transition, certain fracture patterns can occur.
What are Tillaux and Triplane fractures? These are the two main types of transitional fractures. They involve the ankle joint, and if the fracture is significantly displaced, surgery is needed to prevent arthritis.
How is displacement measured? A CT scan is used to measure exactly how much the fracture has shifted. If the shift is more than 2mm, surgery is usually recommended.
What is the treatment?
- If less than 2mm shifted: A cast for 4-6 weeks.
- If more than 2mm shifted: Surgery to realign the bones (screws are often used).
What is the outcome? Most patients do very well. Because these fractures occur near the end of growth, growth problems are uncommon.
Rehabilitation Protocol
Phase 1: Immobilization (0-6 weeks)
- Below-knee cast.
- Non-weight bearing initially.
- Toe wiggling and calf pumps.
Phase 2: Early Mobilization (6-10 weeks)
- Cast removal.
- Ankle ROM exercises (dorsiflexion, plantarflexion).
- Progressive weight bearing.
Phase 3: Strengthening (10-16 weeks)
- Resistance exercises (theraband).
- Proprioception and balance training.
- Gait normalization.
Phase 4: Return to Sport (4-6 months)
- Sport-specific training.
- Full ROM and strength.
- Clearance by surgeon.
Differential Diagnosis
Adolescent Ankle Pain After Trauma:
- Tillaux Fracture: Anterolateral fragment on X-ray/CT.
- Triplane Fracture: Complex pattern on CT.
- Lateral Malleolus Fracture: Tender over fibula.
- Syndesmotic Injury: Tender over syndesmosis, squeeze test positive.
- Standard SH Fracture: Physeal widening.
- Ankle Sprain: Tender over ATFL. X-ray normal.
Additional Self-Assessment Questions
Surgical Pearls
Tillaux ORIF
- Anterolateral approach between EHL and EDL.
- Identify the fracture line arthroscopically or by direct vision.
- Reduce anatomically and hold with a K-wire.
- Place 4.0mm cannulated screw from anterolateral to posteromedial.
- Confirm reduction on fluoroscopy and with post-op CT.
Triplane ORIF
- May need combined anterolateral and anteromedial approaches.
- Reduce the epiphyseal fragment first (articular priority).
- Then reduce the metaphyseal component.
- Fix epiphyseal fragment with parallel screw.
- Metaphyseal fragment may need a separate screw.
- Post-op CT is mandatory.
Avoiding Common Pitfalls
- Do not rely on X-ray alone to assess displacement.
- Always get a CT before deciding on treatment.
- Post-op CT confirms reduction; do not skip this step.
Comparison: Distal Tibia vs Other Physes
Distal Tibia vs Distal Femur
| Feature | Distal Tibia | Distal Femur |
|---|---|---|
| 45% of tibia | 70% of femur | |
| Low (near maturity) | High (30-50%) | |
| Tillaux, Triplane | Rare | |
| Articular reduction | Physis protection |