Proximal Tibial Physeal Injuries
High Risk, High Vigilance
Salter-Harris Classification
Critical Must-Knows
- Vascular Risk: Popliteal artery is tethered. Hyperextension injuries are highest risk.
- Compartment Syndrome: Common secondary to vascular injury or direct trauma.
- Anatomical Reduction: Essential for all types.
- Growth Arrest: 20-30% risk. Follow for at least 2 years.
- Ligaments Protect Physis: Injuries often associated with high energy.
Examiner's Pearls
- "Check pulses and compartments carefully
- "Low threshold for angiography
- "Valgus stress tests ligament vs physis
- "Follow for growth disturbance
Vascular Emergency Risk
The proximal tibia has the HIGHEST vascular injury risk of pediatric physeal fractures around the knee.
- The popliteal artery is tethered as it passes under the soleal arch.
- In hyperextension injuries, the artery can be stretched, intima can tear, or thrombosis can occur.
- An absent pulse after injury requires URGENT assessment (ABI, CTA, vascular surgery).
- Compartment syndrome commonly follows vascular injury (reperfusion or direct ischemia).
Proximal Tibial Physis Key Facts
| Feature | Importance | Clinical Relevance |
|---|---|---|
| 55% of tibia, 25% of leg | Second highest in lower limb | |
| Popliteal artery tethered | Highest of knee physes | |
| 20-30% | Less than distal femur but significant | |
| Collateral ligaments attach to epiphysis | Relatively protected area |
Proximal Tibia Dangers
Memory Hook:VCG - The three dangers.
Evaluation Priorities
Memory Hook:PCN - Primary Check Neurovasc.
Management Principles
Memory Hook:RSS - Reduce, Stabilize, Surveil.
Overview/Epidemiology
Proximal Tibial Physeal Injuries are relatively uncommon due to the protected nature of the physis.
- Epidemiology:
- Account for less than 3% of all physeal injuries.
- Mean age 12-14 years.
- Boys are more commonly affected.
- Mechanism:
- Hyperextension: Highest vascular risk.
- Varus/Valgus Stress: May be mistaken for ligament injury.
- Direct Trauma: High-energy mechanisms (MVA, sports).
- Why Less Common?
- The medial and lateral collateral ligaments attach to the tibial epiphysis (below the physis), providing protection.
- Valgus stress that would injure the MCL in an adult may cause a proximal tibial physeal fracture in a child.
Anatomy and Pathomechanics
Physeal Anatomy
- The proximal tibial physis is an irregular physis with mamillary processes.
- It contributes 55% of tibial length (approximately 6mm/year).
- The tibial tubercle apophysis is contiguous with the proximal physis anteriorly.
Vascular Anatomy
- The popliteal artery passes close to the posterior aspect of the physis.
- It is tethered at the soleal arch (where it becomes the anterior and posterior tibial arteries).
- Hyperextension can stretch the artery over the posterior tibial metaphysis.
- Vascular injury risk is higher than distal femoral injuries.
Nerve Anatomy
- The common peroneal nerve winds around the fibular neck.
- It can be injured in varus injuries or direct trauma.
Classification Systems
Salter-Harris Classification
Type I: Through the physis only. May be occult on X-ray.
Type II: Most common (60%). Metaphyseal fragment (posterolateral or posteromedial).
Type III: Intra-articular. Usually tibial eminence avulsions are managed separately.
Type IV: Crosses all layers. High arrest risk. ORIF required.
Clinical Assessment
History:
- Mechanism: Hyperextension? Valgus stress? Direct blow?
- Neurovascular Symptoms: Numbness, cold foot, weakness?
Physical Exam:
- Inspection: Swelling, deformity, skin tenting, ecchymosis.
- Palpation: Tenderness over the proximal tibial physis.
- Neurovascular (CRITICAL): Popliteal pulse, DP, PT. Capillary refill. Peroneal nerve function.
- Compartments: Palpate all four leg compartments. Pain on passive stretch of toes is a key sign.
- Ligaments: Valgus stress may reveal physeal opening vs MCL laxity (physis is weaker in children).
Investigations
Imaging:
- X-ray (AP and Lateral): Standard. Include the knee and distal tibia.
- Stress Views: With caution. Under anesthesia if needed.
- CT Scan: For Type III/IV to map the fracture.
- MRI: If occult injury suspected or to assess ligaments.
Vascular Assessment:
- Ankle-Brachial Index (ABI): If pulses are asymmetric or diminished.
- Doppler Ultrasound: If equipment available.
- CT Angiography: If vascular injury suspected.
Management Algorithm
Non-Displaced / Minimally Displaced Fractures
- Long Leg Cast: Knee in slight flexion (20 degrees).
- Duration: 6 weeks.
- Close follow-up with weekly X-rays to monitor for displacement.
- Consider prophylactic pinning given the high stakes.
Surgical Techniques
Closed Reduction and Percutaneous Pinning
Indications: Displaced Type I/II with acceptable closed reduction.
Technique: Reduction under fluoroscopy. For hyperextension injuries, flex the knee and apply anterior force to the proximal fragment. Once reduced, pass 2-3 smooth K-wires from the metaphysis, crossing the fracture into the epiphysis. Diverge wires for stability. Cut flush or bury.
Post-op: Long leg cast for 6 weeks. Pin removal at 4-6 weeks.
Key Surgical Points
- Single reduction attempt to minimize physis damage.
- Document neurovascular status before and after every manipulation.
- Low threshold for fasciotomy if compartments are tense post-reduction.
Complications
| Complication | Rate | Prevention/Management |
|---|---|---|
| Vascular Injury | 2-7% | Vascular assessment. Urgent repair. |
| Compartment Syndrome | Variable | Low threshold for fasciotomy. |
| Growth Arrest | 20-30% | Anatomical reduction. Monitor long-term. |
| Angular Deformity | Common with partial arrest | Bar excision or osteotomy. |
| Leg Length Discrepancy | Common | Epiphysiodesis or lengthening. |
| Peroneal Nerve Palsy | Rare | Document pre-op. Avoid traction. |
Postoperative Care
- Immobilization: Long leg cast for 6 weeks minimum.
- Weight Bearing: Non-weight bearing initially.
- Pin Removal: 4-6 weeks.
- Vascular Monitoring: Close observation post-op for any vascular repair.
- Follow-Up Schedule:
- Weekly X-rays for first 2-3 weeks.
- 6-week X-ray (assess healing).
- 6-month and 12-month scanograms.
- Annual follow-up until skeletal maturity.
Outcomes/Prognosis
- Growth Arrest: Occurs in 20-30% of cases.
- Vascular Injury: If unrecognized, can lead to limb loss.
- Compartment Syndrome: Early fasciotomy leads to good outcomes.
- Functional Outcomes: Generally good if complications are managed promptly.
Evidence Base
- Review of proximal tibial physeal fractures
- Vascular injury in 7% of cases
- Higher in hyperextension injuries
- Growth arrest after proximal tibial physeal injuries
- Overall arrest rate 25%
- Higher with Type III/IV
- Popliteal artery injury in pediatric knee trauma
- Delayed diagnosis common
- Limb loss if not recognized early
- Management principles for proximal tibial fractures
- Importance of neurovascular assessment
- Anatomical reduction for intra-articular injuries
- Long-term outcomes of physeal injuries
- Proximal tibia has significant arrest potential
- Bar excision successful if less than 50%
Viva Scenarios
Practice these scenarios to excel in your viva examination
The Hyperextension Injury
"11-year-old cyclist thrown over handlebars. Hyperextension injury to the knee. Obvious deformity. Foot is cold and pale. No palpable DP pulse."
This is a **vascular emergency**. The mechanism (hyperextension) puts the popliteal artery at high risk. The cold, pale foot with absent pulse confirms vascular compromise. Immediate management: **Immediate reduction** to restore alignment (may restore flow). If pulses do not return, **urgent CTA** and **vascular surgery consultation**. The fracture should be stabilized (external fixation if needed) to protect the vascular repair. **Fasciotomy** is likely needed for reperfusion injury.
The Swollen Leg After Reduction
"Same patient. Vascular repair was successful. 6 hours later, the leg is tense and the child is in severe pain despite analgesia."
This is **compartment syndrome**, likely from reperfusion injury after revascularization. The tense leg and pain out of proportion are classic signs. There is no time for pressure measurements in this context. Management: **Urgent four-compartment fasciotomy**. The incisions are lateral (2cm anterior to fibula for anterior and lateral compartments) and medial (2cm posterior to the tibial border for superficial and deep posterior compartments). Leave wounds open with VAC or wet dressings.
The Valgus Stress Injury
"13-year-old tackled while playing football. Valgus force to the knee. Tender medially over the proximal tibia. X-ray shows widening of the proximal tibial physis medially."
This is a **Salter-Harris Type I or II proximal tibial physeal fracture** caused by valgus stress. In adults, this mechanism causes an MCL tear. In children, the physis is the weak link. Management: Closed reduction under anesthesia and **percutaneous pinning** with smooth K-wires. Post-op in a long leg cast. Counsel the family about the 20-30% risk of growth disturbance.
Growth Arrest After Proximal Tibial Injury
"9-year-old, 1 year post Type II proximal tibial physeal fracture. Now has progressive valgus of 12 degrees and 1.5cm LLD."
This is a **growth arrest** with a lateral physeal bar causing both angular deformity (valgus) and shortening. I would get an **MRI** to map the bar. If the bar is **less than 50%** and the child has more than 2 years of growth remaining, I would consider **bar excision** with fat interposition. A concurrent **corrective osteotomy** may be needed to address the existing valgus. If the bar is greater than 50%, I would proceed with **contralateral epiphysiodesis** and corrective osteotomy.
The Polytrauma Patient
"9-year-old MVA. Multiple injuries including a displaced proximal tibial physeal fracture. Hemodynamically stable after resuscitation."
After completing ATLS, I would assess the limb carefully for **neurovascular status**. Given the risk of popliteal artery injury, I would perform **closed reduction** urgently under fluoroscopy and **percutaneous pin fixation**. If there is any vascular concern, I would involve the vascular team immediately. Post-op in a long leg cast with close monitoring for compartment syndrome. This patient needs long-term growth surveillance.
The Nondisplaced Type I
"12-year-old with knee pain after football. Tender over the proximal tibial physis. X-ray shows subtle physeal widening medially."
This is a **Salter-Harris Type I proximal tibial physeal fracture**. Even though it is non-displaced, I would treat this with a **long leg cast** for 6 weeks. Given the high stakes of this location, I would consider **prophylactic percutaneous pinning** to prevent displacement. Close follow-up with weekly X-rays for the first 2-3 weeks. Counsel the family about the 20-30% risk of growth disturbance and arrange long-term surveillance.
MCQ Practice Points
Anatomy MCQ
Q: What percentage of tibial length does the proximal tibial physis contribute? A: 55%. This is the largest growth contributor in the tibia.
Vascular MCQ
Q: What vascular structure is at highest risk in proximal tibial physeal injuries? A: Popliteal Artery. It is tethered at the soleal arch.
Prognosis MCQ
Q: What is the approximate growth arrest rate for proximal tibial physeal fractures? A: 20-30%.
Treatment MCQ
Q: A child has a valgus stress injury with physeal widening. What does this represent? A: Physeal fracture (not MCL injury). The physis is weaker than the ligament in children.
Compartment Syndrome MCQ
Q: What is the most feared early complication after proximal tibial physeal injury? A: Compartment syndrome - requires low threshold for fasciotomy due to tight leg compartments.
Bar Excision MCQ
Q: When is physeal bar excision indicated for growth arrest? A: When the bar is less than 50% of physis width with at least 2 years of growth remaining.
Australian Context
- Transfer to Tertiary Centre: Any suspected vascular injury should be managed at a tertiary pediatric trauma centre.
- Vascular Surgery: 24/7 availability is essential.
- Compartment Syndrome: Low threshold for fasciotomy.
- Follow-Up: Long-term surveillance with scanograms.
PROXIMAL TIBIAL PHYSEAL INJURIES
High-Yield Exam Summary
KEY FACTS
- •55% Tibial Growth
- •25% Leg Length
- •Highest Vascular Risk
- •20-30% Arrest Risk
DANGERS
- •Popliteal Artery
- •Compartment Syndrome
- •Peroneal Nerve
- •Growth Arrest
TREATMENT
- •Anatomical Reduction
- •Smooth K-Wire Pinning
- •ORIF for Type III/IV
- •6+ Week Immobilization
SURVEILLANCE
- •Weekly X-rays Early
- •6-Month Scanogram
- •Annual to Maturity
- •Low Threshold Angio
Deep Dive: Popliteal Artery Injury
Why is it at Risk?
- The popliteal artery is tethered both proximally (at the adductor hiatus) and distally (at the soleal arch).
- In hyperextension injuries, the artery is stretched over the posterior tibial metaphysis.
- The artery can be lacerated, intima torn (leading to thrombosis), or go into spasm.
Signs of Vascular Injury
- Hard Signs: Absent pulse, expanding hematoma, bruit, active bleeding.
- Soft Signs: Diminished pulse, proximity to major vessel, history of hemorrhage.
Management
- Any hard sign = urgent exploration.
- Soft signs = ABI (less than 0.9 is concerning) and CTA.
- If confirmed injury: Reduce fracture, stabilize with external fixation, vascular repair.
- Fasciotomy is often needed for reperfusion injury.
Golden Time
- 6 hours of warm ischemia is the limit before irreversible muscle necrosis.
- Earlier is better.
Self-Assessment Quiz
Parent's Guide: Understanding Proximal Tibial Injuries
What is the proximal tibial growth plate? The proximal tibia (shinbone near the knee) has a growth plate that is responsible for about 55% of the shinbone's growth. Injury here is serious because it can affect how your child's leg grows.
Why is this injury particularly concerning? The major artery and nerve that supply the leg pass very close to this growth plate. Injury here can sometimes damage these structures, which requires urgent treatment.
What signs should we watch for?
- A cold or pale foot.
- Numbness or tingling in the foot.
- Severe pain that is not relieved by medication.
- A calf that feels very tight or hard.
If any of these occur, seek medical attention immediately.
What follow-up is needed? Regular X-rays for at least 2 years to monitor the growth plate.
Rehabilitation Protocol
Phase 1: Immobilization (0-6 weeks)
- Long leg cast with knee in slight flexion.
- Non-weight bearing.
- Toe wiggling and calf pumps.
Phase 2: Early Mobilization (6-10 weeks)
- Cast removal when healed.
- Hinged knee brace initially.
- Progressive weight bearing.
- Active and passive ROM.
Phase 3: Strengthening (10-16 weeks)
- Progressive resistance exercises.
- Closed kinetic chain exercises.
- Proprioception training.
Phase 4: Return to Sport (4-6 months)
- Sport-specific training.
- Full ROM and strength.
- Clearance by surgeon.
Differential Diagnosis
Knee Pain After Trauma:
- Proximal Tibial Physeal Fracture: Point tenderness over the physis. Physeal widening on X-ray.
- MCL Tear: Rare in children. Valgus stress test is positive.
- ACL Tear / Tibial Eminence Avulsion: Hemarthrosis. Extension block.
- Tibial Tubercle Avulsion: Tender over the tubercle. Extension weakness.
- Distal Femoral Physeal Fracture: Tenderness over the distal femoral physis.
- Patellar Dislocation: Apprehension sign. May be reduced.
Additional Self-Assessment Questions
Surgical Pearls
Reduction Technique
- Apply longitudinal traction with the knee slightly flexed.
- For hyperextension injuries (posterior displacement of the proximal metaphysis), flex the knee and push the metaphysis anteriorly.
- Avoid excessive force. Single gentle reduction attempt is preferred.
Pinning Technique
- Enter from the lateral and medial metaphysis, superior to the physis.
- Direct the wires distally, crossing the fracture into the epiphysis.
- Diverge the wires for stability (3-point fixation concept).
- Image in two planes (AP and lateral) to confirm position.
- Avoid the tibial tubercle apophysis and the articular surface.
Post-Reduction Checks
- Check neurovascular status immediately after reduction.
- Document pulses both before and after manipulation.
- Confirm reduction on X-ray before leaving the operating room.
- Low threshold for fasciotomy if there is any compartment concern.
Comparison: Proximal Tibia vs Other Physes
Proximal Tibia vs Distal Femur
| Feature | Proximal Tibia | Distal Femur |
|---|---|---|
| Less than 3% of physeal injuries | 1-5% of physeal injuries | |
| 55% of tibia | 70% of femur | |
| Highest of all knee physes | High but lower than prox tib | |
| 20-30% | 30-50% |