Segond Fractures

Segond fractures are small avulsion fractures of the lateral tibial plateau, representing avulsion of the anterolateral ligament (ALL). They are pathognomonic for ACL tears, with 75-100% association. The fracture itself is small and non-articular, but its presence indicates significant rotational instability.

Mechanism of Injury

Classic mechanism: Same as ACL injury

• Non-contact: Cutting/pivoting on planted foot with knee near extension, valgus collapse
• Contact: Direct blow causing valgus/hyperextension
• Internal rotation: Combined with valgus and extension
• Peak force: Near full extension with valgus and internal rotation

The anterolateral ligament (ALL) is a secondary stabilizer to internal rotation. When the ACL tears, the ALL experiences excessive force and avulses from the lateral tibial plateau, creating the Segond fracture.

Epidemiology

• Incidence: 9-12% of ACL tears have Segond fracture
• Age: Peak 20-30 years (athletic population)
• Gender: Male predominance (2:1 ratio)
• Laterality: Usually unilateral
• Associated injuries: ACL tear (75-100%), lateral meniscal tear (30-40%), MCL injury (20-30%)

Anterolateral Ligament (ALL) Anatomy

The anterolateral ligament (ALL) is a distinct ligament structure:

• Origin: Lateral femoral epicondyle (proximal and posterior to LCL origin)
• Insertion: Lateral tibial plateau (anterolateral aspect, 5mm below joint line)
• Course: Oblique, anterior to LCL
• Function: Secondary stabilizer to internal rotation
• Relationship: Works with ACL to resist rotational instability

Discovery: The ALL was formally described in 2013, though Segond described the fracture in 1879. The ligament was previously thought to be part of the iliotibial band.

Pathophysiology

ACL injury mechanism:

• Valgus + internal rotation + extension
• ACL tears first (primary restraint)
• ALL experiences excessive force
• ALL avulses from lateral tibial plateau
• Creates Segond fracture

Why ALL avulses:

• ALL is weaker than ACL
• Excessive internal rotation force
• Bone (tibial plateau) is stronger than ligament-bone interface
• Avulsion occurs at insertion site

High-grade pivot shift:

• Segond fracture indicates more severe rotational instability
• ALL avulsion = loss of secondary rotational restraint
• Results in higher-grade pivot shift than isolated ACL tears

History

Mechanism: Same as ACL injury

• Cutting/pivoting on planted foot
• Knee near extension with valgus collapse
• "Pop" or "snap" sensation
• Immediate pain and swelling
• Inability to continue activity

Symptoms:

• Immediate pain and swelling
• Knee "giving way" (instability)
• Inability to bear weight
• Locking (if meniscal injury)

Physical Examination

Inspection:

• Knee effusion (hemarthrosis)
• Antalgic gait
• Knee held in slight flexion

Palpation:

• Tenderness over lateral tibial plateau (Segond fracture site)
• Joint line tenderness (if meniscal injury)
• MCL tenderness (if MCL injury)

Range of Motion:

• Limited flexion (pain, effusion)
• Limited extension (pain, effusion)

Ligament Testing:

• Lachman test: Positive (anterior translation)
• Anterior drawer: Positive (anterior translation)
• Pivot shift: Positive (rotational instability) - high-grade with Segond fracture
• Valgus stress: May be positive (if MCL injured)

Associated Injuries

• ACL tear: 75-100% (most common)
• Lateral meniscal tear: 30-40% (posterolateral)
• MCL injury: 20-30%
• Bone bruises: Posterolateral tibial plateau, lateral femoral condyle (kissing contusion)
• Cartilage injury: Lateral femoral condyle (30-40%)

ACL Graft Failure

5-10% incidence:

• Cause: High-grade pivot shift, young age, inadequate reconstruction
• Prevention: Consider LET for high-grade pivot shift, anatomic ACL reconstruction
• Management: Revision ACL reconstruction with LET

Residual Pivot Shift

10-15% incidence:

• Cause: Inadequate ACL reconstruction, no LET for high-grade pivot shift
• Prevention: Anatomic ACL reconstruction, consider LET for high-grade cases
• Management: Revision ACL reconstruction with LET if symptomatic

Segond Fracture Nonunion

Less than 5% incidence:

• Cause: Large fragment, displacement, inadequate fixation
• Prevention: Fixation if large fragment (rare)
• Management: Fixation if symptomatic (rare)

Immediate Postoperative

• Immobilization: Hinged knee brace locked in extension (2-4 weeks)
• Weight bearing: Non-weight bearing initially (2-3 weeks)
• ROM: Begin passive ROM at 2-4 weeks (unlock brace)
• PT: Quadriceps sets, straight leg raises (immediate)

Rehabilitation Protocol

Weeks 0-2:

• Brace locked in extension
• Non-weight bearing
• Quadriceps sets, straight leg raises
• Ice and elevation

Weeks 2-4:

• Unlock brace for passive ROM (0-90 degrees)
• Progressive weight bearing (partial to full)
• Stationary bike (when ROM allows)
• Continue quadriceps strengthening

Weeks 4-6:

• Full ROM
• Full weight bearing
• Progressive strengthening
• Balance and proprioception

Weeks 6-12:

• Sport-specific training
• Return to sport (when strength and ROM normal)
• Continue PT for 3-6 months

Return to Sport

Criteria:

• Full ROM (equal to contralateral)
• Quadriceps strength greater than 90% of contralateral
• No instability (negative Lachman, pivot shift)
• Functional testing passed (hop test, agility)

Timeline: Usually 6-9 months postoperatively.

Overall Outcomes

ACL reconstruction outcomes:

• Success rate: 85-90% (same as standard ACL reconstruction)
• Functional outcomes: 80-85% return to pre-injury level
• Complications: 10-15% (graft failure, residual pivot shift)

Segond fracture outcomes:

• Healing: Usually heals without fixation (fragment is small)
• Nonunion: Less than 5% (rare, usually asymptomatic)
• Fixation: Rarely needed

Functional Outcomes

Return to sport:

• Timeline: 6-9 months postoperatively
• Rate: 80-85% return to pre-injury level
• Factors: Age, sport level, rehabilitation compliance, LET use

Functional testing:

• Quadriceps strength: 90%+ of contralateral
• No instability (negative Lachman, pivot shift)
• Full ROM

Long-Term Prognosis

Graft failure risk:

• Standard ACL reconstruction: 5-10%
• With LET: 3-5% (reduced failure rate)
• High-grade pivot shift without LET: 10-15% (higher failure rate)

Residual pivot shift:

• Standard ACL reconstruction: 10-15%
• With LET: 5-10% (reduced pivot shift)
• High-grade cases without LET: 15-20% (higher residual pivot shift)

Factors Affecting Outcomes

Positive factors:

• Anatomic ACL reconstruction
• LET for high-grade pivot shift
• Complete rehabilitation
• Early ROM (2-4 weeks)

Negative factors:

• High-grade pivot shift without LET
• Inadequate ACL reconstruction
• Incomplete rehabilitation
• Early return to sport

Prevention

Primary prevention:

• Proper landing technique (knee flexion, not hyperextension)
• Strength training (quadriceps, hamstrings)
• Balance and proprioception training
• Sport-specific conditioning

Secondary prevention (after injury):

• Complete rehabilitation before return to sport
• Bracing (controversial - may not prevent reinjury)
• Continued strength and conditioning

Return to Sport Criteria

Clinical:

• Full ROM (equal to contralateral)
• Quadriceps strength greater than 90% of contralateral
• No effusion
• No instability (negative Lachman, pivot shift)

Functional:

• Single-leg hop test (greater than 90% of contralateral)
• Agility testing passed
• Sport-specific drills completed

Timeline: Usually 6-9 months postoperatively, depending on sport and level.