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: Seen on injury radiographs in roughly 7-9% of ACL tears; up to about 15% when healed lesions are included (Slagstad et al, AJSM 2020)
• Age: Peak 20-30 years (athletic population); skiing mechanisms over-represented
• Gender: Male predominance (approximately 2:1)
• Laterality: Usually unilateral
• Associated injuries: ACL tear (the lesion is highly specific for ACL injury), lateral meniscal tear (around 30-40%), MCL injury (around 20-30%)

The phrase "pathognomonic" is traditional teaching: a Segond fracture is highly specific for ACL injury and should be treated as an ACL tear until proven otherwise, but rare isolated cases without ACL rupture do exist.

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

A small fleck of bone around the proximal tibia is the radiographic crux. Each fleck points to a different ligament and a different associated injury, so localising it precisely is the exam-winning step.

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 rupture risk (STABILITY trial, young high-risk patients, 2 years):

• Isolated hamstring ACL reconstruction: 11%
• ACL reconstruction + LET: 4% (number needed to treat 14.3)
• Composite clinical failure (rupture or residual rotatory laxity): 40% vs 25% favouring LET

Residual rotatory laxity:

• Persistent anterolateral rotatory laxity correlates with poorer outcomes and graft failure; adding LET reduces the composite failure that includes residual rotatory laxity.
• A Segond fracture itself does not independently raise revision risk (Slagstad et al, AJSM 2020) - it flags the high-risk phenotype rather than causing failure.

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.

Global Epidemiology

• Segond fracture is seen on injury radiographs in roughly 7-9% of ACL tears; including healed lesions the figure rises to about 15% (Slagstad et al, AJSM 2020).
• Demographics mirror ACL injury: young, athletic, pivoting/cutting sports and skiing; the Segond subgroup is associated with downhill skiing mechanisms.
• The lesion is a radiographic surrogate, not a separate disease - so there is no dedicated guideline for "Segond fracture"; guidance is embedded within ACL and anterolateral-complex recommendations.

Side-by-Side Guidance (ACL / Anterolateral Complex)

Registry & Trial Evidence

• High-quality randomised data (STABILITY, Getgood et al 2020) and the SANTI group series (Sonnery-Cottet) underpin lateral augmentation in young high-risk patients; this is the population a Segond fracture identifies.
• ACL-reconstruction registries (e.g. the Scandinavian Knee Ligament registries - Norwegian, Swedish, Danish - and the UK NLR) track graft survival and revision but do not separately code the Segond fragment; revision risk is driven by age, graft choice, and rotatory laxity rather than the avulsion itself.

High- vs Limited-Resource Practice

• Well-resourced settings: routine MRI, arthroscopic anatomic ACL reconstruction, selective LET/ALL reconstruction for high-risk knees.
• Limited-resource settings: the plain radiograph alone is a powerful clue - a Segond sign should trigger referral and ACL-focused management even where MRI is delayed or unavailable; structured rehabilitation remains the default first step and may be definitive in low-demand patients.