Segond Fractures

A Segond fracture is a small avulsion fracture of the lateral tibial plateau, the anterolateral ligament (ALL) pulling off its tibial insertion. The fragment is small and non-articular and rarely needs fixation. What matters is what it announces: an ACL tear, with a 75-100% association, and significant rotational instability.

Mechanism. The mechanism is that of the ACL injury, non-contact or contact:

• Non-contact - cutting or pivoting on a planted foot with the knee near extension, and valgus collapse
• Contact - a direct blow causing valgus or hyperextension

Internal rotation combines with the valgus and extension, and force peaks near full extension.

Who. Young athletes: the peak age is 20-30 years, males outnumber females by approximately 2:1, and skiing mechanisms are over-represented. The injury is usually unilateral.

How often. A Segond fracture is seen on the injury radiographs in roughly 7-9% of ACL tears, and in up to about 15% when healed lesions are included (Slagstad et al, AJSM 2020).

The anterolateral ligament. A distinct ligament that runs an oblique course, anterior to the LCL, from the lateral femoral epicondyle to the anterolateral aspect of the lateral tibial plateau, about 5mm below the joint line. Accounts of its femoral origin differ: proximal and posterior to the LCL origin in one, slightly anterior to it in Claes' dissections (see the Evidence Base). It is a secondary stabiliser to internal rotation and works with the ACL to resist rotational instability.

A late re-description. Segond described the fracture in 1879, but the ligament was long thought to be part of the iliotibial band. It was re-described as a discrete structure in 2013 (Claes).

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Why it avulses. Valgus, internal rotation and extension tear the ACL first, since it is the primary restraint. The ALL, weaker than the ACL, then takes excessive internal rotation force and avulses at its insertion on the lateral tibial plateau: the Segond fracture.

Why it matters. Because the ALL and the wider anterolateral complex are secondary restraints to internal tibial rotation, their bony avulsion means the knee has lost its secondary rotational restraint as well as its primary one. The result is a higher-grade pivot shift than an isolated ACL tear. Exactly which structure the fleck comes from is still debated (see Controversies).

The lesion is sorted three ways, and each one points at a decision.

By location. The classic Segond is lateral: an ALL avulsion from the lateral tibial plateau, associated with ACL tear, and the most common type. Location determines which ligament is involved and which cruciate injury to expect.

By ACL association. A Segond fracture with an ACL tear is the most common pattern and is treated by ACL reconstruction. An isolated Segond fracture without ACL tear is rare, less than 5%; it may represent an isolated ALL injury, is usually stable, and is treated conservatively if stable. ACL association determines treatment and prognosis.

By pivot shift grade. A Segond fracture with an ACL tear means more severe rotational instability, a high-grade pivot shift that may benefit from lateral extra-articular tenodesis (LET) alongside the reconstruction. An ACL tear without a Segond fracture carries standard rotational instability and is treated by ACL reconstruction alone.

History. The story is the ACL injury: cutting or pivoting on a planted foot with the knee near extension and valgus collapse, a "pop" or "snap", immediate pain and swelling, and inability to continue the activity. The patient then reports the knee giving way, inability to bear weight, and locking if the meniscus is injured.

Examination. Expect an effusion (haemarthrosis), an antalgic gait and a knee held in slight flexion, with flexion and extension both limited by pain and effusion. Tenderness over the lateral tibial plateau marks the fracture site; joint-line tenderness suggests a meniscal injury and MCL tenderness an MCL injury. The ligament tests:

• Lachman test - positive (anterior translation)
• Anterior drawer - positive (anterior translation)
• Pivot shift - positive (rotational instability), and high-grade with a Segond fracture
• Valgus stress - may be positive if the MCL is injured

Associated injuries. The ACL tear is the most common, and the rest must be looked for on MRI:

• Lateral meniscal tear - 30-40%, posterolateral
• MCL injury - 20-30%
• Bone bruises - posterolateral tibial plateau and lateral femoral condyle (kissing contusion)
• Cartilage injury - lateral femoral condyle (30-40%)

What the test reproduces. The pivot shift reproduces the anterior subluxation, then reduction, of the lateral tibial plateau as the knee moves from extension into flexion. The iliotibial band, converting from an extensor to a flexor at roughly 20-30 degrees, snaps the subluxated plateau back. The IKDC grading is:

• Grade 0: no pivot (equal to the normal contralateral knee)
• Grade I (glide): a smooth, subtle reduction — low-grade
• Grade II (clunk): a distinct jerk or clunk as the plateau reduces — high-grade
• Grade III (gross): a gross clunk with momentary impingement or transient locking of the plateau — high-grade

Why the grade matters. "High-grade" means grade II (clunk) or grade III (gross). The STABILITY randomised trial used a grade 2 pivot shift or greater as one of its enrolment criteria for adding LET, and this is precisely the population a Segond fracture tends to identify.

The acute knee. Guarding and pain make the pivot shift unreliable in the acute, awake knee, so a low-grade or absent pivot shift on the day of injury does not exclude high-grade instability. The examination under anaesthesia at the time of surgery is the definitive grading, and the Segond fragment on the plain film is your early warning of what you will find.

Radiographs. AP and lateral views of the knee. The Segond fracture is a small avulsion from the anterolateral aspect of the lateral tibial plateau, usually 5-10mm and non-articular. The lateral view may show the fragment, but the AP view is diagnostic. Read the same films for a deep lateral femoral notch (below) and, in children, a tibial spine fracture.

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MRI. Always order MRI once a Segond fracture is seen: it is essential for diagnosis and treatment planning. It assesses the ACL (fibre discontinuity, abnormal signal, an empty notch), shows the ALL avulsion itself, maps the kissing-contusion bone bruises of the posterolateral tibial plateau and lateral femoral condyle, and evaluates the meniscus, MCL and cartilage.

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CT. Rarely needed, and usually not required, since MRI is sufficient for diagnosis and treatment planning. Use it to assess fragment size and displacement if fixation is being considered, to evaluate associated fractures and to plan the surgical approach.

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The deep lateral femoral notch sign is the other bony surrogate of ACL rupture you can read off the very same plain radiograph as a Segond fragment. Unlike the Segond fleck, it sits on the femur, not the tibia.

The sign. The lateral femoral condyle normally carries a shallow groove, the condylopatellar sulcus (sulcus terminalis), separating its patellar and tibiofemoral articular surfaces and seen end-on as a small notch on a true lateral radiograph. During the pivot-shift subluxation of an ACL rupture the lateral femoral condyle impacts against the posterolateral tibial plateau, and the osteochondral impaction deepens the sulcus. A depth greater than 1.5mm (some authors use a 2mm threshold) is abnormal, an indirect sign of a torn ACL.

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Why it matters alongside the Segond fragment.

• Two bony clues, one mechanism. Both are skeletal footprints of the same rotatory subluxation event; finding either on plain films should trigger dedicated ACL assessment on MRI.
• The notch localises the bone bruise. The impaction that deepens the notch is the femoral half of the kissing contusion, and a clue to associated lateral meniscal and chondral injury.
• Look on the lateral, not just the AP. The Segond fleck is an AP-view finding and the deep notch is best seen on the true lateral, so a complete plain-film read for suspected ACL injury interrogates both projections.

Specific, not sensitive. The absence of the notch does not exclude an ACL tear. Its presence, like a Segond fracture, is a high-value pointer that saves you from missing the cruciate injury while cross-sectional imaging is awaited.

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.

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The decision. Recognise the fracture on X-ray, order MRI to assess the ACL and associated injuries, then classify the knee as with ACL tear or isolated. The Segond fracture is a marker of severity; the treatment is the treatment of the ligament injury behind it.

With an ACL tear. ACL reconstruction is the primary treatment, indicated by the ACL tear itself, by instability symptoms and in the high-demand patient. It follows standard timing, 4-12 weeks after injury. Consider LET for a high-grade pivot shift (see Surgical Technique).

Isolated. If the knee is stable, with no ACL tear and no instability, treat conservatively with a brace and rehabilitation, and monitor for instability.

Associated injuries. Each is addressed in its own right: meniscal repair if indicated, MCL treatment if needed, and cartilage management.

The fragment. Fixation is rarely indicated. The fragment is small and non-articular, and in most knees it heals or remains asymptomatic without fixation, so most surgeons do not fix it and focus on the ACL reconstruction. The rare indications:

• Large fragment (over 1cm)
• Displaced into the joint
• Symptomatic nonunion
• Surgeon preference, combined with ACL reconstruction

Reading the graft-failure figures. Quote the STABILITY figures rather than a generic range, and note that both are 2-year rates in young high-risk patients aged 25 or under, so they overstate the risk for an older recreational athlete; the 11% is after isolated hamstring ACL reconstruction. The number needed to treat with LET to prevent one graft rupture was 14.3, and composite clinical failure (rupture or residual rotatory laxity) was 40% against 25%, favouring LET.

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The first weeks. The knee sits in a hinged brace locked in extension for 2-4 weeks and is non-weight bearing initially, for 2-3 weeks. Passive ROM begins at 2-4 weeks, when the brace is unlocked.

After reconstruction. The ACL reconstruction does as well as a standard one: a success rate of 85-90%, 80-85% return to pre-injury level, and complications in 10-15% (graft failure, residual pivot shift). Whether the patient returns depends on age, sport level, rehabilitation compliance and LET use.

The fragment. Segond fracture nonunion is quoted at less than 5%, rare and usually asymptomatic, and fixation is rarely needed. Do not confuse that with radiographic healing at reconstruction: in Slagstad's cohort only about a third of fragments had healed between injury and surgery, and a Segond fracture still did not independently raise the risk of revision (Slagstad et al, AJSM 2020). It flags the high-risk phenotype rather than causing failure.

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.

What moves the result. Outcomes are better with an anatomic ACL reconstruction, LET for a high-grade pivot shift, complete rehabilitation and early ROM (2-4 weeks). They are worse with a high-grade pivot shift left without LET, an inadequate reconstruction, incomplete rehabilitation and an early return to sport.

Primary prevention. Proper landing technique (knee flexion, not hyperextension), strength training of the quadriceps and hamstrings, balance and proprioception training, and sport-specific conditioning.

After injury. Complete rehabilitation before return to sport, and continued strength and conditioning. Bracing is controversial and may not prevent reinjury.

Return to sport. Usually at 6-9 months postoperatively, depending on sport and level, and only when the criteria are met:

• Full ROM, equal to the contralateral knee
• Quadriceps strength greater than 90% of the contralateral side
• No effusion
• No instability (negative Lachman and pivot shift)
• Single-leg hop test greater than 90% of the contralateral side
• Agility testing passed and sport-specific drills completed

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.

Related pages: ACL Injuries is the injury a Segond fracture announces - the fragment itself needs nothing, and everything on this page is really about how the ACL is reconstructed; Anterolateral Ligament Injury for the soft-tissue equivalent of this avulsion and the unsettled question of whether that structure is a discrete ligament at all; PCL Injuries and MCL Injuries for the reverse Segond, where a medial tibial rim avulsion should send you looking posteriorly and medially rather than at the ACL; Posterolateral Corner Injuries for the other lateral-sided structures injured by the same varus and rotatory mechanism, and the ones that actually change the operation if missed; Tibial Plateau Fractures and Tibial Spine Fractures for the two periarticular avulsions this must be distinguished from on the injury film; and Paediatric ACL Injury for the skeletally immature knee, in which the tibial spine avulses before the ligament fails.

What exactly avulses? The Segond fragment has been attributed to the anterolateral ligament, the mid-third lateral capsular ligament, the iliotibial band's capsulo-osseous layer, and the anterior arm of the short head of biceps. The ALL re-description (Claes 2013) is the dominant modern view, but the precise soft-tissue origin of the fleck remains debated.

How strong is the ACL association? "Pathognomonic" is the classic teaching, but pooled radiographic series show the lesion in only roughly 7-9% of ACL tears, and rare isolated Segond fractures without ACL rupture exist. The defensible statement is that a Segond fracture is highly specific for, and strongly suggestive of, ACL injury, and should be treated as an ACL tear until proven otherwise - not that the association is universal.

Should the fragment ever be fixed? Most surgeons leave it: it is small and extra-articular, and a Segond fracture does not raise revision risk (see Outcomes). Whether fixing or reconstructing the anterolateral structure adds value beyond standard ACL reconstruction is unsettled.

LET versus ALL reconstruction, and for whom? STABILITY supports adding a lateral procedure in young, high-risk patients, but the optimal technique (modified Lemaire LET versus anatomic ALL reconstruction), the graft and the exact indication thresholds are still being defined. So is whether routine LET over-constrains the lateral compartment in the long term.