What are Segond fractures of the knee and their mechanism?

From the Guidelines

A Segond fracture is a small avulsion fracture of the lateral tibial plateau of the knee, typically involving the middle third of the lateral tibial condyle, and is highly associated with anterior cruciate ligament (ACL) tears. The mechanism of a Segond fracture involves the anterolateral ligament or the iliotibial band pulling a small fragment of bone from the lateral tibial plateau during a pivoting injury, which occurs when a force causes internal rotation of the tibia while the knee is in slight flexion, combined with varus stress 1. Key characteristics of Segond fractures include:

• Typically involving the middle third of the lateral tibial condyle
• Highly associated with ACL tears, with approximately 75-100% of patients with Segond fractures also having ACL injuries
• Patients typically present with knee pain, swelling, and instability following a twisting injury
• On physical examination, there may be lateral joint line tenderness and a positive anterior drawer test or Lachman test due to the associated ACL tear
• Diagnosis is confirmed with knee radiographs showing the characteristic small bone fragment lateral to the tibial plateau, though MRI is often needed to evaluate the associated soft tissue injuries
• Treatment generally focuses on addressing the associated ligamentous injuries, particularly ACL reconstruction, rather than the Segond fracture itself, which typically heals without specific intervention A recent study by Klos et al, as referenced in 1, showed a higher prevalence of Segond avulsions fractures on US studies than previously reported in literature on the MRI or radiography, highlighting the importance of thorough evaluation for concomitant knee injuries in patients with Segond fractures. The presence of a Segond fracture should always prompt a thorough evaluation for concomitant knee injuries, including ACL tears and other ligamentous injuries, to ensure proper treatment and management of the condition.

From the Research

Definition and Mechanism of Segond Fractures

• A Segond fracture is an avulsion fracture of the lateral tibial plateau, widely considered to be pathognomonic of anterior cruciate ligament (ACL) rupture 2.
• The fracture is associated with a ligament recently termed the anterolateral ligament, and is located on the anterolateral aspect of the tibia 3.
• The mechanism of injury is often a non-contact mechanism, with sports injuries being the most common cause, and is associated with a higher grade pivot shift 2, 3.

Incidence and Association with ACL Rupture

• The incidence of Segond fractures associated with ACL rupture is reported to be around 2.4% to 7.4% in different studies 2, 4, 5.
• Segond fractures are associated with significant intra-articular pathology, such as meniscal injuries, as well as extra-articular pathology, such as collateral ligament injuries 2.
• The presence of a Segond fracture may represent increased rotatory instability, and is associated with a higher risk of concomitant isolated lateral meniscus tear in ACL ruptures 2.

Treatment and Prognosis

• Direct repair of the Segond fracture and plication of the anterolateral capsule in patients with an ACL rupture and a high-grade pivot shift demonstrate good clinical outcomes, restoration of rotational stability, and maintenance of knee range of motion at 2 years postoperatively, with no major complications 3.
• The presence of a Segond fracture does not appear to predispose to early ACL graft failure, and can be ignored at the time of primary ACL reconstruction 4, 5.
• The spontaneous healing rate of Segond fractures is reported to be around 35.6% to 90% in different studies 4, 5.