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The Segond fracture is now understood to result from avulsion of structures within the anterolateral complex, notably the anterolateral ligament (ALL) and lateral capsule.
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A radiographic marker of injury to the anterolateral ligament complex," including the ALL, lateral capsule, and sometimes ITB.
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Anterolateral ligament (ALL)
| Feature | Description |
|---|---|
| Origin | Lateral femoral epicondyle, anterior and slightly distal to LCL origin |
| Insertion | Proximal anterolateral tibia, midway between Gerdy's tubercle and fibular head, just distal to the lateral tibial plateau |
| Function | Resists internal tibial rotation, especially at 30–90° flexion |
| MRI | Best seen on coronal oblique PD-weighted images, running anteroinferior to the lateral tibial plateau. Edema or discontinuity at the insertion suggests ALL injury. |
Other Key Structures in the anterolateral complex (ALC)
| Structure | Imaging Notes |
|---|---|
| ‣ | Inserts on Gerdy’s tubercle; can transmit rotational forces contributing to Segond avulsion |
| Lateral capsule | Blends with the ALL and ITB; capsular avulsion may accompany Segond fracture |
| Lateral meniscus anterior horn | Lies close to the ALL insertion; may also be involved in complex injuries |
According to Helito et al., the
Distinctive features:
| Feature | Description |
|---|---|
| Location | Just below the lateral tibial plateau rim |
| Shape | Curvilinear or crescent-shaped avulsion fragment |
| Size | 5–15 mm usually |
| Significance | Correlates with ACL rupture, seen in up to 75–100% of cases; reflects internal rotation injury pattern |
28-year-old man with Segond fracture after motorcycle crash: A, In coronal PDFS-W image, meniscotibial component of anterolateral ligament (ALL) can be seen attaching to Segond fracture fragment. ITB = iliotibial band. B, Corresponding frontal radiograph shows nearly imperceptible displaced fracture fragment (arrow) adjacent to lateral tibial plateau
Porrino J, Maloney E, Richardson M, Mulcahy H, Ha A, Chew FS. The Anterolateral Ligament of the Knee: MRI Appearance, Association With the Segond Fracture, and Historical Perspective. American Journal of Roentgenology. 2015;204(2):367-373. doi:https://doi.org/10.2214/ajr.14.12693
MRI Identification of ALL & Segond Fragment:
| Sequence | Findings |
|---|---|
| PD-weighted coronal oblique | Hypointense band (ALL) from lateral femoral epicondyle to proximal tibia; look for discontinuity, edema |
| T2 FS sagittal/coronal | Segond fragment seen as low-signal bone fragment near lateral tibial rim; surrounding marrow edema in tibia |
| Axial T2 | Useful for identifying ITB, Gerdy’s tubercle, and associated contusions |