Fibular Styloid Process

processus styloideus fibulae

The fibular styloid (fibular apex) is the pointed posterolateral projection at the tip of the fibular head, providing the principal attachment of the lateral collateral ligament, the popliteofibular ligament, the biceps femoris long and short heads, and the arcuate ligament. It is the posterolateral corner (PLC) bony anchor on the fibula and represents the convergence of all the major lateral knee stabilisers onto the fibular head.

Region: Knee

Clinical Relevance

Clinical Notes

The fibular styloid is the key anatomical attachment point for all posterolateral corner structures, and its avulsion fracture (arcuate fracture or lateral capsular sign) is a pathognomonic radiographic finding of PLC injury in knee trauma. The small bony fragment avulsed from the fibular styloid by the lateral capsule and arcuate ligament in varus injury appears as a small fleck of bone at the fibular head on AP radiograph (the Arcuate sign). PLC reconstruction targets the fibular styloid as the primary fibular fixation point for graft placement.

Pathology

Common Injuries & Conditions

Fibular Styloid Avulsion — The Arcuate Sign

High-energy varus and external rotation knee injury avulses the fibular styloid with the attached LCL, popliteofibular, and arcuate ligaments, producing the arcuate sign on AP radiograph — a small fleck of bone at the lateral fibular head indicating PLC injury requiring surgical reconstruction of all avulsed structures.