Gerdy Tubercle

tuberculum tractus iliotibialis

Gerdy tubercle is a bony prominence on the anterolateral surface of the proximal tibia, approximately 1 cm lateral and distal to the lateral tibial plateau. It is the primary bony insertion of the iliotibial band and is a consistent palpable landmark on the lateral knee. The tubercle is oriented slightly anteriorly so that the IT band exerts both a distal and slightly posterior pull at full extension.

Region: Knee

Clinical Relevance

Clinical Notes

Gerdy tubercle is the attachment point avulsed in Segond fractures, a small flake avulsion from the anterolateral tibia pathognomonic of ACL rupture and anterolateral ligament injury. On plain radiograph, a small lateral tibial rim fragment at Gerdy tubercle level should prompt MRI assessment for ACL and anterolateral complex injuries. The tubercle is also the distal endpoint for IT band friction assessment and is the palpation target in testing IT band syndrome at the lateral knee.

Pathology

Common Injuries & Conditions

Segond Fracture

An avulsion of the anterolateral tibial rim at or near Gerdy tubercle by the anterolateral ligament and IT band during internal rotation and varus stress, pathognomonic for ACL rupture on X-ray, requiring MRI to characterise the full ligamentous injury pattern.

IT Band Insertion Tendinopathy

Repetitive friction of the IT band across the lateral femoral epicondyle and at its Gerdy tubercle insertion produces lateral knee pain in runners, managed with activity modification, hip abductor strengthening, and stretching.