The TFL is a small muscle at the anterior iliac crest that inserts entirely into the iliotibial band rather than bone, making it a hip flexor-abductor and an ITB tensioner simultaneously. It is often overactive in runners with weak hip abductors, contributing to ITB syndrome and lateral knee pain through excessive ITB tension.
| Origin | Anterior superior iliac spine and anterior iliac crest |
|---|---|
| Insertion | Iliotibial band — inserts via the ITB on Gerdy's tubercle of the lateral tibial condyle |
| Nerve Supply | Superior gluteal nerve (L4, L5) |
| Blood Supply | Superior gluteal and lateral circumflex femoral arteries |
| Actions | Hip flexion; Hip internal rotation; Hip abduction; Tenses the iliotibial band to stabilise the knee in extension |
|---|
The TFL and gluteus maximus both insert into the ITB, converting it into a structural cable that transmits lateral hip forces to the lateral knee and tibia. TFL overactivity relative to the posterior hip muscles produces the excessive anterior ITB tension that generates lateral knee friction in running.
TFL tightness is assessed by the Thomas test and modified Ober test. In ITB syndrome, TFL foam rolling and hip strengthening (particularly hip abductors and external rotators) reduce TFL overactivity. AIIS avulsion fractures in adolescents involve the TFL origin alongside the rectus femoris direct head.
The TFL is palpable as the anterolateral hip muscle just distal to the ASIS, becoming firm during resisted hip abduction and internal rotation.
Excessive TFL tension on the iliotibial band producing lateral knee friction pain in runners managed with hip strengthening and TFL flexibility work.
