The sacrotuberous ligament is a large, flat ligament connecting the posterior pelvis to the ischial tuberosity, forming the medial boundary of the lesser sciatic foramen. It resists the nutation of the sacrum during loading, working with the sacrospinous ligament to prevent sacral rotation forward. Its disruption in high-energy pelvic trauma contributes to posterior ring instability.
| Origin | Posterior inferior iliac spine, posterior sacrum, and coccyx |
|---|---|
| Insertion | Ischial tuberosity |
| Actions | Converts the greater and lesser sciatic notches into foramina; resists sacral nutation; stabilises the posterior pelvis; transmits weight from the sacrum to the ischial tuberosity |
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Bicyclists and rowers develop sacrotuberous ligament tension-related posterior hip pain from the repetitive hip flexion movements that stress the ligament at the posterior sacrum. Hamstring avulsion injuries at the ischial tuberosity are adjacent to the sacrotuberous ligament insertion, making MRI essential to characterise the full extent of posterior hip soft tissue injury in high-energy avulsions.
Sacrotuberous and sacroiliac ligament disruption in vertical shear pelvic fractures producing posterior ring instability requiring surgical stabilisation.
