Introduction

Avulsion fracture of the ischial tuberosity is a rare injury in comparison with mid-substance tears of the hamstrings, and its diagnosis is often missed. Such fracture usually occurs between puberty and late adolescence in those who do a lot of sport—it is in puberty that the secondary ossification centre or apophysis appears and in late adolescence that it fuses. In other words, fracture occurs at a time when the apophysis is the weakest link in the chain of muscle, tendon, and bone. The cause is usually forcible contraction of the hamstrings, as in sports such as sprinting and hurdling.

In adolescent patients with a history of proximal hamstring injury and current ischial tenderness, a radiograph of the pelvis should be performed. This is to exclude the presence of an avulsion fracture, which may be substantially displaced.

A prompt diagnosis of a displaced avulsion fracture of the ischial tuberosity will enable early surgery where appropriate. This in turn will prevent the development of chronic pain on sitting and walking and an inability to return to sporting activities.

Case reports