Executive Editor: Peter Trafton

Authors: Rahul Banerjee, Peter Brink, Matej Cimerman, Tim Pohlemann, Matevz Tomazevic

Pelvic ring - Intact posterior arch, innominate bone avulsion fracture

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1 Introduction top


These fractures are most common in young active people. They do not compromise the stability of the pelvic ring and are mainly treated conservatively with guided physiotherapy.

Indication for operative treatment is displacement larger than 1 – 2 cm, especially in young active athletes.

The most common avulsion fractures involve the anterior and inferior iliac spine. More rarely the symphysis and ischial tuberosity. The dislocation of the avulsed fragment always follows the direction of muscle contraction.

All these avulsions are treated in a similar fashion.

2 Patient preparation top


Patient preparation

This procedure is performed with the patient either in a supine or a prone position.

3 Reduction top


Preparation of fracture site

The avulsed apophysis is exposed through an overlying incision. Typically, the anterior portion of an anterior iliac approach is used for anterior superior or inferior iliac spines. For an ischeal apophyseal avulsion, the patient is placed prone. A transverse sub-gluteal incision (along the gluteal crease) can be used to approach the site from its medial side. The sciatic nerve and posterior femoral cutaneous nerve are lateral and deeper than the tuberosity, and can be avoided or exposed if necessary.

The avulsion fracture is exposed with sharp and blunt dissection. Its muscle attachments are preserved. Displacement is increased if necessary with a lamina spreader or retractor, so the fracture surfaces can be cleaned of debris, interposed periosteum, and ligaments.



Reduction is performed using a small pointed reduction forceps together with a K-wire as a joystick.


Temporary fixation is achieved by further insertion of the K-wire.

4 Fixation top


Preparation of fracture site

The fragment is fixed by insertion of a 3.5 mm half threaded cancellous screw inserted as a lag screw. A plastic pointed washer is used.

The screw should be inserted through the muscle attachment perpendicular to the fracture line.


In larger fragments (such as the ischial tuberosity), additional screws may be inserted.



After completion of internal fixation, confirm the final reduction and hardware position intraoperatively by AP, inlet and outlet radiographic imaging.

v1.0 2015-12-10