Characteristics

• Usually secondary to massive force such as a road-traffic accident or fall from a height.

• May be associated with vascular, soft-tissue and visceral injuries.

• If the ring is broken in two places the fracture is likely to be unstable – don't forget the sacroiliac joint as a site of disruption.

• Isolated ring fractures tend to be stable, e.g. an isolated pubic ramus fracture.

Tile classification –

• A – stable – Not involving the pelvic ring (e.g. avulsion fractures) or minimally displaced involving the pelvic ring (pubic rami fractures).

• B – vertically stable, rotationally unstable – AP compression (open book) and lateral compression (e.g. rami fracture with associated crushing injury of the sacroiliac joint).

• C – unstable – Disruption of the pelvic ring at two or more levels (e.g. bilateral rami fractures or pubic symphysis disruption).

Clinical features

• Suspect from history.

• Haemorrhagic shock is commonly seen due to vascular nature of the pelvic bones, closely related large vessels and large associated muscle groups.

• Shock is often compounded by haemorrhage from associated injuries in the thorax, abdomen and extremities.

• Beware urogenital and rectal disruption – look for perineal bruising, high or impalpable prostate and blood at the urethral meatus.

• Gentle pelvic testing may reveal instability. Avoid repeated examination.

• In the elderly, they may present similarly to suspected femoral neck fracture.

Radiological features

• Obtain pelvic views in multiple trauma patients and with unexplained shock following trauma.

• Assess the pelvic ‘rings’ for steps or asymmetry.

• Compare like for like, bearing in mind rotational differences.

• Always closely examine the pubic rami and acetabulae in the elderly patient with a suspected neck-of-femur fracture.

• CT is a very useful modality to assess severity, reveal associated injuries and assist in the planning of surgery.