Overview & Epidemiology
Pelvic ring injuries represent some of the most complex and potentially lethal injuries in trauma orthopaedics. The pelvis is a rigid ring structure and fractures that disrupt this ring — especially posteriorly — are mechanically unstable and can cause massive retroperitoneal haemorrhage. The mortality from open-book pelvic fractures with haemodynamic instability approaches 40–50% without prompt, systematic management. The ATLS (Advanced Trauma Life Support) protocol provides the emergency management framework, while the Tile (AO/OTA) classification guides definitive surgical planning by categorising fractures according to their mechanical stability.
- Anatomy of the pelvic ring: the pelvic ring is formed by the two innominate bones (ilium, ischium, pubis) and the sacrum; it is maintained by a series of ligamentous structures that resist specific deforming forces: the anterior elements (symphysis pubis — resists diastasis/external rotation; pubic rami — bony ring anteriorly); the posterior elements are the most important stability determinants — the posterior sacroiliac ligaments (posterior and interosseous SI ligaments — the strongest ligaments in the body) resist vertical shear; the sacrospinous and sacrotuberous ligaments resist external rotation and vertical shear respectively; the floor is provided by the pelvic floor muscles
- Haemorrhage sources: the most immediately life-threatening complication of pelvic ring disruption; the pelvis is a vast retroperitoneal space that can accommodate 4–5 litres of blood without any external evidence; sources of haemorrhage: (1) Venous — presacral venous plexus (most common — ~85% of pelvic haemorrhage); the venous plexus around the sacrum and SI joint is disrupted; venous bleeding typically tamponades when the pelvic volume is reduced with a binder; (2) Arterial — the superior gluteal artery (most commonly injured arterial vessel — the internal iliac/hypogastric artery branches are torn); arterial bleeding does NOT respond to pelvic binder and requires angiographic embolisation; fractures with ongoing haemorrhage despite binder = suspect arterial bleeding
Tile (AO/OTA) Classification
| Tile Type | Injury Pattern | Mechanism | Stability | Haemorrhage Risk |
|---|---|---|---|---|
| Type A — Stable | The posterior arch is INTACT; the pelvic ring is stable; includes: avulsion fractures (ASIS — sartorius; AIIS — rectus femoris; ischial tuberosity — hamstrings; iliac wing fractures — Duverney fracture); undisplaced pubic rami fractures; transverse sacral fractures below S2; isolated pubic symphysis diastasis <2.5 cm | Avulsion (muscular pull — athletes); direct lateral compression; low-energy falls in elderly | Stable — posterior SI ligaments intact; the ring is intact posteriorly | Low (posterior ring intact; haematoma limited) |
| Type B — Rotationally unstable, vertically stable | Partial disruption of the posterior arch; the posterior SI ligaments (the primary vertical stability structures) remain INTACT; but there is rotational instability; sub-types: B1 (Open book — APC II/III): anterior compression opens the pelvic ring like a book (external rotation); symphysis diastasis >2.5 cm; the anterior SI ligaments and sacrospinous/sacrotuberous ligaments are torn but the posterior SI ligaments remain intact; B2 (Lateral compression — ipsilateral): internal rotation force on one hemipelvis, impacting the sacral ala; the hemipelvis internally rotates (closes the book); ipsilateral rami fractures with sacral compression; B3 (Lateral compression — contralateral / bucket handle): internal rotation on one side + external rotation on the other | B1: anterior AP compression (steering wheel, front-on impact); B2: lateral impact (side impact — most common pelvic fracture pattern in road traffic accidents) | Rotationally unstable (the hemipelvis can rotate in/out); vertically stable (posterior SI ligaments intact prevent vertical translation) | Moderate (B1 open book carries highest haemorrhage risk of Type B — the pelvic volume is dramatically increased by the external rotation; pelvic binder reduces volume and tamponades venous bleeding) |
| Type C — Rotationally AND vertically unstable | Complete disruption of the posterior arch — BOTH the anterior AND posterior SI ligaments are torn; the hemipelvis is completely unstable in all planes; includes complete SI joint dislocation, sacral fractures through the neural foramina (Denis Zone II/III), and iliac wing fractures with posterior extension; C1 (unilateral); C2 (bilateral — bilateral complete instability); C3 (bilateral + acetabular fracture); the entire posterior tension band is disrupted | Vertical shear mechanism (fall from height — the hemipelvis is driven superiorly by axial load through the lower extremity); combined AP + vertical shear in high-energy trauma | Both rotationally AND vertically unstable; the hemipelvis can translate superiorly (vertical shear — `VS` pattern); limb length discrepancy; perineal lacerations; L5 nerve root/sacral plexus injury from posterior displacement | Very high — massive retroperitoneal haemorrhage; the completely unstable pelvis has no self-tamponade mechanism; both venous and arterial injury; mortality 30–50% in haemodynamically unstable Type C fractures |
Young-Burgess Classification (Mechanism-Based)
| Pattern | Sub-type | Injury Description | Haemorrhage Risk |
|---|---|---|---|
| APC (Anteroposterior Compression) | APC I | Symphysis diastasis <2.5 cm; anterior SI stretched but intact; sacrospinous/sacrotuberous intact | Low |
| APC II | Symphysis diastasis >2.5 cm; anterior SI ligaments torn; sacrospinous/sacrotuberous torn; posterior SI ligaments INTACT; `open book` — rotationally unstable, vertically stable; Tile B1 | Moderate-high; pelvic binder reduces volume and tamponades | |
| APC III | Complete disruption of all SI ligaments (anterior + posterior); complete SI joint disruption; rotationally AND vertically unstable; Tile C1 | Very high; associated with highest haemorrhage rates of all pelvic fracture patterns | |
| LC (Lateral Compression) | LC I | Posterior sacral compression fracture + ipsilateral horizontal pubic rami fractures; the hemipelvis internally rotates; `closed book` | Low (volume is reduced — tamponades) |
| LC II | Crescent fracture of the ilium (posterior ilium fracture through the SI joint region) + ipsilateral rami; the posterior SI region is disrupted; rotationally unstable | Moderate | |
| LC III | `Windswept pelvis` — ipsilateral LC + contralateral APC (bucket handle); bilateral injury; one hemipelvis internally rotated, one externally rotated | High — combined pattern with bilateral disruption | |
| VS (Vertical Shear) | Complete posterior arch disruption with superior migration of the hemipelvis; all ligaments torn; Tile C; highest injury severity | Very high — highest mortality of all pelvic patterns | |
ATLS Management
- Pelvic binder: the single most important immediate intervention for an open-book pelvic fracture (APC II/III) with haemodynamic instability; a circumferential pelvic binder (SAM Pelvic Sling, T-POD) is applied at the level of the greater trochanters (NOT the iliac crests — too high and ineffective); the binder compresses the pelvis, reduces the pelvic volume, and tamponades the venous plexus haemorrhage; dramatically reduces blood loss in open-book fractures; apply in the ED at the time of primary survey; check that the binder is correctly positioned (trochanter level) on the trauma X-ray
- Damage control resuscitation: massive transfusion protocol (1:1:1 PRBCs:FFP:platelets); permissive hypotension (systolic 80–90 mmHg until haemorrhage controlled); tranexamic acid within 3 hours (CRASH-2); avoid crystalloid over-resuscitation (dilutes clotting factors, worsens coagulopathy)
- Haemostasis options when binder + resuscitation fails (persistent haemodynamic instability): (1) Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) — inflatable balloon catheter placed in the aorta (Zone III — infrarenal aorta) via a femoral artery approach; occludes aortic flow distal to the balloon; dramatically reduces pelvic blood flow; bridges the patient to definitive haemostasis; (2) Retroperitoneal packing (preperitoneal pelvic packing — PPP): a midline infraumbilical incision accesses the preperitoneal space; large surgical swabs are packed bilaterally around the SI joints and presacral plexus; tamponades venous bleeding directly; most effective for venous haemorrhage; swabs removed at 24–48 hours; (3) Angiographic embolisation: interventional radiology with selective embolisation of bleeding arterial vessels (superior gluteal, internal pudendal, obturator); for arterial haemorrhage; requires haemodynamic stability to transfer to the angio suite; less effective for venous bleeding; complementary to packing, not a replacement
- Definitive fixation: anterior ring — symphyseal plating (for diastasis >2.5 cm); pubic rami — INFIX (subcutaneous anterior pelvic fixator using SI screws and a subcutaneous rod) or percutaneous rami screws; posterior ring — SI joint screws (for SI dislocation); sacral fractures — SI screws or sacral bar; complex unstable fractures — combined anterior + posterior fixation; definitive fixation typically at day 3–10 after physiological stabilisation
Exam Pearls
- Tile classification: A (stable — posterior arch intact); B (rotationally unstable, vertically stable — posterior SI ligaments intact); C (rotationally + vertically unstable — all posterior ligaments torn); Type C = vertical shear = highest mortality
- B1 open book (APC II): symphysis >2.5 cm; anterior SI + sacrospinous/sacrotuberous torn; posterior SI intact; pelvic volume increased; pelvic binder reduces volume and tamponades venous haemorrhage
- Pelvic binder position: greater trochanter level (NOT iliac crests); compresses the pelvic ring; most effective for APC II/III open book injuries; less effective for LC and VS fractures (ring already closed or complex); apply in ED during primary survey
- Haemorrhage sources: venous (presacral plexus — 85%, responds to binder/packing); arterial (superior gluteal artery most common — 15%, requires angioembolisation); persistent instability despite binder = likely arterial → angiography
- REBOA (Zone III — infrarenal aorta): bridges the patient to definitive haemostasis; reduces pelvic arterial flow; increasingly used in major trauma centres; inserted via femoral artery; complements preperitoneal packing for combined arteriovenous haemorrhage
- Preperitoneal pelvic packing (PPP): most effective for venous presacral haemorrhage; pack bilateral paravesical spaces; 24–48 hour pack removal; complements angioembolisation for arterial component
- Young-Burgess: APC (open book — external rotation — increases volume); LC (lateral compression — internal rotation — closes book); VS (vertical shear — all ligaments torn — vertical migration of hemipelvis); APC III = highest haemorrhage; VS = highest mortality
- Denis sacral fracture zones: Zone I (lateral ala — L5 nerve root; 5.9% neurological deficit); Zone II (through foramina — L5/S1/S2; 28.4% neurological deficit); Zone III (central canal — cauda equina; 56.7% neurological deficit — highest risk; bladder/bowel dysfunction)
- SI screw fixation: standard for posterior ring stabilisation (SI dislocation, sacral fractures); placed percutaneously under fluoroscopic guidance into the S1 or S2 sacral body; risk of L5 nerve root injury if screw placed too anterosuperior; `corridor` must be confirmed on inlet, outlet, and lateral fluoroscopic views