Pelvic Ring Injuries — ATLS & Tile

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

• 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

• 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