Pelvic & Acetabular Trauma MCQs

In a hemodynamically unstable patient with a pelvic ring injury despite binder application and adequate resuscitation (and a negative FAST exam), preperitoneal pelvic packing or pelvic angiography with embolization is indicated. Packing directly addresses the most common source of bleeding (venous plexus). A C-clamp is contraindicated in APC injuries.

A pelvic binder should be centered over the greater trochanters to effectively close the pelvic ring volume in "open book" (APC-type) injuries. Placing the binder over the iliac crests is ineffective and can paradoxically widen the pelvis or compromise abdominal assessment.

An anteroposterior compression (APC) II injury involves symphyseal diastasis >2.5 cm with tearing of the sacrotuberous, sacrospinous, and anterior sacroiliac ligaments. The posterior sacroiliac ligaments remain intact, leading to a rotationally unstable but vertically stable pelvis. APC III involves complete disruption of both anterior and posterior SI ligaments.

APC-III injuries involve complete disruption of the anterior and posterior sacroiliac ligaments, leading to a completely unstable hemipelvis. This mechanism typically results in the highest volume of retroperitoneal hemorrhage and has the highest mortality and transfusion requirement among pelvic ring injuries.

An APC III injury implies a complete anterior and posterior disruption of the hemipelvis. This includes the symphysis pubis anteriorly, and the anterior SI, posterior SI, sacrotuberous, and sacrospinous ligaments posteriorly, resulting in a completely unstable hemipelvis.

A pelvic circumferential compression device (binder or sheet) must be placed at the level of the greater trochanters to effectively close the pelvic ring and reduce pelvic volume. Placement over the iliac crests is incorrect and can act as a fulcrum to worsen pelvic displacement.

Pelvic binders are most effective at reducing pelvic volume and controlling hemorrhage when placed accurately at the level of the greater trochanters. Placement higher over the iliac crests can paradoxically worsen the deformity.

An APC-II injury is characterized by a widened symphysis pubis and disruption of the anterior sacroiliac (SI), sacrotuberous, and sacrospinous ligaments, but the critical posterior SI ligaments remain intact, providing rotational instability but vertical stability. An APC-III injury involves the complete disruption of both the anterior and posterior SI ligaments, resulting in both rotational and vertical instability.

An APC II injury is characterized by symphyseal diastasis >2.5 cm and disruption of the anterior sacroiliac ligaments, sacrospinous, and sacrotuberous ligaments, while the posterior SI ligaments remain intact. This causes rotational instability but maintains vertical stability.

In the Young-Burgess classification, an APC I injury involves only symphyseal widening (< 2.5 cm). APC II involves rupture of the symphysis, anterior sacroiliac ligaments, sacrotuberous, and sacrospinous ligaments, but the posterior sacroiliac ligaments remain intact (opening book). APC III implies a complete disruption, including the robust posterior sacroiliac ligaments, leading to full hemipelvis instability.

To achieve optimal closure of an open book pelvic fracture (which reduces pelvic volume and helps tamponade venous and cancellous bone hemorrhage), the compressive force must be applied appropriately through the hip joints. A pelvic binder or tightly wrapped sheet should be centered directly over the greater trochanters. Placing the binder too high (over the iliac crests or abdomen) is biomechanically ineffective and can paradoxically worsen the deformity by pushing the iliac wings inward while the pubic symphysis remains splayed open.

An APC II injury involves an external rotation force that opens the anterior pelvic ring (symphysis diastasis). In the posterior ring, it specifically tears the anterior sacroiliac ligament, the sacrotuberous ligament, and the sacrospinous ligament. The robust posterior sacroiliac ligaments remain completely intact, acting as a hinge. This creates rotational instability but preserves vertical stability. Disruption of both anterior and posterior SI ligaments would constitute an APC III injury.

The optimal placement for a pelvic binder is centered directly over the greater trochanters. Placing it higher (over the iliac crests or ASIS) is a common error that can fail to reduce the pelvic volume effectively and may even paradoxically open the pelvic ring in some fracture patterns.

An APC III injury implies complete disruption of the pubic symphysis anteriorly, as well as rupture of both the anterior AND posterior sacroiliac ligaments posteriorly, resulting in complete rotational and vertical instability of the hemipelvis.

An APC III injury involves a severe anteroposterior force that causes symphyseal diastasis and complete disruption of the anterior sacroiliac, sacrotuberous, sacrospinous, AND posterior sacroiliac ligaments, leading to complete global (rotational and vertical) instability of the hemipelvis. APC II involves anterior SI, sacrotuberous, and sacrospinous disruption, but the posterior SI ligaments remain intact (rotationally unstable, vertically stable).

The corona mortis is a vascular anastomosis between the external iliac (or inferior epigastric) and obturator vessels. It is located on the posterior aspect of the superior pubic ramus and is at high risk during anterior pelvic exposures.

Pelvic binders should be placed at the level of the greater trochanters to effectively close the pelvic ring and reduce pelvic volume. Placement over the iliac crests is less effective and may inadvertently cause paradoxical widening of the true pelvis.

In an APC III pelvic fracture, especially with hemodynamic instability, the pelvic ring is often widely disrupted, leading to significant volume loss within the pelvic cavity due to venous and arterial bleeding. While transfusion is critical, and angiography may be needed, the most critical immediate orthopedic intervention after initial resuscitation is mechanical stabilization of the pelvic ring using a C-clamp or external fixator. This reduces the pelvic volume, tamponades bleeding, and reduces ongoing hemorrhage. Angiography is typically performed after mechanical stabilization if the patient remains hemodynamically unstable, indicating persistent arterial bleeding. ORIF and traction are definitive treatment steps, not immediate life-saving measures.

An APC II pelvic injury is characterized by pubic symphysis diastasis and tearing of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments. The strong posterior sacroiliac ligaments remain intact, rendering the pelvis rotationally unstable but vertically stable.

In the Young-Burgess classification, APC injuries involve varying degrees of diastasis of the symphysis pubis. APC II involves disruption of the symphysis, sacrotuberous, sacrospinous, and anterior sacroiliac ligaments, but the posterior sacroiliac ligaments remain intact (opening book injury). An APC III injury is characterized by the additional complete disruption of the posterior sacroiliac ligaments, resulting in complete hemipelvic instability (both rotational and vertical).