Martha Lucía Moreno*
* Head nurse, Shaio Hospitalization Clinic.
El Tunal Hospital, Nutritional Therapy Group..com
Pelvic fractures are produced by two mechanisms that determine their severity. When they are produced by a low-energy mechanism, the resulting fracture can be treated conservatively; an example of this is what occurs in the elderly when they fall from their own height.
Fractures caused by high-energy mechanisms such as car crashes, pedestrian collisions, falls from considerable heights, crushing due to collapse or heavy machinery, patients thrown out of moving vehicles, cause loss of continuity of the pelvic ring and are generally accompanied by instability. hemodynamics due to multiple musculoskeletal, visceral, neurological and large vessel injuries that are contained or very close to the pelvic cavity causing local hemorrhage due to the important blood supply to that area, massive retroperitoneal hemorrhage, intra-abdominal hemorrhage, sepsis, producing long-term disabilities; in addition to other injuries to the skull, thorax and abdomen, which worsens the prognosis and increases morbidity and mortality in these patients.
Providing good care to patients with a pelvic ring fracture requires a thorough understanding of the anatomy, type of injury, mechanism of injury, resulting instability, appropriate treatment, and potential complications.
Anatomy of the Pelvic Ring
The pelvic ring is made up of three bones, the iliacus, which is bilateral, formed by: the ilium, ischium and pubis, the third bone is the sacrococcyx that closes the ring from the back, which makes it have intrinsic stability.
The ligaments of the pelvic ring stabilize its joints, offering flexibility and the ability to absorb impacts, which is why a deceleration of 25 km/hour on the lateral side or 45 km/hour on the anteroposterior side is needed to cause fractures. of pelvis.
The anterior sacroiliac ligament and the posterior sacroiliac ligament provide stability to the sacroiliac joint, the posterior sacroiliac ligaments are the strongest in the body and their rupture is a sign of severe high energy injury.
The iliolumbar ligaments connect the iliac crest to the L4 and L5 transverse process.
The pelvic floor is made up of:
• The sacrospinous ligament, which offers resistance to external rotational forces;
• The sacrotuberous ligament, which offers resistance to rotational shear forces.
The sacrospinous and sacrotuberous ligaments connect the sacrum to the ischium.
Within the pelvic cavity there are visceral structures such as: the rectum, urethra, vagina, bladder, prostate and uterus.
The pelvic arteries formed by the bifurcation of the aorta into primitive iliac arteries, which in turn are divided into internal and external iliac arteries.
The following arteries arise from the internal iliac arteries: iliolumbar, superior gluteal, lateral sacral, inferior gluteal, internal pudendal, middle hemorrhoidal and obturator arteries.
From the external iliac the circumflex deep iliac, inferior epigastric, superior hemorrhoidal and superficial external pudendal are detached. The inferior mesenteric and the middle sacral are also found.
Within the pelvis is the origin of the lumbar and sacral nerves that give rise to the plexuses of the same name which provide motor and sensory functions to the lower extremities.
Classification of Pelvic Ring Fractures
There are many classifications, among them are those based on the bone anatomical part involved that help us elucidate its management.
The Tile system classifies the instability that causes the fracture to the pelvic ring and the type of treatment required, without taking into account the mechanism that produced it, grouping all unstable pelvic fractures into the same category, which generally require surgical intervention. and are related to prolonged disabilities.
Type A: Stable
• A1 Fractures that do not affect the pelvic ring; avulsion injuries
• A2 Stable fracture with minimal displacement
• A3 Transverse fractures of the sacrum and coccyx.
Type B: Unstable with rotation; but stable in vertical and posterior direction
• B1 Instability with external rotation; open book injury
• B2 Instability with internal rotation; caused by lateral compression
• B3 Unstable injury with bilateral rotation.
Type C: Unstable with rotation in vertical and posterior directions
• C1 Unilateral injury
• C2 Bilateral injury, one side with rotational instability and the other side with vertical instability
• C3 Bilateral injury, with complete instability on both sides.
Stable fractures may present a very small displacement in the pelvic ring, they are caused by a low-energy mechanism and the fracture occurs in the pubic rami, leaving the posterior part of the ring without any alteration.
Fractures with rotational instability present diastasis in the pubic symphysis accompanied by loss of continuity of the anterior sacroiliac ligament or there may also be injury to the pubic rami and the sacral or sacroiliac joints.
Fractures that present rotational and vertical instability are those that cause a loss of continuity of the posterior and anterior part of the annulus and there is unilateral or bilateral vertical displacement with or without fractures of the acetabulum.
Another classification of fractures is Young’s based on the direction and severity of the forces applied to the pelvis and can be:
Fractures caused by lateral compression: (LC, for its acronym in English) in which the force that causes the injury is directed from the side, both the posterior and anterior parts are affected and the severity depends on the degree of disruption suffered in the posterior part .
• LC I: occurs in elderly patients who suffer falls in which the sacrum is injured without loss of continuity of the ring or injury to the ligaments.
• LC II: when there is a fracture of one wing of the ilium near the sacroiliac joint on the same side of the trauma both posteriorly and anteriorly; It is a stable fracture since there is no disruption of the sacrotuberous and sacrospinous ligaments.
• LC III: fractures produced by a greater force that breaks the contralateral sacrotuberous ligament and the sacrospinous ligaments as well as the posterior axis, leading to rotational and vertical instability on the opposite side of the trauma.
Fractures caused by anteroposterior compression: (APC) are caused by crushing, forces that rotate the legs externally and are transmitted to the pelvis, and forces in the anteroposterior plane occur in a motorcycle accident or pedestrians hit by a vehicle; The severity of the fracture is given by the degree of rupture of the pubic symphysis, the sacrotuberous, sacrospinous, anterior and posterior sacroiliac ligaments, causing in severe cases up to a complete discontinuity of the pelvic ring without bone fracture.
• APC I: a diastasis of the pubic symphysis of less than 2.5 cm occurs due to a lengthening of the posterior ligaments, pelvic stability is preserved, presenting retroperitoneal hematoma and genitourinary lesions.
• APC II: It is an unstable injury resulting from a rotational force. They are also called open book injuries and are the result of rupture of the sacrotuberous, sacrospinous, anterior sacroiliac ligaments and the pubic symphysis.
• APC III: They are fractures that cause rotational and vertical instability, accompanied by a high mortality rate since they are associated with significant retroperitoneal bleeding and occur due to the rupture of the anterior and posterior sacroiliac ligaments.
Fractures caused by vertical section: (VS) are the result of longitudinal forces that can be indirect in one leg and that are transmitted to the ipsilateral hemipelvis, as occurs in falls from great heights causing rotational and vertical instability.
Fractures caused by a combination of previous mechanisms: (CM) fractures associated with complex trauma usually accompanied by shock and sepsis.