Pelvic Fractures occur more commonly in males who are likely to become injured in high impact crashes. Fractures of the pelvis can happen in the elderly with a simple fall from a standing height. The incidence of pelvic fractures is about 37 cases per 100,000 people in the US per year.
The pelvic ring is formed from the sacrum and two innominate bones that are connected in the front by the symphysis pubis and by the sacroiliac joints in the back. The innominate bone is essentially three bones that have become fused together: 1) the ilium; 2) the ischium; and 3) the pubis. The pelvis is inherently stable because of ligaments that keep the pelvis connected in several different places.
A stable pelvic bone fracture is one that stays in the right place even after applying normal physiological forces to the bone. An unstable injury is displaced and can be unstable in rotation or in vertical movements.
Mechanism of Injury
There are both low energy mechanisms and high-energy mechanisms. The high-energy mechanisms result in fractures that disrupt the pelvic ring. Low energy mechanisms can occur in sports and can result in an avulsion fracture of the pelvis. Crush injuries can occur as part of motor vehicle trauma and can result from the patient being crushed beneath a motor vehicle on the ground or being rolled over by something.
A common motorcycle crash injury results in disruption of the symphysis pubis so that the pelvis springs open, held together only by the posterior ligaments. A lateral compression injury can come out of being T-boned by another vehicle so that lateral forces are applied to the pelvis. This can cause various injuries to the pelvis, including fracture of the ilium or the iliac ring. There can also be a fracture of the acetabulum when direct trauma strikes the hips.
Evaluation of Pelvic Fractures
These fractures rarely occur in isolation so that a full trauma evaluation must be undertaken. This includes management of airway, breathing, and circulation before addressing the bony injuries. There can be serious hemorrhaging as a result of a pelvic fracture so that circulation can be compromised. There can be disruption of the venous plexus in the back part of the pelvis or disruption of the iliac vessels.
These need emergency surgery to correct the bleeding so the patient doesn’t die of hemorrhage. MAST trousers can be used to stabilize the pelvic fracture and reduce the amount of bleeding. A pelvic binder can be placed around the pelvis in order to stabilize it.
There can be injury to the lumbosacral plexus and nerve roots during a pelvic fracture. Gastrointestinal and urinary tract injuries are common, with bladder injuries occurring in 20 percent of pelvic fractures. Urethral injury occurs primarily in male patients where it can affect up to 10 percent of urethras involved in pelvic fractures. Perforations of the bowel or rectum can occur, making the fracture an open fracture.
X-rays should be done of the AP and lateral views of the pelvis along with lateral views of the cervical spine and chest x-ray because of other trauma. X-rays can show fractures of the pubic rami and displacement of the symphysis pubis. There are special views of the pelvis that can specifically identify acetabular fractures and sacroiliac dislocations. CT scan of the pelvis may be necessary to further identify fractures and dislocations of the pelvic bones. MRI is less helpful because it takes extra time that a critically ill patient cannot afford to waste. Views by pushing or pulling on the pelvis can be done when the patient is under general anesthesia. These views assess the pelvis for vertical instability.
If the sacroiliac joint is displaced by 5 mm or if there is a posterior fracture gap, the pelvis is considered unstable. It is also considered unstable if there is an avulsion fracture of the L5 transverse process, the lateral border of the sacrum or injury to the ischial spine.
Treatment of Pelvic Fractures
Pelvic fractures are difficult to treat and the treatment varies from doctor to doctor. Some fractures can be managed without surgery if they are stable. The patient needs to get around using a walker or crutches and the bones will knit together because the ligaments are holding the bony fragments in place.
If the fracture is open, or if there is perforation of the bowel, then surgery is indicated. If there is loss of mechanical stability because the symphysis pubis has separated, then surgery might be necessary. The same is true if there is a leg length discrepancy, rotational deformity, intractable pain, or sacral displacement more than 1 centimeter.
External fixation can be done using pins spaced apart along the anterior iliac crest. This is just a temporary measure in order to stabilize the patient. Plates can be used to hold the pubic symphysis together and bars might be used to fix the sacroiliac joint together.
Priority must be given to the GI tract and genitourinary system as these can indicate open fractures and surgical repair of non-orthopedic injuries. The vagina must be assessed in women and the rectum must be evaluated in both men and women to see if there is disruption of tissue. Colostomy might be necessary in cases of bowel perforation or injuries to the rectal/anal areas. Bladder ruptures need to be repaired as part of healing from a pelvic injury. Neurological injuries are possible, depending on where the fracture(s) are located. Care must be taken to avoid hypovolemic shock as these injuries tend to bleed a great deal.
Complications of Pelvic Fractures
The main complications are infection, which can be as high as 25 percent of all pelvic fractures. Thromboembolism can occur because of prolonged immobilization of the patient’s legs. Malunion can occur and nonunion is possible, depending on the fracture.
Death is possible with pelvic fractures. The statistics are as follows:
• Three percent die even if they are hemodynamically stable.
• Up to 40 percent die if they are not hemodynamically stable.
• The greatest cause of death is a head injury
• Another major cause of death is pelvic and visceral injuries.
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