The sacrum is a bone at the back of the pelvis between the hip bones. A sacral fracture can cause symptoms including lower back and buttock pain, swelling, and reduced bowel and bladder control.

Although it is possible to fracture only the sacrum, most sacral fractures occur with other injuries.

Other injuries associated with sacral fractures include damage to the nerves that control a person’s:

  • bladder
  • bowels
  • reproductive organs
  • internal abdominal injuries

This article explains what a sacral fracture is, its symptoms, its causes, and how doctors diagnose it. It also looks into the treatment options available and self-care measures.

Broken glass.Share on Pinterest
Vicente Méndez/Getty Images

The sacrum is a wedge-shaped bone that sits at the back of the pelvis between the hip bones. Five vertebrae in a person’s spine fuse together to make this bone. They get progressively smaller toward the center, giving the bone its triangular shape.

The sacrum and hip bones make the pelvis a sturdy ring. Strong ligaments hold these bones in place. When a person fractures their sacrum, they usually break other bones in their pelvis and damage their ligaments.

A 2017 study claims only 5% of people with sacral fractures have a single injury. People with sacral fractures also commonly have pelvic ring injuries or spine or hip fractures.

Most sacral fractures occur due to motor vehicle accidents. However, older people may break their sacrum in minor falls, especially if they have osteoporosis.

Most people with a fractured sacrum experience lower back pain, but other symptoms depend on the injury type and severity.

Doctors describe sacral fractures as high-energy, low-energy (sometimes called insufficiency), and stress. Motor vehicle accidents and heavy falls from a height are examples of high-energy fractures. Athletes, particularly runners, may experience stress fractures without falling.

People with high-energy fractures may experience the following:

  • hip and buttock pain
  • reduced control of their bowels and bladder
  • pain, bruising, and swelling in the surrounding areas

People with low-energy and stress fractures often experience persistent lower back pain that worsens when moving around or lifting anything.

Most people fracture their sacrum during road traffic accidents. These include collisions, pedestrians hit by a vehicle, and motorcycle accidents.

Insufficiency, or low-energy, fractures happen when a person’s bones are not strong enough to support everyday activities. A 2017 observational study notes that older people who have tripped and landed on their buttocks may fracture their sacrum.

People with stress fractures have healthy bones but injure themselves by doing abnormally intense or overly repetitive exercises. These fractures are more common among younger female athletes who may have low bone density.

The most significant risk factor for a sacral fracture is a traumatic, high-energy injury involving other injuries.

Age plays a part in low-energy fractures. Evidence suggests that older postmenopausal women with osteoporosis have a high risk of developing sacral fractures. Generally, women are at higher risk than men for low-energy sacral fractures.

Athletes of all genders may fracture their sacrum during sporting activities. Sacral fractures are more common in runners, but they can happen to athletes of any sport.

Doctors need to treat any life threatening issues immediately in people with traumatic injuries. They will check for instability in the person’s pelvis and stop any bleeding.

Sacral fractures are difficult to diagnose and do not always appear on X-rays. CT and MRI scans may be more reliable.

Doctors may also recommend a rectal exam to check for nerve damage. These tests check that a person’s anal sphincter contracts properly and that there is no damage to the bundle of nerves that control these responses, called the cauda equina.

Treatment depends on the severity of a person’s additional injuries. Surgery is more likely if the fracture is due to a high-energy fall or a motor vehicle collision.

If the fracture is due to a lower-energy fall or is a stress fracture, doctors usually recommend rest and pain relief medication. However, a person should keep mobile, if possible. People with stress fractures from sporting injuries may need to avoid these activities for 6 weeks.

Doctors may also recommend calcium and vitamin D supplements.

If a person has damage to their pelvis, doctors may recommend surgery to stabilize it. They may use surgical screws, plates, or bone cement to hold it together.

Doctors may recommend surgery if a person has damage to their cauda equina. Surgical decompression of the nerves can increase a person’s chances of full recovery from nerve damage.

According to the American Academy of Orthopaedic Surgeons (AAOS), doctors may recommend walking aids, such as crutches, or a walker, to help older people with osteoporosis move around. They may also suggest simple leg and foot exercises before gradually building up to a person’s typical activity levels.

Some people find ice packs relieve discomfort and reduce swelling.

The AAOS also notes that diet plays a role in bone health and recovery. Calcium and vitamin D are essential, as well as other nutrients. A balanced diet may also reduce the risk of constipation.

Sacral fractures can take between 8–12 weeks to heal. However, this time may vary, depending on the extent of a person’s other injuries.

Most people recover fully, but some may have ongoing back pain.

People who have experienced nerve damage may have urinary, rectal, and sexual dysfunction.

Sacral fractures are rare and seldom happen in isolation.

Most people break their sacrum during a high-energy trauma, such as a car accident. Athletes can get fractures if their activities stress their bones, while older people may experience fractures if osteoporosis weakens their bones.

Treatments depend on the type of accident and any additional injuries the person may have.