A pelvic fracture is a break in one or more of the bones in the pelvis. This includes the sacrum, coccyx, ilium, ischium, and pubis. The type of pelvic fracture a person has may depend on the trauma impact, which can range from mild to severe.

The pelvis is the area of the body directly below the abdomen, located between the hip bones. It consists of two parts: the pelvic spine and the pelvic girdle. The pelvic spine comprises the sacrum, a triangular-shaped bone, and the coccyx, also known as the tailbone. The pelvic girdle consists of three fused bones: the ilium, ischium, and pubis.

The pelvis aids movement and provides attachment for muscles, tendons, and ligaments. A pelvic fracture is a crack or break in one or more of the bones that make up the pelvic ring. According to the American Academy of Orthopaedic Surgeons (AAOS), pelvic fractures are rare and account for about 3% of all adult fractures.

This article will provide an overview of the different types of pelvic fractures, including causes, treatment, and recovery.

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Because several bones make up the pelvis, trauma to the pelvis can affect any of the bones in the pelvic ring, resulting in a pelvic fracture. The affected bone will determine the type of pelvic fracture. A fracture may also involve one or more pelvic bones.

Evidence indicates pelvic fractures occur in around 37 out of 100,000 individuals annually in the United States, with the highest incidence in those aged 5–28 years.

The types of pelvic fractures include:

Ilium fractures

The ilium, the most extensive part of the pelvis, is round and flat. A fracture can occur anywhere on the bone. A fracture to the ilium can also vary depending on the severity of the injury.

A person with this kind of fracture may have:

  • limited motion
  • swelling and bruising on the skin
  • sharp pain in the hip or groin

Ischium fractures

The ischium bone lies directly below the ilium. It forms a ring-shaped structure with the pubic bone, allowing the passage of nerves and blood vessels to and from the lower limb.

An ischium fracture is most likely to occur due to a fall or accident. It can prevent a person from placing extra weight on the affected hip. Symptoms of ischium fracture may range from mild to severe and can include:

Pubis fractures

Repetitive stress or collision can break the pubic rami — a group of bones forming part of the pelvis. Pubis fractures are the most common pelvic fracture among older adults. They can be painful, affecting a person’s mobility.

Acetabulum fractures

The acetabulum is the socket on each side of the pelvis. An acetabulum fracture rarely happens unless someone experiences a blunt impact, such as falling from a significant height or a car accident. Acetabulum fractures may damage bones and soft tissues in the hip or pelvis.

Stress fractures

Like other parts of the body, stress can cause tiny cracks in the pelvic bone. Cumulative, repetitive forces from overuse, such as continuously running long distances or repeatedly jumping up and down, can cause a pelvic stress fracture. Stress fractures can also develop from the everyday use of bones affected by osteoporosis.

Stable and unstable fractures

These terms refer to the number of breaks in the pelvic ring and how the bones align.

A stable fracture may cause a simple and single crack in the pelvis. They do not cause any form of displacement of the broken parts. This means that the bones still have the correct alignment. People typically sustain this type of fracture by engaging in low energy activities such as running or through minor falls.

An unstable fracture usually has two or more breaking points, resulting in a displacement of the pelvic bones. This occurs because the pelvic ring and the broken ends of the pelvic bone do not align correctly.

The AAOS notes that the following can cause a pelvic fracture:

Bone inefficiency

A weak or insufficient bone due to old age or osteoporosis can lead to pelvic fracture. In this case, the fracture occurs during routine activity such as walking up or down the stairs or getting in or out of the bathtub. Fractures from bone inefficiency do not typically cause any damage to nerves and deep blood vessels passing through the pelvis.

High energy trauma

Injuries from high energy trauma can be life threatening and may require surgical intervention. This includes high-energy force from:

  • a head-on car or motorcycle collision
  • falling from a distant height
  • severe accidents

Other causes

A piece of the pelvic bone may detach from the point of a tendon or ligament and cause a type of fracture that medical professionals call an avulsion fracture.

Before recommending a treatment plan, a doctor will consider the:

  • pattern of the fracture
  • level of displacement
  • overall condition

Treatment may include nonsurgical and surgical options. In some cases, a doctor may recommend walking aids and medications for stable fractures that are minimally displaced.

However, if a person has an unstable pelvis following a fracture, they may benefit from surgeries, including internal fixations and skeletal traction to hold the pelvic bones in place.

A person may generally not experience pain from a fractured pelvic bone unless they move the hip or attempt to walk.

Stable fractures usually resolve independently. A person may recover fully from an unstable fracture in 12 weeks.

A pelvic fracture describes a crack or break in the bones that make up the pelvis. These fractures can occur due to blunt trauma, bone inefficiency, or other causes.

As the pelvis consists of many bones, there are different types of fractures. A doctor can also classify a fracture depending on the number of breaks and how the bones align.