Sacral Fracture

Overview

The sacrum is the large, triangular bone at the base of the spine. It sits between the two halves of the pelvis and helps transfer weight from the spine to the legs. A sacral fracture is a break in this bone. Because important nerves that control the legs, bladder, and bowel pass through and near the sacrum, fractures here can sometimes affect these functions.

Sacral fractures occur from high-energy trauma in younger people and from low-energy falls in older adults with weakened bone. They are sometimes missed at first because the pain can be mistaken for a simple back or tailbone injury, so a careful evaluation is important.

Symptoms

The main symptom is pain in the lower back, buttock, or tailbone area that worsens with sitting, standing, or walking. Other signs include:

• Tenderness, swelling, or bruising over the lower back and buttocks
• Pain when bearing weight or changing position
• Pain radiating into the back of the leg
• Numbness or tingling in the buttocks, groin, or legs
• Changes in bladder or bowel control in more serious injuries

Numbness around the groin and inner thighs or new bladder or bowel problems can signal nerve injury and need emergency evaluation.

Causes

Sacral fractures result from force applied to the lower spine and pelvis, or from weakened bone. Common causes include:

• High-energy trauma: Motor vehicle crashes and falls from a height, often along with other pelvic injuries.
• Low-energy falls: In older adults with osteoporosis, even a fall onto the buttocks can fracture the sacrum.
• Stress fractures: Repetitive loading, sometimes in athletes or in bone weakened by osteoporosis, can cause small insufficiency fractures.
• Disease: Cancer that has spread to the bone can weaken the sacrum.

Risk Factors

• Osteoporosis and older age
• High-impact accidents or falls
• Pelvic injury from major trauma
• Long-term steroid use
• Cancer affecting bone
• Repetitive high-load activity

Diagnosis

Doctors diagnose a sacral fracture with examination and imaging:

• X-rays: A first step, though sacral fractures can be hard to see on plain films.
• CT scan: The best test for showing the fracture pattern and any displacement.
• MRI: Useful for stress or insufficiency fractures and to assess nerve involvement.
• Neurological exam: Checking sensation, strength, and bladder and bowel function to look for nerve injury.

Because sacral fractures often accompany other pelvic injuries, a broader trauma assessment is common after high-energy accidents.

Treatment

Treatment depends on whether the fracture is stable and whether nerves are affected.

• Non-surgical care: Many stable sacral fractures heal with rest, pain control, limited weight-bearing, and gradual return to activity.
• Bone-strengthening treatment: For osteoporotic and insufficiency fractures, medicines, calcium, and vitamin D help reduce future fractures.
• Minimally invasive stabilization: In some cases, procedures that inject bone cement or place screws can reduce pain and stabilize the bone.
• Surgery: Unstable fractures or those compressing nerves may need surgery to realign the bone and relieve nerve pressure.
• Rehabilitation: Physical therapy rebuilds strength and mobility.

Recovery from stable fractures often takes several weeks to a few months.

Prevention

• Maintain bone strength with calcium, vitamin D, and weight-bearing exercise
• Get screened and treated for osteoporosis if at risk
• Reduce fall hazards and improve home lighting
• Use seatbelts and protective equipment
• Build balance and core strength, especially in older age

When to See a Doctor

See a doctor for persistent lower back, buttock, or tailbone pain after a fall, especially if it limits walking. Call emergency services or seek emergency care right away for:

• Numbness in the groin, buttocks, or inner thighs
• New loss of bladder or bowel control
• Severe pain after a major fall or crash
• Weakness or numbness in the legs

These can indicate injury to the nerves passing through the sacrum and need urgent treatment to prevent lasting problems.

Related Topics

Frequently Asked Questions

References

1. American Academy of Orthopaedic Surgeons (AAOS). Pelvic Fractures.
2. Mayo Clinic. Stress fractures and osteoporosis.
3. MedlinePlus, U.S. National Library of Medicine. Spinal and pelvic fractures.
4. National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). Osteoporosis.