Acetabular Fracture

Overview

The acetabulum is the cup-shaped socket of the pelvis into which the ball of the thigh bone (femoral head) fits, forming the hip joint. An acetabular fracture is a break in this socket. Because the acetabulum is deep within the pelvis and bears much of the body's weight, these fractures are serious and can affect how the hip joint works for years afterward.

Acetabular fractures most often result from high-energy impacts such as car crashes or falls from a height in younger people, and from lower-energy falls in older adults with weaker bone. They frequently occur alongside other injuries, so a careful, whole-body evaluation is important.

Symptoms

The main symptom is severe pain in the hip, groin, or buttock, especially with any movement or attempt to bear weight. Other signs include:

• Inability to stand or walk on the affected side
• Swelling and bruising around the hip and upper thigh
• The leg appearing shortened, rotated, or held in an abnormal position
• Numbness, tingling, or weakness in the leg if nearby nerves are affected

Because these fractures come from forceful injuries, there may also be signs of damage elsewhere. Severe pain after major trauma, an inability to move the leg, or signs of significant blood loss require emergency care.

Causes

An acetabular fracture happens when a strong force drives the head of the thigh bone into the hip socket. Common causes include:

• Motor vehicle collisions: The knee striking the dashboard can push the femur into the socket.
• Falls from a height: Landing forces transmit up through the leg into the pelvis.
• Falls in older adults: Even a standing-height fall can fracture weakened bone.
• Sports and crush injuries: Less common, but high-impact accidents can cause these breaks.

In people with osteoporosis or bone weakened by other conditions, far less force is needed to cause a fracture.

Risk Factors

• High-energy activities such as driving, sports, or work at heights
• Older age and osteoporosis
• Conditions or medicines that weaken bone
• Poor balance or frequent falls
• Previous pelvic or hip injury

Diagnosis

Doctors diagnose an acetabular fracture using examination and imaging, often as part of a broader trauma assessment:

• X-rays: The first test to confirm a fracture and show its general pattern.
• CT scan: Provides detailed images of the fracture lines and any displaced fragments, which guides treatment planning.
• Assessment for other injuries: Checking the bladder, blood vessels, nerves, and other bones, since these fractures often come with additional damage.

Mapping the exact fracture pattern is important because it determines whether surgery is likely to be needed.

Treatment

Treatment depends on how displaced the fracture is, whether the joint surface is involved, and the person's overall health.

• Non-surgical care: Fractures that are stable and well-aligned may heal with limited weight-bearing, pain control, and measures to prevent blood clots.
• Surgery: Displaced fractures often need an operation to realign the joint surface and hold the bone with plates and screws, restoring a smooth socket.
• Hip replacement: In some older adults or when the joint is badly damaged, replacing the hip may be considered.
• Rehabilitation: Physical therapy gradually rebuilds strength, range of motion, and walking ability.

Recovery typically takes several months. Because the fracture involves a joint surface, some people develop hip arthritis later, which is monitored over time.

Prevention

• Always wear a seatbelt and use proper safety equipment at work and in sports
• Keep bones strong with adequate calcium, vitamin D, and weight-bearing exercise
• Get screened and treated for osteoporosis if you are at risk
• Reduce fall hazards at home, such as loose rugs and poor lighting
• Work on balance and strength, especially in older age

When to See a Doctor

An acetabular fracture is a serious injury. Call emergency services or go to an emergency department immediately after any significant fall or accident if you have severe hip or groin pain, cannot stand or walk, or your leg looks deformed. Seek emergency care right away for:

• Severe pain after high-impact trauma
• Inability to move or feel the leg
• Signs of heavy internal bleeding, such as dizziness, pale skin, or fainting
• Loss of bladder or bowel control

Prompt evaluation protects the hip joint and detects other injuries that often accompany this fracture.

Related Topics

Frequently Asked Questions

References

1. American Academy of Orthopaedic Surgeons (AAOS). Acetabular (Hip Socket) Fractures.
2. Mayo Clinic. Pelvic and hip fractures.
3. MedlinePlus, U.S. National Library of Medicine. Hip fracture.
4. OrthoInfo, American Academy of Orthopaedic Surgeons. Pelvic Fractures.