Hip Dislocation

First aid for a suspected hip dislocation

• Call 911. Hip dislocations from trauma often come with other serious injuries.
• Keep the person still in the position found, supported with pillows or blankets.
• Do not try to straighten, pull or reposition the leg.
• Do not give food or drink, as sedation or surgery will be needed.
• Keep them warm and reassure them.

How the hip dislocates

The hip is a deep ball-and-socket joint held by strong ligaments and muscles. In a natural hip, dislocation needs a large force, which is why it usually occurs with fractures of the socket, femoral head or thighbone.

Symptoms

• sudden, severe pain in the hip and groin
• inability to move the leg or bear weight
• the leg looks shorter and is rotated in or out
• a bulge in the buttock or groin
• numbness, weakness or foot drop if the sciatic nerve is stretched (posterior dislocation)

Associated injuries

• Acetabular fracture (socket wall)
• femoral head or neck fracture
• femur fracture and knee injuries from the dashboard
• sciatic nerve injury in about 10 to 20% of posterior dislocations
• injuries to the head, chest, abdomen and spine in car crashes

Diagnosis

• Examination of the leg position, pulses and nerve function before and after reduction
• X-rays of the pelvis and hip to confirm the dislocation and look for fractures
• CT scan after reduction to check for small fractures or bone fragments trapped in the joint
• MRI later to assess cartilage, labrum and blood supply if needed

Treatment

Reduction

The hip is put back into place as soon as possible, ideally within 6 hours, under deep sedation or general anesthesia. Delays raise the risk of the femoral head losing its blood supply. If the hip cannot be reduced by manipulation (closed reduction), surgery is needed.

After reduction

• CT scan to confirm a concentric joint and check for fragments
• Surgery for socket or femoral head fractures, trapped fragments or an unstable joint
• Protected weight-bearing with crutches or a walker for several weeks
• Hip precautions to avoid positions that cause re-dislocation, especially after posterior dislocation
• Physical therapy to restore strength, range of motion and walking
• Blood clot prevention medicines while mobility is limited

Prosthetic hip dislocation

Most dislocated hip replacements can be reduced without surgery. Repeated dislocations may need revision surgery to reposition components, use larger heads or dual-mobility implants, or repair soft tissues. Follow your surgeon's movement precautions, especially in the first 6 to 12 weeks after surgery.

Complications

• Avascular necrosis: loss of blood supply causes the femoral head to collapse, sometimes appearing up to 2 years later. Risk rises sharply with delayed reduction.
• Post-traumatic arthritis: common, especially with fractures.
• Sciatic nerve injury: foot drop and numbness; many recover partially over months.
• Re-dislocation: more common after hip replacement.
• Heterotopic ossification: extra bone forming in the muscles around the hip.
• Blood clots in the legs.

Recovery and outlook

Uncomplicated traumatic dislocations generally take 2 to 3 months to heal, with full recovery of strength over several months. Recovery is longer with fractures or nerve injury. Long-term follow-up with X-rays or MRI checks for avascular necrosis and arthritis, which may later require hip replacement.

Frequently asked questions

What are the signs of a dislocated hip?

Signs include sudden severe hip pain, inability to move the leg or stand, a leg that looks shorter and is turned inward or outward, and sometimes a bulge in the buttock. Numbness or foot weakness suggests nerve injury. It is an emergency.

How does a hip become dislocated?

In a natural hip, dislocation usually requires a high-energy impact, such as the knee hitting a dashboard in a car crash or a fall from height. After hip replacement, it can happen with ordinary movements like bending too far or crossing the legs.

How long does it take to recover from a hip dislocation?

Uncomplicated dislocations usually take about 2 to 3 months to heal, with several more months to regain full strength. Recovery takes longer if there are fractures or nerve injuries. Physical therapy is an important part of recovery.

Can a dislocated hip pop back in on its own?

Occasionally a replaced hip may slip and relocate on its own, but it should still be checked. A traumatic hip dislocation does not go back without medical treatment and must be reduced urgently under sedation or anesthesia.

What is the most common type of hip dislocation?

Posterior dislocation is the most common, accounting for about 90% of traumatic hip dislocations. It usually happens when the knee strikes the dashboard in a car crash, pushing the thighbone backward out of the socket.