Hip Replacement Surgery for Ankylosing Spondylitis

Reviewed by: HU Medical Review Board | Last reviewed: June 2022 | Last updated: July 2022

Ankylosing spondylitis (AS) can cause stiffness and pain in the affected joints. While the spine and sacroiliac joints are the most commonly affected areas, approximately 30% of people with AS experience hip involvement.1 When the hip is affected, the inflammation in the hip joint can cause significant pain and make walking and other activities difficult.

Some people with AS who have severe joint damage to the hip joint may have surgery to replace the hip joint, called a total hip replacement or hip arthroplasty.

How ankylosing spondylitis affects the hip joint

The chronic inflammation of AS can lead to the development of bone being formed between affected joints, called ankylosis or bony fusion. However, when the hips are affected by AS, the damage is different. Instead of the formation of new bone, AS in the hips wears away or erodes the hip joint, which destroys the joint. This can be disabling and painful, causing a significant reduction in the individual’s mobility and quality of life. Hip replacement can lead to a dramatic improvement in function and mobility.2

What’s involved in a hip replacement

The hip is a ball-and-socket joint. In a total hip replacement, both the head of the femur (the top of the thigh bone, or “the ball”) and the acetabulum of the pelvis (the “socket” part of the joint) are replaced with prosthetic devices. The damaged head of the femur (or femoral head) is removed and replaced with a metal stem that is placed into the hollow center part of the femur. A metal or ceramic ball is placed on this stem to create a new femoral head. The damaged acetabulum is removed and replaced with a metal socket, which may be screwed or cemented in place. A spacer made of plastic, ceramic, or metal is placed between the new head and the new socket for a smooth gliding surface. Most hip replacements are performed by orthopedic surgeons, specialists trained in diagnosing and treating joint problems, and the actual procedure generally takes just a few hours and is done under general anesthesia.3

Determining if a hip replacement is appropriate

To determine if someone needs a hip replacement, an orthopedic surgeon will perform a thorough evaluation, including medical history, physical examination, x-rays, and possibly, other tests like an MRI (magnetic resonance imaging). The surgeon will assess the functional limitations of the damaged hip as well as ask questions about how it is impacting the patient’s daily living. In some cases, surgery may not be appropriate, and the person may be referred to a physical therapist or medical doctor.3

Risks of hip replacement surgery

A total hip replacement is a common surgery, with more than 300,000 being performed annually in the U.S., and most are performed successfully without complications.3 However, all surgeries have risks, including3:

  • Risk of infection
  • Blood clots in the legs or pelvis
  • Dislocation of the replaced hip joint (the risk is highest in the first few months after surgery)
  • Loosening of the implant
  • Risk of bleeding

The surgeon should explain all risks and ways to prevent or reduce these risks with the patient prior to surgery.

After hip replacement surgery

After a recovery period, most people who have had a hip replacement experience a significant improvement in their mobility and a dramatic reduction of hip pain. The implant is sturdy and can last for many years with normal use and activity, although excessive activity or being overweight can speed up the normal wear. Doctors recommend avoiding high-impact activities such as running and jumping after a hip replacement. Activities that a person with a hip replacement can generally safely engage in include walking, swimming, golf, driving, hiking, biking, and dancing.3

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