What is Hip Arthroplasty (Replacement)?

Helpful Highlights

• Arthroplasty is the medical term for joint replacement surgery.

• There are two types of hip replacements - total and partial.

• There are two ways to attach hip replacements - uncemented and cemented.

• An orthopedic surgeon performs the hip replacement and will have many recommendations, including delaying surgery when warranted.

Hip replacement, also called total hip arthroplasty (or THA), is a surgical procedure to address hip pain caused by damage and deterioration in the hip joint. Hip replacement addresses hip pain and stiffness for people with arthritis (multiple types), avascular necrosis (osteonecrosis), or other forms of hip joint damage such as:

• Injuries, like a hip fracture or dislocation from a fall

• An injury that didn’t heal right

• Developmental hip dysplasia

• Degenerative disease

• Cancer

• Childhood (congenital) hip disorders

The surgery replaces one or both parts of the hip joint with artificial implants. The implant is designed to move just like a natural, healthy joint.  The goal of the procedure is to allow your loved one to resume daily activities and exercise with less pain and limitation.  About 370,000 total hip replacements happen every year in the U.S.

What is the hip?

The hip is a joint — a large ball-and-socket joint — that seats the top of the thigh bone (femur) into the pelvis. The femur has a “head” at its top that’s shaped like a ball (femoral head), which fits into the pelvic socket (acetabulum). The joint is kept in place by very strong ligaments, tendons, and muscles. The hip is the most flexible and free-moving joint in our body, as it has wide-range movement backward and forward, side-to-side, and can perform twisting motions.

Types of hip arthroplasty (replacement)

There are two major types of hip replacements.

• Total hip replacement (the most common type) replaces the proximal end of the femur (head of the thigh bone, or trochanter) and a portion of the pelvis (the hip socket, or acetabulum) with artificial parts (prosthesis). Typically, the artificial femur head is made of a strong ceramic or metal alloy and the artificial socket is made of polyethylene (an incredibly durable, medical-grade plastic). The artificial joint is used to replace the damaged or diseased joint.

• Partial hip replacement replaces the femoral head only. This is less common and typically done for people with certain types of hip fractures (such as a break at a location called the trochanter).

Types of implant attachments

• A press-fit (uncemented) prosthesis attaches with an advanced material of rough, porous surface that encourages new bone growth. The new bone grows into the spaces in the implant, holding it in place without the need for cement.

• A cemented prosthesis attaches with bone cement.

Both press-fit and cemented approaches work well to secure the implant. As hip replacement techniques have evolved over the years, the cement composition has improved, as have methods to encourage natural bone regrowth. 

For some hip replacements, the surgeon will combine methods. They might prefer to use cement on the femoral stem while using a press-fit attachment on the socket.

The surgeon who performs hip arthroplasty (replacement)

If a hip replacement is the best treatment, your loved one's healthcare provider will send them to an orthopedic surgeon for evaluation. This surgery is usually performed on adults after other therapies like walking aids, weight loss, medicines, and physical therapy have failed to make a difference.

There are various surgical approaches to hip replacement surgery, including minimally invasive options that may be appropriate for some people.

Recovery and rehabilitation after surgery are essential to restore mobility and functionality and return to activities with less pain.

Because all surgeries have risks, and prostheses can fail as time goes by, the surgeon may recommend delaying a hip replacement until more severe symptoms are present.