Total Hip Replacement (Total Hip Arthroplasty)

Indications

A total hip replacement is a surgery that replaces a damaged hip joint with artificial parts. It is most often done to relieve pain and improve movement in people with severe hip arthritis. It may also be recommended for people with a hip fracture that hasn’t healed properly (called a nonunion) or for those with bone death (avascular necrosis) in the top of the thigh bone (femoral head). There are also patients who have suffered a femoral neck hip fracture that may benefit from a hip replacement, particularly if they are younger, very active, or have notable existing hip arthritis.

Procedure

Overview

The artificial hip joint includes three parts (Figure 1): a new socket (acetabulum), a smooth ball (femoral head), and a stem that fits into the thigh bone (femur). The ball and socket work together to allow smooth movement, just like a healthy hip.

Figure 1: X-ray of a total hip replacement (arthroplasty)

• Femoral Component: The thigh bone is prepared by hollowing out space for the stem. The metal stem can be attached with bone cement or pressed into place so bone grows around it over time.
• Femoral Head: A smooth metal or ceramic ball is placed on top of the stem. This ball replaces the worn-out femoral head and fits into the new socket.
• Acetabular Component: The new socket usually has a metal outer shell and a plastic or ceramic inner cup. It is attached to the pelvis using either screws, cement, or a press-fit technique that encourages bone growth.

These artificial parts move smoothly together to copy the function of a healthy hip. Different materials and surgical techniques may be used depending on the patient’s needs and the surgeon’s preference.

Prosthetic Components

The femoral part has a stem (inserted into the femur) and a head (the ball). The acetabular part (socket) goes into the pelvis and often includes a metal shell with a smooth liner inside made of plastic, ceramic, or metal. The surface where the ball and socket meet is called the “bearing surface.” Common combinations include:

• Metal-on-Polyethylene: Most common. This is the tried and true “bearing surface.” Over many years it may wear down, but generally is very effective for years.
• Ceramic-on-Polyethylene: Creates less friction than metal, reducing wear.
• Ceramic-on-Ceramic: Used in younger, more active patients. Lasts longer but may make a squeaking sound.

Fixation of the Hip Replacement: Cemented vs. Uncemented

Hip implants can be attached to the bone using cement or left uncemented so the bone grows around them. Sometimes, a mix of both is used.

• Cemented Fixation: Bone cement, often methyl methacrylate, acts as a grout to bind the prosthesis to the bone. It provides immediate stability and allows for quick weight bearing following hip replacement surgery. It has been used for years, and many studies have demonstrated a high success rate even after many years. However, the cement may break down over time.
• Uncemented Fixation: Often used in younger patients with strong bones. It takes time for bone to grow around the implant, so weight-bearing may be delayed following hip replacement surgery. However, it has the advantage of avoiding any potential breakdown of cement over the years.

Surgical Approaches Used in Performing a Hip Replacement

Total hip replacements can be performed using a few different techniques to create a window to “approach” the hip joint. Each surgical approach has their own risks and benefits. The technique that is used depends on the preference and experience of the surgeon, as well as what will best suit the patient undergoing surgery. In general, different techniques require disruption of different muscles, tendons, and ligaments in the body. Although these structures heal with time, they may never fully return to their original condition. The three main approaches to a hip replacement are as follows:

• Posterior Approach: Most common. Good for complex cases. Provides good view but may have slightly higher risk of hip dislocation after surgery.
• Lateral Approach: Patient lies on their side. Offers good visibility of the hip joint but involves cutting through some of the muscles on the side of the hip which may affect walking pattern afterward.
• Anterior Approach: Less muscle cutting, faster recovery. However, it’s technically harder and less commonly used.

Recovery

Recovery starts right after surgery. Patients are encouraged to walk with a cane or walker within a day or two. Gradually, more weight is placed on the hip until walking without help is possible. Blood thinners and compression stockings help prevent blood clots. Physical therapy is important to build strength and prevent hip dislocation. Following instructions carefully helps ensure a good outcome.

Potential Complications

Like any surgery, hip replacement has some risks. These may include:

• Surgical site infection
• Deep vein thrombosis and pulmonary embolism
• Failure of the prosthesis
• Leg-length discrepancy, or one leg being shorter than the other
• Loosening of the prosthesis
• Hip dislocation
• Heterotopic ossification, or bone formation in a place where it is not supposed to be

Edited by Stephen Pinney MD, August 4th 2025.