What are hip replacements made of?

Hip replacement surgery has become a common and effective treatment for individuals suffering from chronic hip pain and mobility issues due to arthritis. In this article, we will discuss what hip replacement surgery entails, the different methods used in the procedure, the materials used for hip implants and how long hip replacements typically last.

What is hip replacement surgery?

Hip replacement surgery is a procedure in which a damaged or diseased hip joint is replaced with an artificial joint, also known as a hip implant. This surgery is performed to alleviate pain, improve mobility and enhance the overall quality of life for individuals suffering from various conditions, such as arthritis, avascular necrosis or congenital deformities.

For an in-depth look at the factors leading to hip replacement are read my article: Hip Replacement: What Causes The Need For Surgery?

During the surgery, an orthopedic surgeon removes the damaged parts of the hip joint, including the femoral head (the ball-shaped part of the thigh bone) and the acetabulum (the socket in the pelvic bone). These components are then replaced with artificial parts made from various materials which we will discuss later in the article.

What are the different types of hip replacement methods?

There are several surgical approaches used to perform hip replacement surgery. Each approach has its own advantages and disadvantages. The choice depends on factors such as the surgeon's expertise, the patient's anatomy and the specific needs of the case. The main surgical approaches for hip replacement surgery include:

1. Posterior approach: The posterior approach, also known as the Moore or Southern approach is the most commonly used method for hip replacement surgery. In this approach, the surgeon accesses the hip joint through an incision made on the back (posterior side) of the hip. The advantage of the posterior approach is that it provides good visualization of the hip joint, allowing for easier placement of the implant components. However, this approach involves cutting through some of the muscles and tendons in the hip area, which can lead to a longer recovery period and a slightly higher risk of hip dislocation after surgery compared to other approaches.

2. Anterolateral approach: The anterolateral approach, also known as the Watson-Jones or Hardinge approach, involves making an incision on the side (lateral side) of the hip. This approach provides good access to the hip joint and avoids cutting through the major gluteal muscles at the back of the hip, reducing the risk of hip dislocation. However, the anterolateral approach does still require cutting through some of the muscles and gluteal tendons at the side of the hip, which can lead to a longer recovery period and potential issues with hip abductor strength.

3. Direct anterior approach: The direct anterior approach, also known as the Smith-Petersen or Hueter approach, involves making an incision at the front (anterior side) of the hip. This approach is considered to be much less invasive than the other two methods, as it allows the surgeon to access the hip joint by going between the muscles, rather than cutting through them. This can result in a faster recovery time and reduced risk of hip dislocation. However, the direct anterior approach can be technically more challenging for the surgeon, as it provides a more limited view of the hip joint and may require specialized equipment and training.

What are hip implants made of?

Hip implants are made from a variety of materials, chosen for their durability, biocompatibility, and ability to mimic the function of a natural joint. The most common materials used for hip implants include:

1. Titanium: The majority of hip replacement components are made from titanium. This metal is strong, lightweight, and biocompatible, meaning it is less likely to cause adverse reactions within the body. Titanium is often used for the stem of the implant, which is inserted into the femur, as well as for the acetabular component.

2. Cobalt-chromium alloys: These strong and corrosion-resistant metals are sometimes used for the femoral head and acetabular components. Metal-on-metal implants used to be implanted using cobalt-chromium surfaces but have since fallen out of favor due to recalls.

3. Ceramic: Ceramic materials, such as alumina or zirconia, are often used for the femoral head component of the implant due to their excellent wear resistance and biocompatibility. Ceramic components can be paired with a ceramic or polyethylene acetabular liner.

4. Polyethylene: This type of medical-grade plastic is commonly used for the acetabular liner, the part that forms the socket in the artificial joint. It provides a smooth, low-friction surface for the femoral head to glide against.

Metal-on-metal hip replacements were once more commonly used, but concerns about longevity and potential complications led to a decline in their use.

Nowadays, metal-on-polyethylene and ceramic-on-polyethylene pairings are most common.

How long do hip replacements last?

The longevity of a hip replacement depends on various factors. These factors include the materials used, the patient's age, activity level, and overall health. In general, hip replacements have a high success rate, with many patients experiencing significant pain relief and improved mobility for 15 to 20 years or more.

However, it is important to note that artificial joints can wear out over time, potentially requiring revision surgery to replace the worn components. Factors that can contribute to the wear and tear of a hip replacement include:

1. Patient's age: Younger patients tend to be more active, which can result in faster wear of the artificial joint. In addition, younger patients may require multiple revision surgeries throughout their lifetime.

2. Activity level: High-impact activities and sports can place additional stress on the hip implant, potentially shortening its lifespan.

3. Body weight: Excess body weight can increase the load on the hip joint, leading to faster wear of the implant components.

4. Implant materials and design: The choice of materials and the design of the implant can also affect its longevity. For example, newer materials and designs may offer improved wear resistance and durability compared to older models.

To maximize the lifespan of a hip replacement, patients should follow their surgeon's recommendations for postoperative care, participate in physical therapy, and maintain a healthy lifestyle. Regular follow-up appointments with the orthopedic surgeon can help monitor the condition of the implant and identify any potential issues early on.

Is Hip Replacement Right For You?

Hip replacement surgery is a valuable treatment option for individuals suffering from chronic hip pain and mobility issues. Understanding the procedure, the different methods used, and the materials that make up hip implants can help patients make informed decisions about their treatment options. While the longevity of a hip replacement can vary, many patients can expect their new joint to last for 15 to 20 years or more with proper care and follow-up. By working closely with their healthcare team and maintaining a healthy lifestyle, patients can maximize the benefits of their hip replacement and enjoy a greater quality of life.