When a patient presents with endstage osteoarthritis of the hip, has pain that matches the radiographic changes, and has reached a point where they feel that something needs to be done, we discuss several factors. They can be broken down into the choice of operation, choice of approach, and choice of implant.
With regard to the type of procedure, endstage osteoarthritis is typically treated with a total hip arthroplasty but there has been renewed interest in surface replacement. We go through the pros and cons of each and more often then not perform a total hip arthroplasty because of the benefits.
With regard to approach, hip replacement can be done through an anterior approach, a direct lateral approach, or a posterolateral approach. All three have their pluses and minuses. The strengths of the anterior and lateral approach are a lower dislocation rate. The posterolateral approach is the one most commonly used in the United Stated but it does traditionally have a higher postoperative dislocation rate. This dislocation rate has been reduced to a value similar to the anterior and lateral approach by use of large heads and repair of posterior soft tissue structures.
With regard to bearing surfaces, there are three options: Metal against cross-linked polyethylene, metal-on-metal, and ceramic-on-ceramic. Again, all three have their pluses and minuses. In the United States in 2006, 80% of the market was metal against cross-linked polyethylene. An increasing number of hips are using metal-on-metal bearings, which accounts for approximately 15% of the market, and 5% of the market utilizes ceramic-on-ceramic. As I have noted in my previous blogs, there has been a recent increase in squeaking of ceramic-on-ceramic hips and this is thought to be due to impingement of the neck of the stem on the rim of the socket creating some damage to the ball portion of the joint and interference with subsequent joint lubrication and resultant squeaking. While this is typically not painful, it can be audibly annoying and often leads to revision if it is loud. Metal-on-metal allows for the use of very large heads which will increase stability, improve range of motion, and improve the wear characteristics of most metal-on-metal implants.
When you are contemplating hip replacement surgery, you should discuss with your orthopedic surgeon the choice of procedure, the type of approach he or she uses, and have an understanding of the various bearing surfaces available.
William P. Barrett, M.D.