Total hip replacement Offers Many Choices in Devices and Surgical Approaches

By Patricia Walter 6/3/2013

Historically,  the first hip replacement was performed about 40 years ago and was called the Charnley hip apparatus. This device was named after Sir John Charnley, who performed the first hip replacement. Many advancement in techniques and type of implants have been developed since then. Many Devices similar to the smooth, polished stainless steel stem and a plastic socket which was cemented into place at that time. Now there is a large variety of implants available that are either cemented or not cemented for the bone to grow around the implant.

Cemented and Uncemented Hip Implant options

Cemented implants have a long track record and continue to do very well,  but most of the hip replacements done in United States currently are not cemented, but are inserted in the bone so that the bone grows into the implant anchoring them.

In the last 10 years, major improvements in the artificial bearing surfaces of implants have been approved for use in the U.S. The stem portion of most hip implants is made of titanium or cobalt/chromium-based alloys. They come in many different shapes and some have porous surfaces to allow for better bone ingrowth.

The ball femur portion of the implant and the acetabular cup socket are made of variety of materials which include:

• metal on metal (MoM)
• metal on plastic (polyethylene or UHMWPE)
• ceramic on plastic (UHMWPE)
• ceramic on ceramic (CoC)

It has become a matter of major discussion and decision between the patient and the surgeon as to which hip device will be best for the patient.  The technique and technological advances are also a matter of important decision such as hemi-resurfacing, minimally invasive surgery, anterior approach, posterior approach, etc.  The decision between metal on metal, titanium, metal and polyethylene and ceramic must be made.

The patient is often left wondering “Which is the best hip implant for me?” “Should I or should the surgeon decide about the type of implant and technique to be used on me?” “Is the latest and technique and implant best for me?”

The fact is that no one knows what the “best” implant is. Experts say that the ideal hip replacement implant is the one that allows for normal activities, normal motion, and last the patient’s lifetime.

It is also important to note that not everyone is a good candidate for all techniques and implants. The decision about which type of hip replacement to be done over another should be based on knowledge about its durability, use and drawbacks. The majority of newer implants or surgical techniques have shown to have patient specific or implant specific drawbacks.

For example, minimally invasive hip replacement with smaller incision is many a times detrimental in adequately placing implants. Ceramic-on-ceramic total hip replacement has shown squeaking in 1 to 2 percent of patients. Total hip resurfacing may work well for some people, but not in others and in certain groups may increase the risk of femur neck fracture. Currently, it can only be done with metal-on-metal bearing surfaces and not everyone is a good candidate for these bearing surfaces. That’s because metal-on-metal hip replacement has the potential downsides of allergy and hypersensitivity reactions –  which may occur in one out of 1,000 patients. There are also fears of elevated metal ion levels in the bloodstream that could potentially cause detrimental long-term health problems, but this potential problem is purely theoretical and has not been proved in humans despite decades of use.

The best way to choose the right implant for you is to discuss this with your surgeon. The surgeon would consider your age, gender, weight, lifestyle and severity of joint degeneration. The doctor will also look at necessary and possible range-of-motion with the implant, stability of the implant and wear-resistance of the materials in light of your physical and lifestyle activity considerations.

The best or right implant for you is the one which fits the following criteria:

• The implant has minimum track record of 10 years
• The surgeon has used the implant before
• The implant is fit to be used for your specific condition

Total hip replacement has proved to be successful  for patients for many years. Implants and technology shall continue to evolve, but the best implant for you can only be chosen after understanding the risks and benefits of it.