Hip Resurfacing

What Is Hip Resurfacing?

Hip resurfacing is a type of joint replacement that aims to replaces the just the worn cartilage and bone immediately under the cartilage with an artificial ball and socket. Hip resurfacing is thought to be more respectful of a persons’ native hip joint, its movements and forces because less bone needs to be cut away.  It is performed in a similar manner to total hip replacement but it is quite a different operation. Modern hip resurfacings are made from ceramic or metal.   

Did you know there is nothing new about hip resurfacing?

The concept has been around for over a century.  When Sir John Charnley made the first successful and generalisable total hip replacement he actually set out to make a hip resurfacing. The load on a hip resurfacing is very demanding and the materials used weren’t durable enough.  Sixty years on technology has come a long way.

Is it better than a total hip replacement?

Don’t forget a total hip replacement is an excellent operation. This is especially true when a total hip replacement is performed taking into account a persons’ spinopelvic alignment, unique hip anatomy, and using an approach that allows less pain and faster return to function, such as the anterior approach. Total hip replacement dramatically reduces pain, improves function, and drastically improves quality of life. For older people, quality of life might mean being able to put on your shoes, walk without a cane, or go for a walk without having to stop to let the joint pain settle. On the other hand, quality of life for younger people might mean being able to run, surf or play demanding hip sports like football, tennis or martial arts, or work in physically strenuous jobs. This is where hip resurfacing may offer an advantage over total hip replacement surgery. In science this is called a ‘ceiling effect’, and it represents the upper limit of what can be achieved from an operation. We think the ‘ceiling’ for patient outcomes after hip resurfacing is higher than for total hip replacement.

There are some other benefits to hip resurfacing. If you need to have a “re-do” or a revision, it can often be converted to a regular total hip replacement because less bone has been cut way in the first place. While surgeons are hopeful the first operation will be the only operation required, it is an important consideration because people who choose to have a hip resurfacing is good for are often younger. Dislocation of a hip resurfacing is almost unheard of.

There are two other trends we see if we look at studies of hip resurfacing. One is that people who have a hip resurfacing live longer. You might say that’s because comparing apples and orange, people who have a hip replacement are older and sicker than young fit active people who have a hip resurfacing. The trend for longer life remains even if we adjust for age and medical illness, or even compare the same groups of people having the two different types of hip surgery.

The other trend that is interesting is that hips with a resurfacing get less infection than those with a total hip replacement. This makes intuitive sense because bacteria can “hide” from the bodies’ immune system on artificial joints. If there is less surface area for bacteria to hide it makes sense there is less infection.

How is it done?

Hip resurfacing surgery is performed in a similar manner to total hip replacement surgery. It all begins with a careful history, examination and imaging. Based on this we can figure out your goals and native hip joint shape and decide whether a total hip or hip resurfacing is better suited for you. We use special x-rays to assess the alignment of your spine and pelvis and a CT scan to measure the shape of your hip and legs to do 3D preoperative planning to come up with an alignment that is ideal for your body. The surgery can be performed by all the standard approaches to the hip. After making cuts in the skin and the hip joint the arthritic surface is removed so that the artificial parts can be inserted. Great care is taken to repair the parts of the hip that were cut for access. After surgery you will stay in hospital 3-5 days, this is different for everyone and on balance slightly longer than the hospital stay for an anterior approach total hip replacement. The rehabilitation is different too. There is more emphasis placed on Phase 1 of Rehab: Healing. This is because more soft tissue is released in order to do a hip resurfacing and this needs to be permitted to heal. The first four weeks are slower to allow this healing, and by eight weeks after your surgery you should progress to Phases 2 and 3 – motion and strengthening. 

Are there any problems with hip resurfacing?

There are problems with any operation, especially operations that put in and leave in an artificial part, and hip resurfacing is no different. The main problem with a ceramic hip resurfacing is that we only have “short-term results”. Some total hip replacements in the Australian National Joint Replacement Registry have data out to 25 years post surgery Results for ceramic hip resurfacing results are out to 10.

So far ceramic hip resurfacings are performing very well. Firstly, we are not seeing the same early problems we saw with the last generation of hip resurfacings, the metal on metal. Secondly, the rate of problems is very low. Breakage of the material is rare. We are not seeing the early failures in “high risk” patients that we did with the last generation of hip replacements.

The most common problem would be noise generated by the two ceramic surfaces rubbing on each other. We call this a ‘squeak’. We think this occurs when the two surfaces move against each other unevenly. The loudness varies from something only the person with the ceramic hip can hear, to a louder noise similar to a timber chair being pushed on a timber floor.

What are they made from?

The new generation of hip resurfacing parts are made out of a ceramic called Biolox Delta. Ceramics are the hardest and smoothest material used to make joint replacements. This ceramic is widely used for conventional total hip replacements. Biolox Delta has the lowest fracture rate and noise production of any of the ceramics available. It has now been adapted to use in hip resurfacing.

Prior to ceramic being available hip resurfacings were made from metal. These have mostly been successful. A downside of metal hip resurfacings was that they were not very forgiving. If they were not aligned the edges would rub on each other unevenly and generate very fine metal particles. These particles would get into the bloodstream and create a lot of inflammation that would then damage nearby bone, tendons and muscles. Those metal particles getting into the blood stream and affecting other organs has always been a worry, but difficult to prove. Because of these dramatic complications very few metal resurfacings are now done. When they are done it is usually in patients that will benefit the most and by surgeons very experienced in performing the surgery. 

Should I have a hip resurfacing or hip replacement?

There is no simple answer to this question. Whether you should have a total hip replacement or hip resurfacing depends on your values, your goals, your level of function and your individual hip anatomy. I would be delighted to go over each of these points carefully and guide you in this decision.