Hip Replacement Devices and Their Development

A current hip resurfacing patients recently asked why it took surgeons so long to learn how important the angle of the acetabular cup angle is during hip resurfacing surgery. Incorrect placement of the acetabular cup has caused many failures of hip resurfacing resulting in revisions of hip resurfacing to total hip replacements.
The answer to that question of why it takes so long to learn if a hip device and/or surgical technique is successful takes a long time since it is complicated. Iif anyone has worked in the engineering or design field, they will realize that usually the original design of a product or machine is never what the final design turns out to be. We are not machines that can determine perfect designs for anything. There are always unknowns. If you think about many things in our lives, they are always under constant change and updates. Car models are often changing, TVs are changing, cell phones, computers, etc. are constantly in change. Software for computers are always updating and changing. Athletes are always changing techniques to improve their skills. Musicians are always practicing to improve their skills. Medicine and joint replacement is not any different. Engineers are trying to design a device to replace a human joint while doctors are trying to place that foreign object in our bodies to act as the original equipment. This is not an easy task. There have been thousands of designs of hip devices over the years. The metals or plastics continue to change, the metallurgy changes, and the designs of the components change. There is nothing static about designs, they are constantly changing.
It takes time for doctors to learn how the devices are actually functioning in patients. Typically it takes about three to four years for them to start to see trends about how the device has acted and how the bone growth has attached to the components. It takes time for the results to become statistics. So with any device, the wait period is long and often by then, there has been a change in the device design. As a result, there are few devices of the same design left after a few years to compare results.
It is very difficult tracking the new devices and their results right after their implant since it takes time for the bone to attach to the components. Many of the top experienced surgeons were placing the actabular cups at a good angle early on. They knew instinctively that the acetabular cup should be in a certain position to work well. I have always said and heard surgeons say that surgical skill is more than a skill or learned process, it is also an art. It is similar to the great athletes that instinctively know what to do. They do learn and practice, but have a God-given skill that places them way above many other athletes. The same is true with the really top surgeons. If you think about sports or activities you are personally really good at, you are not looking at the educational videos or books to learn how to throw a ball, play an instrument or type on a computer. Those with really good skills are able to do it almost without thinking. That is the way it is with the top surgeons. They had an instinct about how things should work and were very successful. Mr. McMinn of the UK is doing that all the time as he develops devices. Many of the other top surgeons have helped develop hip devices and many of the surgical instruments to help place hip devices. A recent example of one is with Dr. Kusuma in Columbus. He wanted a better way to insure his placement of a BHR was correct. He developed a template system which no other surgeon had done before.
There is a great deal of constant change with any hip device or any man-made mechanical device. Designs keep changing and hopefully for the better. Skills and instruments to place joint devices keep changing and hopefully for the better. It is very complex and just takes time to develop excellent devices and how to place them exactly. The orthopedic surgeons keep track of their series of hip resurfacings and the National Directories keep track of hip resurfacing patients. It takes time for all the statistics and results to accumulate and become tools to help learn about a hip device and a specific surgical technique.


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