BHR vs ASR  Hip Prostheses by Dr. Bose

We, orthopedic surgeons find it difficult to weed out commercial promotional jargon from scientific data. I sure appreciate how difficult it would be for patients! Regarding the comparison of devices, the BHR was the original device and the others are copies of it. The BHR presently has a 9 year clinical history.

Smith and Nephew    Dupey ASR 

BHR                     

The 35 years history of some metal on metal hip replacements  (Ring & Mckee  Faraar) was the major catalyst that  led to the development of the BHR  and the Birmingham  designers took great care to duplicate the metal and clearances of the historical devices so that they can draw on the 35yr history. All other devices are deviances from the historical metal on metal THR devices and thus cannot draw on that history.

All other devices have a very short clinical history. Every manufacturer naturally will claim that their device is the best and will quote varied reasons substantiating their claim. However , in any kind of joint replacement surgery , the track record is the most important feature and must be given exceptional importance. It is quite opposite of choosing a car, where the latest model is probably the best. The performance of a prosthesis when implanted may be quite different from lab tests. One can always exchange the car if it does not perform well but unfortunately in joint replacement  things are not so simple!

The ASR (as all other prosthesis ) have claims of superiority on lab testing. This is completely different scenario from how the implant behaves after implantation in a patient. Only time will tell as to which of these will work and which will fail.

Depuy (manufacturer) claims that the ASR is better because it is  thinner than the BHR. Another manufacturer claims exactly the opposite  i.e. that their product is thicker than the BHR and hence superior. Their opinion is that the thicker component serves the resurfacing cause better. The same goes for stem. Some of the new designs have smaller design claiming less stress shielding and some other have longer and thicker stems claiming to  splint the neck of femur avoiding a fracture risk.

Thus you will find people changing some characteristics of the gold standard BHR and claim superiority.  Some of these changes may indeed be good. However only time will tell whether they are desirable changes or fatal mistakes.

The history of orthopaedic surgery is littered with similar cases. One of the most important and well known is the Exeter THR stem which currently has  the best results of a cemented hip replacement and can be considered to be the Gold standard. The manufacturer/developer surgeons decided to alter the surface treatment into a matt finish from a polished one. This resulted in a  very high failure rate but it took 6-7 yrs for someone to work out the association. The Exeter stem then went back to its original polished stem. Who could a guessed that a surface finish of a non articulating part of a prosthesis would cause such a drastic change in results?

The responsibility of the surgeon is not confined to the surgery alone. Post op performance of the implant is also a surgeon's responsibility . This makes me cautious.

I am not a gambling man, hence I stick with the BHR. However, when the choice is not made by me , I do use other devices.  Patients have requested specific devices and i have used them. In other instances surgeons have asked me to use other  implants when I have gone over to  other centres to help them do resurfacing surgery and I have complied. I have nothing against other implants but no one can deny that they are a bit of a gamble.

Dr. Bose