A new hip implant procedure for arthritis patients, developed in Birmingham, involving a 3 mm thick cup made of cross-linked polyethylene might be the solution for people who are allergic to the traditional metal cups.
The new method is called Polymotion Hip Resurfacing and the hip implant used in the procedure is made from the same type of plastic used in high-voltage cable insulation and offers a better alternative to the traditional metal implant.
The special plastic is normally used in industrial settings due to the fact that it is abrasion-resistant and does not melt. Studies show that plastic used for the implant will also not be causing any allergic reactions.
According to Mr. Derek McMinn, a consultant orthopedic surgeon ant BMI Edgbaston Hospital, the traditional hip implant method, known as metal-on-metal hip resurfacing uses a cobalt chromium alloy. Allergic reaction to metal may vary in severity, the worst situation being the death of surrounding hip muscle and permanent disability.
Another benefit that this new procedure has is that, unlike the normal hip replacement procedure where they replace the ball joint of the hip with a stemmed device and keep very little of the upper leg bone, the new procedure needs to have less bone removed.
The polyethylene doesn’t bond with, therefore the surface of the cup is covered with a layer of porous titanium that comes in contact with the bone in order to make the socket bone grow into the titanium, thus ensuring that the cup is welded to the skeleton.
Mr. McMinn says that one of the major benefactors of Polymotion Hip Resurfacing will be women due to the fact that they are more affected by metal allergies and also have a higher predisposition for a condition known as developmental dysplasia of the hips.
The fact that women tend to have shallow sockets makes it really difficult to position a cup in a resurfacing operation accurately. This is a serious matter because when it comes to metal-on-metal procedures the cup needs to be positioned properly otherwise it can cause increased wear of the components, resulting in a reaction due to particles leaching into the blood stream. Due to the polyethylene inside surface of the cup, the polymotion method has a reduced risk of causing this sort of reactions.
Several patients have already undergone the new procedure and suffered positive changes. One of the patients who had the new implant installed had an allergy to chromium which is a constituent of metal-on-metal hip components. The new plastic implant solved this problem.
the cost of the new procedure is around £13,000 and the good news is that it could eventually be available on the NHS.