I prefer to use delta ceramic (large diameter, 36mm) head with highly cross linked polyethylene cup.

Thank you Dr. Vaishya, 

In my practice I also prefer this material combinaion (only the diameter of the head is usually 32 mm).

Panayot,

Yes , I would agree there still is siginificant debate over ceramic  on ceramic bearings. As you know from my design and clinical evaluation experience I do not operate but do get asked almost weekly what combination of bearing material do I recommend. I also get the opportunity to review and publish clinical findings.

My current recommendations on patients with less than 15 years of expected life (where cost might be an issue )  would be on moderate cross-link poly with C.C. head 32 or 36 mm. Patients with moderate to high activity with greater than 15 years of expected life would be Delta Ceramic again with moderate cross-link poly. I also prefer to see a minimum of 6 mm of poly material in the weight bearing contact areas.

Ceramic on ceramic has had good to excellent results, however are prone to more complications if any malpositioning is present. I also like ceramic heads versus C.C. heads used with titanium stems to avoid or reduce galvanic corrosion issues.

We are seeing more head/neck taper issues and the bearing selection should be a careful selection process. I prefer 12/14 head neck tapers as compared to smaller tapers like 11/13 and would not advocate any head larger than 36 mm regardless of material selection.

As you know wear is not an issue with ceramic on ceramic but hard on hard bearings are subject to other failure modes.

If cost was not an issue I would advocate ceramic on poly routinely. 

Regards,

Tim

In view of the higher costs and extreme wear resistance of ceramics, we commonly use ceramic bearings in young and active patients. This is the patient population for whom the wear reduction achieved with ceramics is likely to have the most enduring benefits. 

It follows that we do not prefer to use ceramic bearings for elderly and infirm patients, whose longevity or activity level is limited. These patients will derive no particular benefit from a ceramic bearing system and are better suited for a traditional metal-polyethylene bearing couple, which almost certainly will outlast them. 

Active and young patients I agree that they will be better off to have a Ceramic on Ceramic Delta articulation as a hard on hard surface has a longer survivorship. High cross-linked poly with ceramic is better in moderately young, active patients and in elderly I will still think that the use the traditional metal on cross-linked has good results and is preferred for financial purposes. The size of the head is determined from the thickness of the liner which is placed in the acetabulum. There are people that for the shake of a potential easier revision they use high cross-linked poly than ceramic liner. If a hard on hard surface is used (ceramic on ceramic) the orientation of the cup has to be precise as "squicking" is a possible complication in case of "malposition".

I agree with all comments presented so far however I do want to caution that this issue is now broader than just wear of the bearing surface. We are seeing taper issues arising that are effecting the performance of bearing material. I am attaching some photos of a recent explanted Accolade  femoral hip stem made of TMZF.

This proprietary beta titanium alloy offers 25 percent greater flexibility than Ti-6Al-4V alloy, yielding a modulus of elasticity that more closely resembles that of bone. In addition, TMZF maintains a 20 percent higher tensile strength than Ti-6Al-4V alloy.

This greater flexibility has presented problems with the neck/head taper. You will see in the photos attached that the stem taper has deformed resulting in lost contact of the femoral head. This material used with larger femoral offset and larger head diameter has contributed to device failure.

So the lesson learned is to be diligent in product selection and make sure you have the best information available. ( Errors are made by all manufactures regardless of size or longevity of the company).

Regards,

Tim

Thank you, Tim, for the example presented. This is a good lesson to learn. In any case  a head neck taper of 12/14 size is preferable. In the past we used a taper size 14/16 (Etropal) but there were problems with the ceramic heads of smaller diameter (26 mm). So we abandoned this type of stems. 

Ceramic on ceramic seems interesting but as previously said the complication rate is significant. I had a bad experience with one them, one year ago in US: the cup broke up and I still do not understand why. So I got back to my previous choice: delta ceramic with moderate cross-link poly, heads 32-36 (I haven't definitely decided). Probably the advantages of CERAMIC are marginal, whatsoever we may sometimes read.

Anyway, once more, a very good question and useful answers...

All the best to U all!

Thank you, Dr. LEVI-FAICT.

My experience is that over the past 20 years poly is getting so much better that probably ceramics, both liner and head side, could be limited to very diligently selected cases.