GLENOID - POLYETHYLENE OR ‘BIOLOGICAL RESURFACING’?
Mr O Levy, Consultant Orthopaedic Surgeon, Royal Berkshire Hospital, UK
Presented at: International Shoulder Symposium - Leysin, Switzerland - 4-5 March 2005
There is no long term randomized study concerning whether a total or hemi-arthroplasty should be used. The most recent study by Gartsmann (using stemmed prostheses) indicated that the early results are better using a total shoulder replacement from the point of view of pain relief. However, the long-term failure rate of shoulder replacements relates to glenoid loosening due to ultra-high molecular weight polyethylene (UHMWPE) wear debris and mechanical wear. The decision to perform a hemi-arthroplasty is to accept the compromise of less good short-term pain relief against an expected improvement in long-term outcome. This decision is particularly critical when performing arthroplasty in young patients with high demands and a long life expectancy. In our unit, conversion of hemiarthroplasty (CSRA) to total replacement has only been required on 3 occasions.
We looked at the results in our series and found that there was little difference in the functional results and pain of those with and without a glenoid early as well as later after shoulder arthroplasty.
This may be due to the fact that with surface replacement we can mimic better the normal anatomy for each patient than with the stemmed prostheses and there is substantially less place for error in inserting the stem too proud, using smaller head size or in wrong version that may lead to glenoid erosion and less favorable result.
It is known that the long-term survival of any total joint replacement is related to the volume of UHMWPE wear debris, and therefore the use of UHMWPE should be avoided if possible.
Our current practice is to perform Copeland Surface replacement hemi-arthroplasties with ‘biological resurfacing’ of the glenoid. The glenoid articular surface is drilled with multiple 2 mm drill holes to encourage secondary fibro-cartilage growth, which we have confirmed by histologic examination of samples taken at subsequent arthroscopy.
Our current indications for a total joint arthroplasty are only non-concentric erosion of the glenoid, in elderly patients as long as the rotator cuff is intact (even then we will try biological resurfacing first - we would prefer to burr out the middle bony ridge and reshape the glenoid concentrically to accept the humeral resurfacing while preserving the structure of the hard ebornated ‘subchondral’ bone). To conclude, our current practice is to perform hemiarthroplasty with ‘biological resurfacing’ of the glenoid.