The Metal Bearing Surface: The Birmingham View Failures of Metal-Metal Bearings – would another bearing couple do better? Derek McMinn, BOA 2010
This lecture is from the British Orthopaedic Association (BOA) meeting in Glasgow in 2010. Derek McMinn presents information on some of the reasons behind failures of metal on metal bearings in replacement hip joints. The pre-existing conditions that can increase the risk of failure are explored as well as variables that may be incurred by the surgeon, for example edge wear due to high inclination angles. Further discussions look at different surgeons results using the same implants, hip resurfacing in women, Total Hip Resurfacing (THR) taper junction failure and the use of highly cross linked polyethylene.
Mr Derek McMinn MD FRCS talks about the failures of metal on metal bearings relating to the Birmingham Hip Resurfacing (BHR) and Total Hip Replacement (THR) implants. Metal debris caused by edge wear of an acetabular cup that has a high inclination angle can be cause for revision says McMinn. The presence of avascular necrosis (AVN), cysts in the femoral head and dysplasia are deemed to escalate the chances of implant failure.
Mr McMinn explains how periprosthetic tissue reactions are widely referred to as 'pseudotumours', a term that generalises rather a lot of different reactions to surgery. The recall of DePuy's ASR device by the MHRA was anticipated by Mr McMinn, who has been warning about said device since 2005 (See The Northern Lights Debate lecture here). Results from a range of surgeons using the Birmingham Hip Resurfacing (BHR) are compared with the same surgeons ASR results, with a particular focus on the presence of 'psuedotumours'.
The presentation covers the survivorship of Hip Resurfacing in women, implant head size and the importance of head to neck ratios, causes of 'pseudotumour' in metal on metal Total Hip Resurfacings and the failures of taper junctions due to corrosion and frictional torque. The history and future of polyethylene is discussed as an alternative to metal on metal, with a highly cross-linked polyethylene acetabular cup mooted as the possible way forward for hip resurfacing surgery.
The fifteen year results for Mr McMinn's first 1000 BHR patients, a look at the current status and future of hip resurfacing and an update on the development of Polymix, a highly cross-linked polyethylene hip resurfacing cup – are now available in Derek McMinns latest lecture BHR & Other Options.