A recent survey carried out by the British Orthopaedic Association has shown that large diameter MOM manufactured by producers other than DePuy are showing greater than anticipated failure rates. These range from a 21% revision rate at 4 years to a 49% rate at 6 years for the ASR XL device.
Concern has been expressed regarding the trunnion at the morse taper where the large diameter metal head attaches to the stem. Several revised examples showed damage but it was not clear whether this was from wear or corrosion or both. Other potential sources of problems include the bearing’s surface and the stem if uncemented (possible corrosion).
The way in which these components fail include loosening of the asetabular and femoral component or metal reaction with necrosis and soft tissue damage. Failures seem to be more frequent in females.
Patients present with pain and frequently have radiographic changes including loosening. Blood cobalt and chromium ions are often but not always elevated. MRI scans may show fluid collections, cystic and/or solid masses which have been previously described.
Advice to Patients
Patients with metal on metal bearing hip replacement should be followed up regularly for 5 years and probably for the life of the prosthesis. Based on the results presented, the use of large diameter metal on metal bearings in primary total hip replacements should be carefully considered and possibly avoided.
If you have had hip replacement Surgery and have been affected by the recent recall of ASR hip devices please contact Liam Moloney, Solicitor Naas on 045 898000 to know your legal rights. Please also log on to our website at www.moloneysolicitors.ie for further information regarding faulty hip implant devices