On 30 January 2012, following media reports about the concerns on increased failure rate of the metal-on-metal (MoM) hip replacement implants, the MHRA issued a statement stating that based on the evidence currently available, the majority of patients implanted with MoM hip replacements are at low risk of developing any serious problems; and more analysis is needed before any conclusions can be drawn and further advice given.
The main concerns regarding MoM implants relate to the observation that some patients may develop progressive soft tissue reactions to the wear debris associated with MoM articulations. The debris can cause soft tissue necrosis and adversely affect the results of revision surgery. In addition, a limited number of case reports in the medical literature have also suggested the potential for systemic effects of elevated metal ion levels resulting from device wear in MoM hip systems.
In fact, in August 2010, the Department of Health (DH) was informed by local supplier Johnson & Johnson (HK) Ltd, about a recall of MoM hip replacement systems - the Depuy ASR™ XL Acetabular Head System and Depuy ASR™ Hip Resurfacing System manufactured by Depuy Orthopaedics, due to a higher than expected revision rate at five years. According to Depuy, data from the National Joint Registry of England and Wales showed that the five year revision rate was approximately 12 percent for the ASR™ Hip Resurfacing System and approximately 13 percent for the Depuy ASR™ XL Acetabular System. According to the local supplier, some 40 patients had received the Depuy ASR™ hip replacement implants in both public and private hospitals in Hong Kong. All the hospitals concerned have been informed of the recall and the necessary follow up actions. So far, no adverse event report has been received.
While DH shall closely monitor the situation regarding MoM hip implant systems, including any new recommendations from other regulatory authorities, patients who have received these implants are advised to continue to follow-up with their orthopaedic surgeons. Those who experience any symptoms such as pain or swelling at the hip joint or leg should consult their surgeon for an examination as early as possible.
For details, please refer to the following MHRA website: http://www.mhra.gov.uk/NewsCentre/CON140854