Revised: 3 October 2012
An alert has gone out to surgeons in New Zealand implanting hip devices to advise that the Birmingham Hip Modular Head (BHMH) is no longer recommended for total hip replacement surgery.
Smith and Nephew, a UK company, says its Birmingham Hip Modular Head is not performing as well as expected when used in total hip replacement surgery.
NZ joint registry records show that of the 468 implants supplied to New Zealand, 396 have been registered for use in total hip replacements.
Metal-on-metal implants, including the BHMH, have only been used in 8% of the total hip implants during the last decade.
The implants affected to date represent less than 1.7 per cent of the nearly 71,000 hip replacements done in this country in the past 11 years.
This is the fourth worldwide action relating to the use of metal-on-metal implant components, starting with De Puy ASR in 2010 (525 devices in New Zealand), and earlier in this year, the Mitch TR (41), and the Smith and Nephew R3 (139).
Medsafe, New Zealand medicines and medical device regulator, says Smith and Nephew are contacting surgeons in New Zealand to notify them of this Alert and ask them to contact affected patients. Advice will include the need for greater monitoring of patients with these implants.
However Medsafe Group Manager Dr Stewart Jessamine says many patients with these implants and other metal-on-metal implants will not be affected by this or other alerts.
"The alert does not mean patients with the implant will necessarily require revision surgery, however, as a precaution patients with this implant will be followed up more frequently by their doctor."
"If patients experience any discomfort or pain they should see their GP or surgeon as they normally would following any surgery on a joint.
Medsafe will follow-up with the NZ suppliers to ensure specialists have been contacted and patients notified.
The Smith and Nephew Birmingham Hip Modular Heads were first used in NZ in 2005.
The Birmingham Hip Modular Head is a Metal on Metal (MoM) replacement system that consists of a Birmingham Acetabular cup, a conventional stem and a Birmingham modular head.
Smith and Nephew have issued this alert as joint registries in New Zealand, United Kingdom and Australia are all reporting these modular heads as having higher revision rates than for other orthopaedic implants.
The NZ overall revision rate of 1.51 revisions per 100 component years is comparable with the UK (1.29) and Australia (1.13) The slightly higher reporting rate for the NZ data is a consequence of the relatively small number of patients treated with this device in this country.
This action does not affect the Birmingham Hip Resurfacing implants which are performing to expectation.
There is a heightened awareness worldwide of possible higher revision rates in such devices.
Information about joint implants and revisions is collected by a register run by the New Zealand Orthopaedic Association: http://www.nzoa.org.nz
Information for consumers about metal-on-metal implants has been published on the Medsafe website at www.medsafe.govt.nz/profs/device-issues.asp#17April2012 and made available to surgeons.