Birmingham Hip Modular Head (used in hip replacements)
High revision rate
30 October 2012
The Birmingham Hip™ Modular Head (BHMH), manufactured by Smith & Nephew, is a component of a metal-on-metal (MoM) total conventional hip replacement system that consists of a Birmingham Hip™ Acetabular Cup, a Birmingham Hip™ Modular Head and a conventional femoral stem (see diagram below).
Health professionals and patients are advised that data collected by the Australian National Joint Replacement Registry (NJRR) and other registries shows that the BHMH has a higher than expected revision rate. The NJRR identifies Metal Sensitivity and Loosening/Lysis as the most significant reasons for revisions.
It is important to note that this advice does not relate to the Birmingham Hip™ Resurfacing (BHR) implants, which continue to have a low revision rate when compared with other hip resurfacing implants.
The TGA closely monitors all MoM hip replacement systems.
Patients with MoM hip replacements are encouraged to review the TGA statement: Metal-on-metal hip implants: Information for patients.
If you are not sure what type of hip replacement you have or if you have concerns about your hip replacement, you should seek information from the surgeon who performed the operation or the hospital where the operation was performed.
If you have a MoM hip replacement and have pain in your hip or thigh, you should consult your general practitioner (GP) and/or your orthopaedic surgeon. Your GP/surgeon will usually order X-rays and may in some instances order further tests such as ultrasound, MRI and blood tests.
Each patient’s circumstances are different and the TGA cannot give individual clinical advice regarding the BHMH.
The TGA recommends that surgeons contact patients who have received the BHMH and inform them of this alert.
Furthermore, surgeons are advised to review the TGA’s guidelines for MoM hip replacement implants and the Arthroplasty Society of Australia guidelines.
Smith & Nephew has issued a hazard alert to implanting surgeons who have previously used the component.
The BHMH is no longer available for primary hip replacement surgery. Smith & Nephew have stated in the instructions for use that BHMH should only be used for revision of BHR implants where a Birmingham Hip Acetabular Cup is well fixed and positioned, where there are no signs of metal sensitivity, and the femoral component is to be revised to an uncemented Synergy stem.
Patients with any hip replacement should be followed up by the implanting orthopaedic surgeon if possible, particularly if the patient complains of pain and other symptoms associated with their hip implant and surgery.
The TGA monitors the safety and performance of orthopaedic implants using data collected by the NJRR since 2006. This and other recent hazard alerts relating to hip replacement implants have arisen from the TGA’s routine processes involving close analysis of the NJRR annual reports, together with review of internal incident reports and consideration of external specialist advice.
The annual reports of the NJRR, and detailed information about implants that were identified as having higher than expected revision rates going back a number of years, are available on the NJRR website.
The observation by the NJRR that the revision rate for the BHMH is high and increasing is also supported by the National Joint Registry of England and Wales (NJREW). The revision rate for the system is generally good until the third year of implantation, when revisions for metal sensitivity and infection in particular occur at a greater frequency than for other total conventional hip replacements. According to the NJRR, the Cumulative Percent Revision for BHMH at 3 years is 3.1% compared to 2.8% for other total conventional hip implants. However the Cumulative Percent Revision for BHMH at 7 years is approximately 9% compared to 5% for other total conventional hip implants. The NJRR reports that cumulative incidence of revisions due to metal sensitivity for BHMH is approximately 0.01% at 1 year, 0.4% at 3 years and then rises steeply to 1.5% at 5years and 2.4% at 7 years.
There have been 39 different types of conventional stems used with the BHMH. Its revision rate with all stems is:
- 1.29 (95% CI 1.11, 1.49) revisions per 100 observation years in the NJREW
- 1.13 (95% CI 0.94, 1.34) revisions per 100 observation years in the NJRR.
The revision rate in the NJREW exceeds the UK’s National Institute for Health and Clinical Excellence’s 1% benchmark. The revision rate in NJRR should be compared to the 0.81 (95% Cl 0.79, 0.83) revisions per 100 observation years reported for all other total conventional hip replacements.
The femoral stem used most often in Australia in conjunction with BHMH (approximately 25% of the primary BHMH cases) is the Smith & Nephew uncemented Synergy femoral stem. The rate of revision of the BHMH/Synergy stem combination is 1.07 (95% CI 0.88, 1.27) in the NJREW and 0.94 (95% CI 0.65, 1.33) in the NJRR.
The BHMH is not to be confused with the Birmingham Hip™ Resurfacing (BHR) implants, which continue to be acceptable with 0.73 (0.67, 0.80) revisions per 100 observation years compared to the group average of 1.07 (1.00, 1.14) in the NJRR.
Patients and health professionals are encouraged to report problems with medical devices. For more information see the TGA Incident Reporting and Investigation Scheme (IRIS).
The TGA cannot give personal advice about an individual’s medical condition. You are strongly encouraged to talk with a health professional if you are concerned about a possible adverse event associated with a medical device.
Web page last updated: Wednesday, 31 October 2012
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