According to a study in bmj.com, the risk of developing cancer
within the first seven years after receiving a metal-on-metal hip
replacement is no higher than in the general population, although
further long-term studies are required.
BBC Newsnight and the BMJ recently investigated potentially high
levels of toxic metals from failing hip implants that could affect
thousands of people worldwide in the future. The authors also
investigated as to why these hip replacements were permitted,
regardless of the fact that the risks have been known and documented for
decades. Buy Levothroid Synthroid pills online without prescription
The investigation was commissioned by the National Joint Registry of
England and Wales, which contains over one million procedures from more
than 97% of orthopedic units, and executed by researchers from the
Universities of Bristol and Exeter, who investigated the validity of
these concerns. To evaluate the success rates of joint implant patients,
the registry data and hospital statistics are linked each year.
The authors decided to compare cancer rates in patients with
metal-on-metal hip replacements with patients with other types of hip
implants, as well as with the general population. 40,576 registered
patients in total, i.e. 14% had some kind of metal-on-metal bearing
surface, whilst 21,264 patients or 7% had a stemmed metal-on-metal
prosthesis and 19,312 patients or 7% had a resurfacing procedure.
The authors compared patient outcomes by using mathematical models that
included the patient's age and sex, as well as three measures of the
patient's general health at the time of hip surgery, i.e. the American
Society of Anesthesiologists grade, which scores the patient's other
serious illnesses, the number of NHS funded hospital admissions within
the previous five years as well as the number of distinct diagnostic
codes recorded at time of surgery.
According to the authors, a comparison between hip replacement patients
with people in the general population is not really straightforward,
given that hip replacement patients "tend to be healthier than others of
the same gender and age group".
The outcome of the study demonstrated that the likelihood of a 60 year
old man of moderate health and a metal-on-metal stemmed hip replacement
will be diagnosed with cancer five years after surgery is 6.2% as
compared with a likelihood of 6.7% in men with hip replacements that
contain other bearing surfaces. In women, these figures were 4.0% and
4.4% for other bearing surfaces respectively.
The findings furthermore reveal that the incidence of diagnosed cancers
after hip replacements is low, whilst that predicted for the age and sex
of the matched general population is lower.
The authors believe that their study will assist clinicians in
reassuring their patients that the "risk of cancer for hip replacement
patients is relatively low" and that there is no evidence that
metal-on-metal hip replacements pose a higher risk of cancer.
The authors recognize that the results only include findings for up to
seven years after surgery and recommend that further long-term data
analyses will be performed over the next few decades, given that this is
the lead-time for some cancers to develop.
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