Metal hip implant recipients
are likely very aware of the problems associated with the cobalt and chromium
parts of the implant devices. The Stryker Rejuvenate and ABG II, both recalled
in July, 2012, are not true metal-on-metal hip implants, but have found to have
many of the same risks and dangers. The Rejuvenate and ABG II have a metal neck
juncture as well as small metal trundles located on the neck piece. When the
two models were recalled Stryker cited the risk of fretting, corrosion and
early implant failure.
When the metal parts of the
implant corrode, tiny metal particles can shear away from the implant,
burrowing into surrounding hip tissues or entering the bloodstream. Metal
toxicity can result from cobalt and chromium in the bloodstream and can have
very serious consequences. Neurological, cardiovascular, gastrointestinal,
renal and thyroid issues have all been found among those with high levels of
cobalt and chromium as well as depression, anxiety, irritability, DNA
disruption, vertigo, pseudotumor formation, vision and hearing loss and chronic
headaches and pain.
There are several tests to
measure the levels of cobalt and chromium in the bloodstream, including:
·
Inductively Coupled Plasma Mass Spectrometry
(ICP-MS)
·
High-Performance Liquid Chromatography
·
Field-Flow Fractionation (FFF)
·
Isotope/Metal Speciation
The ICP-MS test is faster,
more precise and more sensitive than the older atomic absorption tests and is
able to detect metal levels as low as one part per trillion. A blood sample
from the patient is ionized with inductively coupled plasma. A mass
spectrometer then separates the plasma in order to record the levels of metals
in the bloodstream. The high-performance liquid chromatography test may be used
to test for abnormal levels of cobalt and chromium among those with metal hip
implants. Chromatography consists of a mass transfer process which relies on
pumps to send the sample of blood through a silica-filled column. This
effectively separates the blood components from one another after which a
digital microprocessor provides the blood analysis.
FFF uses fluid suspension to
separate the blood sample as it is pumped through a long narrow channel. The
blood may be sent through an electrical, gravitational, magnetic, centrifugal
or thermal-gradient membrane in order to achieve separation. The resulting
fractogram identifies the various levels of metals in the bloodstream as well
as other species according to physical and chemical properties. Isotope/metal
speciation can be used to measure levels of hexavalent chromium in the body.
Remember that trivalent chromium is necessary for the normal function of the
human body however hexavalent chromium is extremely toxic to the human body,
potentially leading to cancer.
The recalled Stryker Rejuvenate
and ABG II both have been found to have the potential to send cobalt and
chromium into the body, causing a wide variety of adverse health symptoms.
Patients who have chronic pain in the hip joint or notice any inflammation in
the area should see their physician as soon as possible to undergo blood tests,
MRIs and x-rays. Should the hip fail, revision surgery—both riskier and more
complex than the original surgery—will be necessary.
