Patients with metal-on-metal
hip implants are likely aware of the issues and recalls surrounding some
models. Stryker recalled two of its all-metal hip implants, the Rejuvenate and
ABGII in July, 2012. At the time of the recall Stryker declined to comment on
the exact failure rate of the implants, however cited fretting, corrosion and
the risk of metal debris in the body as reasons for the recall. Metal-on-metal
implants were designed with longer wear in mind—the companies claimed from ten
to fifteen years. Unfortunately, these claims did not pan out as adverse
reports began coming in to the FDA only a short time after the Rejuvenate and
ABGII were marketed in 2009.
When the metal parts of the
all-metal hip implants rub against one another, there is the potential for
metal debris to shear away, traveling through the body. Those metal shards can
travel to the surrounding hip tissues or may find their way to the bloodstream.
Some patients have been found to have a unique histological response to these
all-metal implants termed ALVAL (aseptic lymphocyte dominated vasculitis
associated lesion). This hypersensitivity may have a connection to bone
dissolution or misalignment of the implant. Any type of misalignment can result
in additional wear on specific parts of the implant and this additional wear
can cause metal ion generation.
Most of those who suffer from
ALVAL cannot complete a straight leg raise without experiencing extreme pain.
Fluid aspirated from the hip region of those suspected of having ALVAL is generally
thick and greenish-grey in color although there is no infection involved. ALVAL
is not completely understood, however when a patient suffers from persistent
groin pain yet infection is ruled out, ALVAL may be to blame. Many physicians
believe ALVAL is under-diagnosed as the symptoms can be non-specific and
systemic. Revision surgery will generally be indicated for patients with ALVAL
with a different type of hip implant material.
Metallosis in a patient with
an all-metal hip implant occurs when a foreign substance—in this case metal
ions produced by friction of the hip implant—enter the tissues of the body. The
body’s immune system sends macrophages into the body to fight the metal ions,
trapping them and preventing them from spreading. The body is, however, unable
to remove metal shards and the result is inflammation, pain, tissue and muscle
destruction and death and bone loss. The longer these metal ions remain in the
body the more likely the patient is to suffer from a variety of adverse health events.
While it appears some people
have a higher tolerance for metal build-up in the body than others, in the end
there really are no safe levels of cobalt and chromium in the human body. The
longer the cobalt and chromium are allowed to remain in the body the higher the
likelihood of a total hip failure, fracturing of the hip bone, severe levels of
infection or loosening of the implant—all events which will require revision
surgery. Symptoms of metal poisoning can
also occur in Stryker Rejuvenate and ABGII hip implant recipients and can
include any of the following:
·
Thyroid and kidney issues
·
Gastrointestinal disorders
·
Cardiovascular and neurological issues
·
Skin disorders
·
Loss of vision and hearing
·
DNA disruption
·
Nerve damage
·
Elevated cancer risks
·
Impaired liver function
·
Reproductive system problems
·
Anxiety, irritability and depression
·
Vertigo
·
Formation of pseudo-tumors
Many of those with
significantly elevated metal levels could be symptom-less until the cobalt and
chromium levels are extremely high. One orthopedic surgeon, Dr. Antoni Nargol,
noted that certain patients with no pain and normal x-rays were found to have “a
horrendous amount of metal debris and the cups have been loosened by the metal
and the metal debris gets behind the cup…and goes deep into the pelvis and has
blown holes in the pelvis.” For this reason, all those with a Rejuvenate or
ABGII hip implant should have regular blood testing done in order to monitor
the levels of cobalt and chromium in their bloodstream.
