Depuy Synthes EXPEDIUM SFX Handbuch Seite 10

UNION OR NONUNION. Internal fixation appliances are
load-sharing devices that are used to obtain alignment
until normal healing occurs. If healing is delayed, or does
not occur, the implant may eventually break due to metal
fatigue. The degree or success of union, loads produced
by weight bearing, and activity levels will, among other
conditions, dictate the longevity of the implant. Notches,
scratches or bending of the implant during the course
of surgery may also contribute to early failure. Patients
should be fully informed of the risks of implant failure.
3. MIXING METALS CAN CAUSE CORROSION. There are
many forms of corrosion damage and several of these
occur on metals surgically implanted in humans. General
or uniform corrosion is present on all implanted metals
and alloys. The rate of corrosive attack on metal implant
devices is usually very low due to the presence of passive
surface films. Dissimilar metals in contact, such as stainless
steel and Cobalt-Chromium-Molybdenum or Cobalt-Nickel-
Chromium-Molybdenum, accelerate the corrosion process of
stainless steel and more rapid attack occurs. The presence
of corrosion often accelerates fatigue fracture of implants.
The amount of metal compounds released into the body
system will also increase. Internal fixation devices, such as
rods, hooks, etc., which come into contact with other metal
objects, must be made from like or compatible metals.
4. PATIENT SELECTION. In selecting patients for internal
fixation devices, the following factors can be of extreme
importance to the eventual success of the procedure:
A. The patient's weight. An overweight or obese patient
can produce loads on the device that can lead to failure
of the appliance and the operation.
B. The patient's occupation or activity. If the patient is
involved in an occupation or activity that includes heavy
lifting, muscle strain, twisting, repetitive bend ing,
stooping, running, substantial walking, or manual labor,
he/she should not return to these activities until the bone
is fully healed. Even with full healing, the patient may
not be able to return to these activities successfully.
C. A condition of senility, mental illness, alcoholism, or
drug abuse. These conditions, among others, may
cause the patient to ignore certain necessary limitations
and precautions in the use of the appliance, leading to
implant failure or other complications.
D. Certain degenerative diseases. In some cases, the
progression of degenerative disease may be so advanced
at the time of implantation that it may substantially
decrease the expected useful life of the appliance. For
such cases, orthopedic devices can only be considered
a delaying technique or temporary remedy.
E. Foreign body sensitivity. The surgeon is advised that no
preoperative test can completely exclude the possibility
of sensitivity or allergic reaction. Patients can develop
sensitivity or allergy after implants have been in the
body for a period of time.
F. Smoking. Patients who smoke have been observed to
experience higher rates of pseudarthrosis following sur-
gical procedures where bone graft is used. Additionally,
smoking has been shown to cause diffuse degeneration
of intervertebral discs. Progressive degeneration of
adjacent segments caused by smoking can lead to late
clinical failure (recurring pain) even after successful
fusion and initial clinical improvement.
PRECAUTIONS
1. SURGICAL IMPLANTS MUST NEVER BE REUSED.
An explanted metal implant should never be reimplanted.
Even though the device appears undamaged, it may have
small defects and internal stress patterns that may lead to
early breakage. EXPEDIUM SFX Cross Connectors must
not be reused once they have been final-tightened; use a
new connector if repositioning is necessary.
2. CORRECT HANDLING OF THE IMPLANT IS EXTREMELY
IMPORTANT. Contouring of metal implants should only be
done with proper equipment. The operating surgeon
should avoid any notching, scratching or reverse bending
of the devices when contouring. Alterations will produce
defects in surface finish and internal stresses which may
become the focal point for eventual breakage of the
implant. Bending of screws will significantly decrease the
fatigue life and may cause failure.
3. CONSIDERATIONS FOR REMOVAL OF THE IMPLANT
AFTER HEALING. If the device is not removed after the
completion of its intended use, any of the following
complications may occur: (1) Corrosion, with localized tissue
reaction or pain; (2) Migration of implant position resulting in
injury; (3) Risk of additional injury from postoperative trauma;
(4) Bending, loosen ing, and/or breakage, which could
make removal impractical or difficult; (5) Pain, discomfort,
or abnormal sensations due to the presence of the device;
(6) Possible increased risk of infection; and (7) Bone loss
due to stress shielding. The surgeon should carefully weigh
the risks versus benefits when deciding whether to remove
the implant. Implant removal should be followed by adequate
postoperative management to avoid refracture. If the patient
is older and has a low activity level, the surgeon may
choose not to remove the implant thus eliminating the risks
involved with a second surgery.
4. ADEQUATELY INSTRUCT THE PATIENT. Postoperative
care and the patient's ability and willingness to follow
instructions are among the most important aspects of
successful bone healing. The patient must be made aware
of the limitations of the implant, and instructed to limit and
restrict physical activities, especially lifting and twisting
motions and any type of sports participation. The patient
should understand that a metallic implant is not as strong
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