Biomedical Engineering Reference
In-Depth Information
15.3.2 PEEK Anchors
The focus of anchor design is to find a suitable
material that will allow the anchor to be in service
until the tissue has healed. Anchors are subjected to
multiple submaximal loads in the in vivo environ-
ment
[41]
. PEEK has recently been introduced into
suture anchor devices, and its use can minimize some
of the drawbacks of metallic and bioabsorbable
anchors. One benefit of PEEK is that it can be drilled
through in the event that a revision surgery is
required
[39,42]
. Along with bioabsorbable materials
such as PLLA and PGA, PEEK has a distinct man-
ufacturability advantage over metallic anchors as it
can be injection molded. This allows the mass
fabrication of the complex geometries that are often
desired for anchor devices. PEEK is also radiolucent,
eliminating artifacts during CT or MRI. PEEK is
clearly advantageous over the other polymers in its
holding capacity and strength. Compared with bio-
absorbable polymers, PEEK poses less risk for eyelet
rupture and eliminates concerns stemming from
premature degradation and pull-out. In comparative
cyclical tests, various PEEK anchor designs have
performed well in terms of holding strength and in
some cases have exhibited “remarkably high” load
failure strengths, with a few designs being stronger
than the two high-strength sutures with which they
were loaded
[42]
. PEEK anchors also present less
risk in terms of an osteolytic response relative to
bioabsorbable polymers.
ACL in 2005, and 875,000 meniscal repairs, repre-
senting the two most common arthroscopic proce-
dures
[40]
. Interference screws are fully threaded
screw-type devices used to secure soft tissue auto-
grafts or allografts to the host bone. For interference
screws, the same technological drivers are present:
metal screws can complicate revision surgeries and
disrupt MRI scans
[43]
, and bioabsorbables suffer
from inflammatory and strength limitations
[43,44]
.
Drawing on similar advantages realized with PEEK
bone suture anchors, a number of PEEK interference
screws are currently available. PEEK devices indi-
cated for ACL tear repair include iFix (Cayanne,
Scottsdale, AZ), PEEK CF (Parcus Medical, Sturgeon
Bay, WI), Biosure Sync (Smith and Nephew, And-
over, MA), Bio-Intrafix (Depuy Mitek), and Exo-
Shape (MedShape Solutions, Atlanta, GA).
Figures
15.10 through 15.12
show examples of interference
screw-type devices commonly used for ACL repair.
Similarly, PEEK interference screws indicated for
tenodesis currently available include the Bio-Tenod-
esis screw (Arthrex), Biceptor (Smith and Nephew,
Andover, MA), and G-Force (Wright Medical,
Arlington, TN). There are also currently marketed
PEEK products for meniscal tear fixators, including
the Fast-Fix 360 (Smith and Nephew), the Omnispan
(Mitek), and the Cinch (Arthrex, Naples, FL).
15.4 Principles of Craniofacial
Defect Repair
15.3.3 Current Landscape for
PEEK Suture Anchors
There is a fast growing field of PEEK arthroscopic
anchors currently in use.
Table 15.1
shows a number
of differing anchors, along with basic characteristics
of each design.
Figures 15.5 through 15.9
show
anchors marketed by Parcus Medical (Sturgeon Bay,
WI), Depuy Mitek (Raynham, MA), Stryker (Mah-
wah, NJ), and MedShape Solutions (Atlanta, GA).
Craniofacial defects typically result from a plan-
ned craniotomy, trauma, infection, or oncological
resection for tumor removal
[45]
. For craniotomies,
large skull bone segments need to be removed due to
intracranial abscesses, epilepsy, or other disorders
when direct access to the brain is required. Large and
complex defects can affect a patient both cosmetically
and functionally
[46]
. When bone is removed, the
only remaining protection for the brain is the dura
mater, the subcutaneous tissue, and the scalp.
Seizures may occur as a secondary complication, and
there is an increased risk for meningitis
[47]
. Also,
there is an issue of intercranial dead space that can
result from the reexpansion and reconstruction of the
contours of the fronto-orbital region
[48]
. When there
is no closure of this dead space, there is a higher risk
of infection
[48]
. The loss of cranial bone can
be further exacerbated as a secondary complication
to postsurgical
15.3.4 PEEK Interference
Screws and Fixators
Utilizing similar functioning to suture anchors,
interference screws used for tenodesis, the repair of
torn anterior cruciate ligaments (ACLs) and posterior
cruciate ligaments (PCLs), and fixators for meniscal
tears have incorporated PEEK in some product lines.
There were over 250,000 procedures to repair a torn
infection and osteoradionecrosis.
