Biomedical Engineering Reference
In-Depth Information
if biomechanical instability exists at the attempted
fusion site. Similar to the observations of Jockish et al.
[16] , the observed inflammatory response consists of
macrophages with some foreign body giant cells.
Lymphocytes, eosinophils, plasma cells d which
might be indicative of an immune component to the
host response d are not observed. Thus, particulate
debris in the ovine model is associated with a chronic
inflammatory host
implanted biomaterials in humans as preclinical
animal studies do not always predict human clinical
performance of implants.
During the course of the explant study, we used
decalcified/paraffin histological analyses to assess
the host response adjacent to 17 interspinous process
decompression (IPD) system devices (X-STOP
PEEK, Medtronic Spinal and Biologics, Sunnyvale,
CA) explanted from 12 patients. The X-STOP
response without an immune
PEEK devices were all explanted from the lumbar
spines from patients as part of a Condition of
Approval Study (COAST, “Treatment of Lumbar
Spinal Stenosis With X-STOP
component.
7.7 Biocompatibility of PEEK
ParticulatedX-STOP TM PEEK
Explant Studies
PEEK IPD in
Moderately Symptomatic Patients”) sponsored by
Medtronic Spine LLC. The X-STOP PEEK IPD
System is a titanium and PEEK implant used for the
treatment of symptoms of lumbar spinal stenosis
(LSS). LSS is the most common reason for back
surgery in people older than 65 years in the United
States. The IPD system device is placed between the
spinous processes at symptomatic lumbar spine
levels in patients with neurogenic intermittent clau-
dication secondary to LSS. As shown in Figs 7.7
through 7.9 , in the explanted PEEK X-STOP devices,
PEEK is used as the biocompatible radiolucent
polymeric biomaterial for the elliptical spacer that
interfaces with bone of the spinous processes. The X-
STOP PEEK System has been in clinical use in
Europe since 2004. St. Francis Medical Technolo-
gies, the original developer of the X-STOP System,
first launched the PEEK version, which was approved
for European markets in March 2004. The Food and
Drug Administration (FDA) approved the X-STOP
PEEK System in August of 2006. Device explants
present a unique opportunity to study the biological
The primary purpose of our explant (human
retrieval) study is to evaluate the host response to
retrieved spine devices by performing histological
analyses on periprosthetic tissues removed during
explant surgery. The retrieval analysis study at the
Medical College of Wisconsin is set up to handle
retrieved devices and tissues associated with retrieved
devices. Retrieval analysis is covered under the
expedited Investigational Review Board (IRB)
Protocol entitled, “Histologic Evaluation of Retrieved
Spine Devices” (MCW HRRC 239-03). Our retrieval
analysis study is designed to evaluate the type of
tissues adjacent to retrieved devices, look for the
presence or absence of wear debris, and characterize
the inflammatory response adjacent to the device and
debris (if present). Retrieval studies supplement what
is learned from the patient's pathology report, but are
not in lieu of pathology [19] . Retrieval studies are
a unique opportunity to assess the host response to
Figure 7.7 X-STOP PEEK Interspinous
Process Distraction
(IPD ) System
explant.
Search WWH ::




Custom Search