[Federal Register Volume 60, Number 192 (Wednesday, October 4, 1995)]
[Proposed Rules]
[Pages 51946-51962]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-24686]
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DEPARTMENT OF HEALTH AND HUMAN SERVICES
Food and Drug Administration
21 CFR Part 888
[Docket No. 95N-0176]
Orthopedic Devices: Classification, Reclassification, and
Codification of Pedicle Screw Spinal Systems
AGENCY: Food and Drug Administration, HHS.
ACTION: Proposed rule.
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SUMMARY: The Food and Drug Administration (FDA) is proposing to
classify certain unclassified preamendments pedicle screw spinal
systems into class II (special controls), and to reclassify certain
postamendments pedicle screw spinal systems from class III (premarket
approval) to class II. FDA is also issuing for public comment the
recommendations of the Orthopedic and Rehabilitation Devices Panel (the
Panel) concerning the classification of pedicle screw spinal systems,
and the agency's tentative findings on the Panel's recommendations.
After considering any public comments on the Panel's recommendations
and FDA's proposed classification, in addition to any other relevant
information that bears on this action, FDA will publish a final
regulation classifying the device. This action is being taken because
the agency believes that there is sufficient information to establish
special controls that will provide reasonable assurance of its safety
and effectiveness.
DATES: Written comments by January 2, 1996.
ADDRESSES: Submit written comments to the Dockets Management Branch
(HFA-305), Food and Drug Administration, rm. 1-23, 12420 Parklawn Dr.,
Rockville, MD 20857.
FOR FURTHER INFORMATION CONTACT: Mark N. Melkerson, Center for Devices
and Radiological Health (HFZ-410), Food and Drug Administration, 9200
Corporate Blvd., Rockville, MD 20850, 301-594-2036.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. Highlights of the Proposal
II. Background
III. Recommendations of the Orthopedic and Rehabilitation Devices
Panel
IV. FDA's Tentative Findings
V. Summary of Data Upon Which FDA's Findings are Based
VI. References
VII. Environmental Impact
VIII. Analysis of Impacts
IX. Comments
I. Highlights of the Proposal
FDA is issuing for public comment several recommendations of the
Panel concerning the classification of pedicle screw spinal systems.
The Panel recommended that FDA classify into class II the unclassified
preamendments pedicle screw spinal system intended for the treatment of
severe spondylolisthesis (grades 3 and 4) of the fifth lumbar vertebra
in patients receiving fusion by autogenous bone graft having implants
attached to the lumbar and sacral spine with removal of the implant
after the attainment of a solid fusion. The Panel also recommended that
FDA reclassify the postamendments pedicle screw spinal system intended
for degenerative spondylolisthesis and spinal trauma from class III to
class II. For all other indications, pedicle screw spinal systems are
considered postamendments class III devices for which premarket
approval is required. The Panel made its recommendations after
reviewing information presented at two public meetings on August 20,
1993 and July 23, 1994, and after reviewing information which was
solicited in response to an April 3, 1995, letter. FDA is also issuing
for public comment its tentative findings on the Panel's
recommendations. FDA is proposing to expand the intended uses of the
device identified by the Panel to include pedicle screw spinal systems
intended to provide immobilization and stabilization of spinal segments
as an adjunct to fusion in the treatment of acute and chronic
instabilities and deformities, including spondylolisthesis, fractures
and dislocations, scoliosis, kyphosis, and spinal tumors. Finally, FDA
is proposing to codify the classification of both the preamendments and
the postamendments device in one regulation. Comments received in
response to this proposed rule, along with other relevant information
that the agency may obtain, will be relied upon by the agency in
formulating a final position on each of the foregoing issues and
provide the basis for a final agency regulation.
II. Background
The Federal Food, Drug, and Cosmetic Act (the act), as amended by
the Medical Device Amendments of 1976 (the 1976 amendments) and the
Safe Medical Devices Act of 1990 (the SMDA) established a comprehensive
system for the regulation of medical devices intended for human use.
Section 513 of the act (21 U.S.C. 360c) established three categories
(classes) of devices, depending on the regulatory controls needed to
provide reasonable assurance of their safety and effectiveness. The
three categories are as follows: Class I, general controls; class II,
special controls; and class III, premarket approval. Devices that were
in commercial distribution before May 28, 1976 (the date of enactment
of the amendments) are classified under section 513 of the act (21
U.S.C. 360c) after FDA has: (1) Received a recommendation from a device
classification panel (an FDA advisory committee); (2) published the
panel's recommendation for comment, along with a proposed regulation
classifying the device; and (3) published a final regulation
classifying the device. A device that is first offered for commercial
distribution after May 28, 1976, and is substantially equivalent to a
device classified under this scheme, is also classified into the same
class as the device to which it is substantially equivalent.
A device that was not in commercial distribution prior to May 28,
1976, and that is not substantially equivalent to a preamendments
device, is classified by statute into class III without any FDA
rulemaking proceedings. The agency determines whether new devices are
substantially equivalent to previously offered devices by means of the
premarket notification procedure in section 510(k) of the act (21
U.S.C. 360(k)) and part 807 of the regulations (21 CFR part 807).
The pedicle screw spinal system intended for indications other than
severe spondylolisthesis is a postamendment device classified into
class III under section 513 (f) of the act (21 U.S.C. 360c(f)). In
accordance with sections 513(e) and (f) of the act and 21 CFR 860.134,
based on new information with respect to the device, FDA, on its own
initiative, is proposing to reclassify this device from class III to
class II when intended to provide immobilization and stabilization of
spinal segments as an adjunct to fusion in the treatment of acute and
chronic instabilities and deformities, including spondylolisthesis,
fractures and dislocations, scoliosis, kyphosis, and
[[Page 51947]]
spinal tumors. Such intended uses encompass both degenerative
spondylolisthesis and spinal trauma. In addition, FDA is proposing to
classify the preamendments pedicle screw spinal system intended for the
treatment of severe spondylolisthesis into class II, in accordance with
section 513(d) of the act and 21 CFR 860.84.
FDA is proposing to place the pedicle screw spinal system in class
II because it believes that there is sufficient information to
establish special controls to provide reasonable assurance of its
safety and effectiveness.
Two categories of spinal fixation implants that were in commercial
distribution prior to the date of enactment of the amendments have been
classified into class II: Posterior hook-rod fixation devices
(classification: 21 CFR 888.3050, Spinal interlaminal fixation
orthosis) and anterior plate-screw-cable fixation devices
(classification: 21 CFR 888.3060, Spinal intervertebral body fixation
orthosis). In addition, bone plates and screws were placed into class
II when intended for general orthopedic use in long bone fracture
fixation (classifications: 21 CFR 888.3030, Single/multiple component
metallic bone fixation appliances and accessories). However, bone
plates and screws were considered postamendments class III devices when
incorporated into pedicle screw spinal systems. This proposal does not
affect the classification of those devices.
Pedicle screw spinal systems include a broad category of multiple
component implants. The first premarket notification submission
(510(k)) for a multiple component device system intended for attachment
to the spine via the pedicles of the vertebrae was submitted to FDA for
marketing clearance in 1984. FDA determined that the device was not
substantially equivalent to the following devices: (1) Single/multiple
component metallic bone fixation appliances and accessories intended
for long bone fracture fixation; and (2) interlaminal spinal fixation
device systems that attached to the spine via sublaminar wiring or
interlaminal hooks. FDA's decision was based on the fact that the
sponsor had not established that there was a preamendments device
incorporating pedicle screw components and that the device posed
potential risks not exhibited by other spinal fixation systems, such as
a greater chance of neurological deficit due to imprecise screw
placement or the event of a screw failure; pedicle fracture during
placement of screws; soft tissue damage or inadequate fusion due to
bending or fracture of device components; and greater risk of
pseudarthrosis due to instability of the device design. Because they
were not found to be substantially equivalent to a preamendments
device, these systems were automatically classified into class III
under section 513(f)(1) of the act.
In 1985, in response to another 510(k), FDA determined that the
interlaminal spinal fixation device (i.e., rods and hooks and/or
sublaminar wires) with screws attached to the sacrum was substantially
equivalent to the class II interlaminal spinal fixation device with
hooks supported on a rod threaded into the iliac crests (21 CFR
888.3050). However, when the same device was fixed to the pedicles, FDA
determined that the device was not substantially equivalent to the
spinal interlaminal fixation orthosis (21 CFR 888.3050) and is
therefore a postamendments class III device.
Clinical investigations of pedicle screw spinal systems under
investigational device exemption (IDE) protocols began in 1985. No
premarket approval application has been brought before the advisory
panel or approved to date.
By mid-1992, FDA discovered that the use of pedicle screw spinal
systems outside of approved IDE studies was widespread, and that
pedicle screw fixation was considered to be the standard of care by the
surgical community. To obtain guidance in resolving this issue in the
best interests of the public health, FDA convened an advisory panel
meeting on August 20, 1993, to review the available information
pertaining to the safety and effectiveness of the device. Mechanical
testing data, summaries of clinical studies conducted under FDA-
approved IDE protocols, and presentations by experts in the field were
presented to the Panel. After reviewing the information, the Panel
concluded that pedicle screw spinal devices appear to be safe and
effective when used as adjuncts to spinal fusion procedures, but that
additional clinical information was needed in order to determine what
regulatory controls should be required to provide reasonable assurance
of their safety and effectiveness.
During a February 1993 meeting, FDA requested the orthopedic
professional societies and spinal implant manufacturers to submit to
FDA all available valid scientific data on the performance of pedicle
screw spinal devices. In response, the Spinal Implant Manufacturers
Group (SIMG) was formed to provide the financing for a nationwide study
of the pedicle screw device. The SIMG consists of representatives from
the American Academy of Orthopedic Surgeons, the Scoliosis Research
Society, the North American Spine Society, the American Association of
Neurological Surgeons, the Congress of Neurological Surgeons, and 25
manufacturers of spinal implant systems. The Scientific Committee of
the SIMG, consisting of surgeons and scientists, was formed
specifically to develop and implement a uniform research protocol to
gather clinical experience from the use of the device. FDA also
provided extensive input into the design of the study protocol. With
the permission of individual IDE sponsors, FDA's scientific staff
provided the Scientific Committee with information about current IDE
clinical investigations, the types of diagnostic groups being studied,
the patient inclusion and exclusion criteria utilized, the outcome
variables under study, and insight into the types of problems
encountered with these studies. FDA also made recommendations regarding
the feasibility of various study designs, including an historical
cohort model. Finally, FDA provided the Scientific Committee with
extensive advice regarding statistical analysis of the data, validation
of data, reduction of study bias, and sample size calculations. The
Scientific Committee then conducted a nationwide historical cohort
study according to this research protocol.
The Panel met on August 20, 1993, and July 22, 1994, in open public
meetings to discuss the postamendments pedicle screw spinal system. At
the July 22, 1994, meeting, new information was presented to the Panel
by FDA and others, and recommendations were solicited from the Panel
regarding the classification of pedicle screw spinal systems. During
this meeting, the Panel heard testimony from FDA, the medical and
scientific communities, manufacturers, and the public regarding the
safety and effectiveness of the device. At this meeting, the SIMG
presented clinical data from its nationwide ``Historical Cohort Study
of Pedicle Screw Fixation in Thoracic, Lumbar, and Sacral Spinal
Fusions'' (Cohort study). FDA presented a comprehensive review of the
medical literature, an analysis of the Cohort study conducted by the
SIMG, and a summary of the clinical data that had been released by IDE
sponsors. Presentations of two meta-analyses of the literature
pertaining to the clinical performance of the device were given by
spinal surgeons. In addition, 38 persons gave presentations during the
public comment portion of the panel meeting. Patients who had had
spinal fusion
[[Page 51948]]
surgery with pedicle screw instrumentation gave personal testimonies of
their experiences with the device, citing both successes and failures.
Several litigation attorneys, representing patients involved in class
action lawsuits against spinal implant manufacturers, addressed the
Panel with their views. Five spine surgeons gave their professional
opinions regarding the usefulness of the pedicle screw device in their
practices. Three surgeons representing spinal professional societies
presented their societies' viewpoints.
At the conclusion of the July 22, 1994, meeting, the Panel
recommended that FDA reclassify the generic type of device from class
III into class II when intended for the treatment of degenerative
spondylolisthesis and spinal trauma. The Panel recommended further that
FDA adopt special controls as deemed necessary by FDA under
513(a)(1)(B) of the act, and that FDA assign a low priority for the
establishment of a performance standard for this generic type of device
under section 514 of the act (21 U.S.C. 360d).
Since 1986, a number of manufacturers have sought to demonstrate
that the pedicle screw spinal system is a preamendments device, that
is, that it was commercially available prior to May 28, 1976, the
enactment date of the 1976 amendments. In a 510(k) dated December 22,
1994, Sofamor Danek, Inc., provided sufficient evidence of the
preamendments commercial distribution of a spinal system that utilized
pedicle screws. In a letter to Sofamor Danek, Inc., dated January 20,
1995, FDA acknowledged that sufficient evidence now exists documenting
that pedicle screw spinal systems were commercially available prior to
May 28, 1976. The preamendments pedicle screw spinal fixation device
system consisted of hooks, spinal rods, threaded sacral rods, and
pedicle screws connected to the rods with wire. The device was intended
only for lumbar and sacral spine fusions using autogenous bone graft in
patients with severe spondylolisthesis (grades 3 and 4) with removal of
the device after spinal fusion was achieved. On January 20, 1995, the
first postamendments pedicle screw spinal system was found to be
substantially equivalent to the preamendments device. Based on this new
information, FDA has determined that the pedicle screw spinal system is
an unclassified preamendments device when indicated for autogenous bone
graft fusions of the fifth lumbar vertebra to the sacrum in patients
with severe spondylolisthesis (grades 3 and 4) at L5-S1 with
removal of the device after fusion has been achieved. In a letter,
dated April 3, 1995, FDA asked the Panel to provide its recommendations
on the classification of this preamendments device. The Panel
unanimously recommended that the preamendments pedicle screw spinal
system be classified into class II when intended for autogenous bone
graft fusions of the fifth lumbar vertebra to the sacrum in patients
with severe spondylolisthesis (grades 3 and 4) at L5-S1 with
removal of the device after fusion has been achieved.
In this document, FDA is publishing the recommendations of the
Panel with respect to classification of the preamendments device and
reclassification of the postamendments device. FDA is also proposing to
classify both the preamendments and postamendments devices into class
II, and to codify them in one regulation.
III. Recommendations of the Orthopedic and Rehabilitation Devices
Palen
The Orthopedic and Rehabilitation Devices Panel, an FDA advisory
panel, made the following recommendations regarding the classification
of the pedicle screw spinal system:
(1) Identification. A pedicle screw spinal system is a multiple
component device, made of alloys such as 316L stainless steel (Ref.
11), 316LVM stainless steel (Ref. 11), 22Cr-13Ni-5Mn stainless steel
(Ref. 12), unalloyed titanium (Ref. 9), and Ti-6Al-4V (Ref. 10), that
allows the surgeon to build an implant system to fit the patient's
anatomical and physiological requirements. A spinal implant assembly
consists of anchors (e.g., bolts, hooks, and screws); interconnection
mechanisms incorporating nuts, screws, sleeves, or bolts; longitudinal
members (e.g., plates, rods, and plate/rod combinations); and
transverse connectors. The device is used primarily in the treatment of
acute and chronic instabilities and deformities, such as trauma, tumor,
or degenerative spondylolisthesis.
(2) Classification recommendation. Class II (special controls). The
Panel recommended that the establishment of a performance standard be
low priority.
(3) Summary of reasons for recommendation. The Orthopedic and
Rehabilitation Devices Panel recommended that pedicle screw spinal
systems be classified into class II because the Panel believed that
general controls by themselves are insufficient to provide reasonable
assurance of the safety and effectiveness of the device, but that there
is sufficient information to establish special controls to provide such
assurance. The Panel also believed that premarket approval is not
necessary to provide reasonable assurance of the safety and
effectiveness of the device. The Panel believed that public information
demonstrates that the risks to health have been characterized and can
be controlled. The Panel also believed that the relationship between
these risks and the device's performance parameters have been
established and are sufficiently understood to assure the safety and
effectiveness of the device. Furthermore, the Panel recognized that
there exist voluntary standards and test methods with respect to the
production of the device.
(4) Summary of data on which the recommendation is based. The
Orthopedics and Rehabilitation Devices Panel based its recommendation
on the Panel members' personal knowledge of, and clinical experience
with, the device and presentations at the open panel meeting. The Panel
noted that, based upon clinical data from the Cohort study, IDE
clinical investigations, and the literature, pedicle screw spinal
systems performed at least equivalent to, and in some instances
superior to, currently available class II anterior and posterior spinal
fixation devices, as well as to treatments not utilizing internal
fixation devices for degenerative spondylolisthesis and trauma.
The Panel noted that, based on the Cohort study, clinical
investigations under IDE protocols and studies available from the
scientific literature, the use of pedicle screw spinal systems, when
intended for the treatment of degenerative spondylolisthesis and spinal
trauma, produced statistically significantly higher spinal fusion rates
than when no fixation or nonpedicle screw spinal fixation was used. In
addition, the Panel believed that these studies demonstrated
statistically significant improvements in patients' clinical outcomes
in terms of pain, function, and neurologic status. The Panel believed
that these studies demonstrated significant technical and clinical
advantages from the use of the device (Ref. 66).
According to the Panel, the mechanical testing data presented at
the August 20, 1993, panel meeting demonstrated that pedicle screw
spinal systems exhibit adequate mechanical strength, rigidity, and
fatigue resistance for the expected length of time required to
stabilize the spine to allow fusion to occur (Ref. 65).
The Panel concluded that the data presented at the July 22, 1994,
panel meeting provided clinical evidence that the device was effective
in stabilizing
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the spine in spinal fusions for degenerative spondylolisthesis and
spinal trauma. The Panel also determined that the incidence rates of
device breakage, deformation, and loosening were similar to those of
commercially available device systems and that the rates were
clinically acceptable. The types of device-related complications for
pedicle screw spinal systems reported to FDA under the MedWatch device
reporting program were comparable to those reported in clinical studies
and the medical literature for commercially available spinal systems
and included broken screws, neurologic injuries, and nonunions (Ref.
66).
The Panel did not find support in the literature or in clinical
data for use of the device in the treatment of low back pain. The Panel
specifically recommended that low back pain should not be included in
the indications for use of the device until clinical data justify its
inclusion (Ref. 66).
The Panel believed that the primary risks to health associated with
pedicle screw spinal systems are similar to those associated with other
class II spinal implant devices. The Panel believed that both clinical
and nonclinical parameters need to be controlled to provide reasonable
assurance of the safety and effectiveness of the device. The primary
nonclinical parameters affecting safety and effectiveness are: (1)
Biocompatibility of the materials used in the manufacture of the
device; (2) device design; (3) device durability; (4) device strength,
and (5) device rigidity. The primary measures of clinical effectiveness
of the device are: (1) Fusion, (2) pain relief, (3) functional
improvement, and (4) neurologic status. These concerns are the same as
those associated with commercially available class II devices,
including posteriorly placed interlaminal spinal fixation orthoses (21
CFR 888.3050) and anteriorly placed spinal intervertebral body fixation
orthoses (21 CFR 888.3060).
The Panel reviewed the medical literature pertaining to the use of
pedicle screw spinal systems in the treatment of severe
spondylolisthesis (Refs. 5, 6, 14, 27, 28, 29, 30, 48, 52, 68, 81, 82,
83, 84, 92, 93, 147, 155, 159, 168, 169, 175, and 188) and determined
that the risks associated with the device are no different than those
associated with the use of the preamendments class II spinal fixation
devices or those associated with pedicle screw spinal systems intended
for the treatment of other acute or chronic instabilities and
deformities. The Panel concluded that the effectiveness of the device
is related to its mechanical strength and rigidity, which have been
demonstrated to be superior to existing class II devices.
(5) Risks to health. The following risks are associated with the
pedicle screw spinal system: (a) Mechanical failure. The screw may bend
or fracture, loosen or pull-out, the plate or rod may bend or fracture,
the connector may slip resulting in loss of fixation and loss of
reduction; (b) soft tissue injury. The risks of tissue injury include
screw over-penetration of the vertebral body with associated injury to
major blood vessels or viscera; pedicle fracture; nerve root injury;
spinal cord injury; cauda equina injury; dural tear or cerebrospinal
fluid leak; blood vessel injury; and bowel injury; (c) pseudarthrosis.
The risk of nonunion, or pseudarthrosis, signifies failure of bony
fusion and persistent instability; and (d) need for reoperation. The
risk of a possible reoperation includes reoperation for infection or
bleeding; revision surgery; removal of device components for device
failure, or symptomatic, painful, or prominent hardware; and
reoperations for other reasons not related to fusion, such as nerve
root decompression. In addition, there are theoretical risks, such as
device-related osteoporosis, metal allergy, particulate debris, and
metal toxicity, for which no reliable human data exist.
A. Safety and Effectiveness: Nonclinical
1. Biocompatibility of Materials
The biocompatibility of stainless steel and titanium metal alloys
used in the fabrication of pedicle screw spinal systems has been
investigated extensively with in vitro testing, implantation studies,
mechanical testing, toxicological testing, corrosion testing, and
clinical trials. These alloys have been demonstrated to be reasonably
safe for human usage under a variety of conditions. (Refs. 23, 33, 67,
105, 111, 134, 135, 179, 180, 182, and 197).
Stainless steels, such as 316 L, 316 LVM, and 22Cr-13Ni-5Mn alloys,
are susceptible to some degree of crevice, pitting, and stress
corrosion. The presence of corrosion products can produce a localized
chronic inflammatory response with granuloma formation, macrophage
engorgement with particulate matter, and focal areas of necrosis (Refs.
41, 67, 76, 111, 167, 179, and 197). Metallic ion species from leaching
or corrosion can produce allergic responses (Refs. 61, 67, 120, and
148). These are recognized and well-described tissue reactions to
stainless steel implants and metal ions. Nevertheless, stainless steels
have been used extensively with great clinical success for the
fabrication of surgical implants, including bone plates, bone screws,
and intramedullary rods. The biocompatibility of stainless steels has
been regarded as acceptable for implants at various anatomic locations
under different pathophysiologic conditions (Refs. 38, 67, 105, 134,
135, 157, 158, 165, 179, and 181).
The corrosion resistance of commercially pure (CP) titanium and Ti-
6Al-4V alloy has been well-documented through in vitro testing,
implantation studies, toxicological testing, corrosion testing, and
clinical trials. Titanium and its alloys are susceptible to wear as
well as corrosion, and thus may cause black discoloration of
surrounding tissues and induce aseptic local fibrosis (Refs. 33, 42,
115, 121, 129, 139, 197, and 198). In the soft tissue surrounding
titanium alloy orthopedic implants, T-lymphocytes in association with
macrophages have been observed, implying an immunological response to
the debris (Ref. 103). Macrophage release of bone-resorbing mediators
in association with titanium wear debris has also been demonstrated
(Ref. 85). The significance of these observations regarding the
biologic and toxicologic effects of titanium ions and wear particles in
spinal fusion is uncertain since these tissue reactions have been
observed only in closed joint systems, such as hip replacements (Refs.
121 and 129). Despite these tissue responses, CP titanium and titanium
alloys are still considered relatively safe biomaterials, and may be
effectively used with minimal risk when not used as the articulating
surface, which leads to the generation of large amounts of wear debris
(Refs. 42, 121, 129, 139, 196, 197, and 198). Titanium and its alloys
have been used extensively as implant materials since the mid-1960's
for the fabrication of implants such as bone plates, bone screws, and
hip implants (Refs. 105, 129, 182, 196, 197, and 198).
All available metallic implant materials are imperfect
biomaterials. In the trade-off between the theoretical risks arising
from metal ion release, corrosion products, and wear debris, and the
known benefits of these materials, it appears that both stainless steel
and titanium alloys are acceptable for human implantation in the spinal
environment.
The Panel believed that the biocompatibility specifications of
existing voluntary standards provide reasonable assurance of the safety
and effectiveness of devices manufactured of
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metals and metallic alloys (Refs. 65 and 66).
2. Mechanical Properties of the Device
It has been demonstrated that the multiple component pedicle screw
spinal systems perform as well as other commercially available spinal
fixation device systems in various modes and frequencies of loading
(Refs. 8, 21, 45, 63, 67, 71, 73, 77, 98, 99, 100, 136, 137, 138, 142,
143, 144, 146, and 184).
Sufficient test methods exist to enable the evaluation of fatigue
strengths and tensile, torsional, and bending strengths of the pedicle
screw spinal fixation systems to assure its safety and effectiveness
during the period of time needed for fusion to occur (Refs. 8, 13, 21,
45, 66, 72, and 78). There is adequate mechanical testing data for the
pedicle screw spinal system for which clinical data was presented at
the July 22, 1994, panel meeting. For example, one of the pedicle
screw-plate systems had a static bending strength of 807.8 N, stiffness
of 123.7 KN/M, and flexibility of 8.18 x 10-3 M/KN (Ref. 45). In
cyclic fatigue testing, the same system endured 10 6 cycles with a
400 N load, 10 6 cycles with a 500 N load, and 212,960 cycles with
a 600 N load (Ref. 45). Pedicle screw-rod systems have reported static
bending strengths ranging from 544.9 to 1,289 N, stiffnesses ranging
from 136.9 to 153.2 KN/M, and flexibilities ranging from 6.53 to 7.32
( x 10-3) M/KN (Ref. 45). In cyclic fatigue testing, the pedicle
screw-rod fixation device systems have endured 10 6 cycles with a
400 N load, 202,769 to 10 6 cycles with a 500 N load, and 135,017
to 799,544 cycles with a 600 N load (Ref. 45).
B. Safety and Effectiveness: Clinical
The Panel based its recommendations on valid scientific evidence
from the Cohort study, IDE clinical investigations, and the medical
literature. These data sources allowed the Panel to evaluate the safety
and effectiveness of pedicle screw spinal systems in terms of
mechanical failure, soft tissue injury, pseudarthrosis, reoperation,
fusion, pain, function, and neurologic status, as well as other
potential harmful and beneficial effects of these devices.
Representatives of the SIMG presented the results of the Cohort
study at the July 22, 1994, panel meeting. The Cohort study was an
open, nonblinded, historical cohort study (Ref. 201). It was designed
to recruit a maximum number of surgeons who would voluntarily
participate by collecting clinical data on patients who had undergone
spinal fusions. Physicians were recruited through announcements at
professional society meetings and direct mailings to professional
society memberships. Clinical data were collected from medical records
of patients who had undergone spinal fusions during the period January
1, 1990, to December 31, 1991. This window was chosen to allow an
adequate number of patients with a theoretical minimum followup of 2
years up to the time of the study onset. The concurrent control groups
consisted of patients with identical entry criteria who had been
operated on during the same time window (1/1/90-12/31/91). These
control patients were either fused without instrumentation
(noninstrumented) or were fused and instrumented with a control device
(nonpedicle screw instrumentation). The data collection protocol was
identical to that used for the study group.
Three hundred fourteen surgeons voluntarily participated in this
study and contributed a total of 3,500 patients: 2,685 patients in the
Degenerative Spondylolisthesis group and 815 patients in the Fracture
(spinal trauma) group. In the Degenerative Spondylolisthesis group, the
2,685 patients were stratified by treatment: 2,177 patients were
treated with pedicle screw instrumented fusions, 51 patients with
nonpedicle screw instrumented fusion, and 457 patients with
noninstrumented fusion. Similarly, in the Fracture group, the 815
patients were stratified by treatment: 587 patients were treated with
pedicle screw instrumented fusions, 221 patients with nonpedicle screw
instrumented fusion, and 7 patients with noninstrumented fusion.
Data from three clinical evaluation periods were collected from
each patient record: Preoperatively, immediately postoperatively, and
at the final evaluation which ranged from six months to two years
postoperatively. The preoperative data included the patient's age,
gender, weight, primary diagnosis, involved levels, identification of
known prognostic variables (e.g., prior back surgery), and levels of
pain, function, and neurologic status. Information regarding the
operative procedure included the date of operation, type of bone
grafting (if any), the levels instrumented and fused, the name of the
pedicle screw device, and the number of each of the relevant components
(e.g., rods, screws, connectors). Data collected at the final
evaluation time point included the date of the last clinical and
radiographic evaluations; fusion status; the date fusion was first
diagnosed; maintenance of alignment; and neurologic, functional, and
pain assessments. Intraoperative and postoperative adverse events and
the incidence and cause of reoperations were recorded.
Ten prospective IDE clinical trials for multiple indications were
analyzed. Five studies involving the treatment of degenerative
spondylolisthesis (n = 268) and two studies involving the treatment of
spinal fracture (n = 27) were compared to the results of the Cohort
study and were presented to the Panel (Ref. 66).
A comprehensive search of the English-language medical literature
from 1984 to the present was performed. One hundred one articles
pertained to clinical performance of pedicle screw devices and were
selected for inclusion in this review (Ref. 66). Only articles
appearing in peer-reviewed journals were included. Meta-analyses of the
medical literature for degenerative spondylolisthesis and spinal trauma
were conducted and presented (Refs. 51, 66, and 119).
These data were analyzed and presented at the July 22, 1994, panel
meeting.
1. Mechanical Failure
The Cohort study provided the incidence of mechanical device
failures related to treatment with pedicle screw spinal systems,
nonpedicle screw instrumentation, and noninstrumented fusion (Refs. 66
and 201). For the fracture group (n = 586), the pedicle screw group had
a mechanical failure rate of 9.7 percent, compared to a 1.9 percent
failure rate in the nonpedicle screw group. For the pedicle screw
group, the incidence of screw fracture was 6.7 percent, screw loosening
2.1 percent, rod/plate fracture 0.3 percent, and connector loosening
(slippage) 0.2 percent. For the nonpedicle screw group (n = 221), the
incidence of rod/plate fracture was 0.9 percent, hook pull-out 0.5
percent, and connector slippage 0.5 percent
For the degenerative spondylolisthesis group, the device mechanical
failure rate was 7.8 percent in the pedicle screw group (n = 2,153).
The most frequent events for the pedicle screw group were screw
loosening (2.8 percent), screw fractures (2.6 percent), rod or plate
fractures (0.7 percent), and connector loosening (slippage) (0.7
percent). Mechanical device failures were not possible in the
noninstrumented group because a surgical technique, not an instrument
technique, was utilized.
The overall incidence of mechanical device failures in the IDE
clinical investigations (n = 2,431) was 0.7 to 3.7 percent (mean = 1.2
percent) (Ref. 66). For all investigational pedicle screw
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spinal systems reported, the incidence of rod/plate fractures for
degenerative spondylolisthesis was 0.0 to 7.1 percent (mean = 1.5
percent), for fractures 0.0 percent, for degenerative disc disease 0.0
to 4.0 percent (mean = 1.1 percent), for scoliosis 0.0 to 9.1 percent
(mean = 0.9 percent), for failed back syndrome 0.0 to 2.7 percent (mean
= 0.3 percent), and for spinal stenosis 0.0 to 7.7 percent (mean = 5.0
percent) (Ref. 66). The incidence of screw fractures for degenerative
spondylolisthesis was 0.0 to 18.6 percent (mean = 6.2 percent), for
fractures 20.0 to 28.6 percent (mean = 22.2 percent), for degenerative
disc disease 0.0 to 2.7 percent (mean = 0.6 percent), for scoliosis 1.8
percent, for failed back syndrome 0.0 to 3.4 percent (mean = 2.4
percent), and for spinal stenosis 0.0 to 14.3 percent (mean = 3.0
percent). The incidence of screw loosening or pull-out for degenerative
spondylolisthesis was 0.0 to 9.3 percent (mean = 0.9 percent), for
fractures 0.0 to 5.0 percent (mean = 3.7 percent), for degenerative
disc disease 0.0 to 7.4 percent (mean = 0.7 percent), for scoliosis 0.0
to 3.5 percent (mean = 1.8 percent), for failed back syndrome 0.0 to
12.1 percent (mean = 1.6 percent), and for spinal stenosis 0.0 percent.
The incidence of connector loosening was 0.0 percent for degenerative
spondylolisthesis, fractures, scoliosis, and spinal stenosis, 0.0 to
2.1 percent (mean = 0.4 percent) for degenerative disc disease, and 0.1
percent for failed back syndrome.
A low rate of mechanical failure of pedicle screw fixation devices,
when used in multiple indications, is further documented by the medical
literature (Refs. 3, 5, 19, 22, 24, 32, 35, 37, 43, 47, 50, 58, 59, 60,
73, 77, 79, 87, 89, 90, 94, 95, 107, 109, 110, 113, 116, 122, 125, 150,
151, 152, 162, 163, 164, 173, 183, 185, 186, 187, 191, 192, 193, and
203). A meta-analysis of 58 clinical studies revealed no differences
between pedicle screw fixation (n = 641), hook-rod fixation (n = 1128),
anterior fixation (n = 255), and sublaminar wire-rod fixation (n = 48)
groups in the rate of mechanical device failures (Refs. 51 and 119).
Survivorship analysis of pedicle screw device failures (defined as
screw bending or breaking, infection, device loosening, rod or plate
hardware problems, or neurologic complication requiring device removal)
in patients treated for spondylolisthesis, postlaminectomy instability,
pseudarthrosis, trauma, scoliosis, and tumor demonstrated a 90 percent
survival of the instrumentation at 20 months, and 80 percent survival
at 5 to 10 years (Ref. 124). The cumulative survivorship at 1 year was
84.0 percent and 91.3 percent for two devices used in the treatment of
patients diagnosed with degenerative isthmic spondylolisthesis,
degenerative segmental instability, and degenerative lumbar scoliosis
(Ref. 26). Survivorship analysis performed on thoracolumbar burst
fractures treated with pedicle screw fixation also demonstrated high
survival rates for the implants: 100 percent at 22.4 months and 75
percent from 22.4 to 32 months (54).
2. Soft Tissue Injury
The incidence of device-related soft tissue injuries associated
with the use of pedicle screw spinal systems for both degenerative
spondylolisthesis and fracture groups is comparable to that associated
with nonpedicle screw instrumented fusions and noninstrumented fusions
(Refs. 66 and 201). Clinical studies have documented 0.1 percent and
0.2 percent rates of vascular injuries related to the use of pedicle
screw spinal systems for the degenerative spondylolisthesis and
fracture groups, respectively, and no visceral (intestinal) injuries
for those groups. There were no differences found between treatment
groups for intraoperative and postoperative neurological injuries,
including nerve root and spinal cord injuries, as well as new radicular
pain. For the degenerative spondylolisthesis and fracture groups,
intraoperative nerve root injuries occurred in 0.4 percent and 0.2
percent of cases, respectively; intraoperative spinal cord injuries
occurred in 0.1 percent and 0.2 percent of cases, respectively;
postoperative radicular pain or deficits in 4.8 percent and 0.9 percent
of cases, respectively; intraoperative device-related dural tears in
0.1 percent and 0.7 percent of cases, respectively; and postoperative
dural tears or leaks in 0.3 percent and 0.0 percent of cases,
respectively (Refs. 66 and 201).
The data released from the IDE clinical investigations reported an
overall vascular injury rate of 0.7 percent; an intraoperative nerve
root injury rate of 0.1 percent; a wound infection rate of 3.7 percent;
a postoperative radicular pain or deficit rate of 2.2 percent; and a
rate of postoperative dural tears or leaks of 0.8 percent. In these
investigations, intraoperative spinal cord injuries did not occur (Ref.
66).
The medical literature documents a low incidence of soft tissue
injuries related directly to the device when used in the treatment of
fractures (Refs. 46, 49, 74, 106, 127, and 153), degenerative
spondylolisthesis (Refs. 26, 27, 37, 49, 60, 113, 183, 185, 187, 191,
and 192), isthmic spondylolisthesis (Ref. 147), degenerative disc
disease (Refs. 47, 60, 113, 183, 187, 191, and 192), deformities (Ref.
25), scoliosis (Refs. 43 and 116), tumors (Ref. 126), spinal stenosis
(Ref. 173), and multiple diagnoses (Refs. 112 and 122). A meta-analysis
of the medical literature for treatment of degenerative
spondylolisthesis and fracture demonstrates no differences in the rates
of intraoperative and postoperative adverse events related to soft
tissue injuries among pedicle screw fixation, hook-rod fixation,
anterior fixation, and sublaminar wire-rod fixation treatment groups (p
< 0.05) (Refs. 51 and 119).
These soft tissue injuries appear to be related to the surgical
procedure, rather than the device itself. Misdirected pedicle screws
can cause pedicle fracture, screw cutout, or screw penetration of the
pedicle, potentially causing nerve root or spinal cord injuries, dural
tears, or canal stenosis (Refs. 152, 166, 171, and 189). Meticulous
surgical technique and attention to detail appear to minimize these
adverse events (Refs. 24, 47, 60, 79, 90, and 190). Pedicle screws too
large for the pedicle diameter can cause pedicle fracture. Likewise,
over penetration of pedicle screws through the vertebral body from
pedicle screws too long for the anterior-posterior dimensions of the
vertebrae can cause retroperitoneal vascular or visceral injury (Refs.
101, 106, and 204). Thus, selection of the appropriate size of the
pedicle screw is critical to prevent these injuries (Refs. 64 and 190).
Operative technique guidelines have been developed to assure accurate
placement of pedicle screws and minimize operative complications (Refs.
16, 56, 149, 164, and 172). In addition, the relevant surgical anatomy
of the thoracic, lumbar, and sacral spine, including the pedicle
dimensions and orientation, as well as surrounding soft tissue
structures, have been thoroughly described in the medical literature
(Refs. 7, 15, 20, 57, 62, 64, 69, 75, 87, 88, 91, 101, 102, 106, 117,
131, 132, 133, 141, 145, 156, 161, 166, 171, 176, 177, 189, 190, 195,
199, and 204).
3. Pseudarthrosis
In the Cohort study, radiographic data were available to determine
the fusion status for 1,794 patients in the pedicle screw group and 382
patients in the noninstrumented group for the treatment of degenerative
spondylolisthesis, and 506 patients in the pedicle screw group and 184
patients in the nonpedicle screw group for the treatment of fracture.
There was a statistically significant reduction in
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the incidence of pseudarthrosis in the degenerative spondylolisthesis
group when treated with pedicle screw fixation (3.7 percent) compared
to treatment without instrumentation (17.0 percent) (p < 0.001).
However, there was no significant difference in the incidence of
pseudarthrosis associated with the use of pedicle screw fixation in
treating fractures (1.8 percent) compared to treatment with nonpedicle
screw fixation devices (3.3 percent) (p = 0.18) (Refs. 66 and 201).
In the data released from the IDE clinical investigations, the
incidence of pseudarthrosis for degenerative spondylolisthesis was 0.0
to 44.0 percent (mean = 12.6 percent), for fractures 10.0 to 14.3
percent (mean = 11.1 percent), for degenerative disc disease 0.0 to
37.0 percent (mean = 8.4 percent), for scoliosis 0.0 to 36.4 percent
(mean = 3.7 percent), for ``failed back syndrome'' 0.0 to 47.2 percent
(mean = 12.6 percent), and for spinal stenosis 5.1 to 14.3 percent
(mean = 13.0 percent) (Ref. 66).
The medical literature similarly documents a low incidence of
pseudarthrosis in those treated with pedicle screw spinal systems for
fractures (Refs. 3, 17, 34, 35, 36, 47, 80, 153, and 154), degenerative
spondylolisthesis (Refs. 32, 37, 96, 125, 173, and 174), deformities
(Ref. 25), degenerative spondylosis (Refs. 22, 24, 169, and 194),
degenerative disc disease (Ref. 205), and tumor (Refs. 50 and 126).
Survivorship analysis for pseudarthrosis demonstrated a 98 percent
fusion rate at one year, 97 percent at 12 to 20 months, 96 percent at
21 to 30 months, and 93 percent at 31 to 40 months (Ref. 124).
4. Reoperation
Reoperations were necessary in 17.6 percent and 23.2 percent of
cases, respectively, for the degenerative spondylolisthesis and
fracture groups in the Cohort study (Refs. 66 and 201). Device removals
constituted the vast majority of reoperation procedures: 270 of 379
(71.2 percent) patients with reoperations in the degenerative
spondylolisthesis group, and 109 of 136 (80.1 percent) patients with
reoperations in the fracture group. Most device removals were performed
for pain, irritation, or prominence of the device (6.3 percent and 7.2
percent in the degenerative spondylolisthesis and fracture groups,
respectively). Only a small percentage of the devices were removed for
device failure (0.6 percent and 1.5 percent in the degenerative
spondylolisthesis and fracture groups, respectively).
In the data released from the IDE clinical investigations, the
rates of reoperations reported for degenerative spondylolisthesis were
1.4 to 13.2 percent (mean = 5.0 percent), for fractures 10.0 to 14.3
percent (mean = 11.1 percent), for degenerative disc disease 1.4 to
10.5 percent (mean = 2.3 percent), for scoliosis 2.3 percent, for
failed back syndrome 1.1 to 8.8 percent (mean = 1.6 percent), and for
spinal stenosis 5.1 to 5.6 percent (mean = 5.0 percent) (Ref. 66). The
medical literature documents rates of device-related and nondevice
related reoperations of 7.0 percent to 24 percent for pedicle screw
fixation cases for a variety of conditions (Refs. 50, 60, 86, and 173).
Meta-analysis of the literature demonstrated that the reoperation rate
for the treatment of fractures with pedicle screw spinal systems (5.8
percent) are comparable to the reoperation rates associated with hook-
rod devices (8.9 percent) and anterior devices (2.7 percent) (Refs. 51
and 119).
5. Fusion
Comparing the degenerative spondylolisthesis and fracture groups in
the Cohort study, patients treated with pedicle screw fixation had a
significantly higher fusion rate (89.1 percent and 88.5 percent,
respectively) than the nonpedicle (70.8 percent and 81.0 percent) and
noninstrumented (70.4 percent and 50.5 percent) groups (p < 0.0001).
Using actuarial analysis, the time-adjusted rates of fusion for the
degenerative spondylolisthesis group demonstrated that treatment with
pedicle screw fixation was associated with a significantly greater rate
of fusion than treatment with no instrumentation (82.5 percent versus
74.5 percent, p < 0.001). The time-adjusted rates of fusion for the
fracture patient group demonstrated that there was no significant
difference in the rates of fusion when comparing pedicle screw fixation
and nonpedicle screw fixation. For the degenerative spondylolisthesis
group, the rate of fusion was higher in those treated with pedicle
screw fixation than in those treated without instrumentation at every
time interval beyond 3 months. These rates are evidence that fusion
occurs faster in the pedicle group (Refs. 66 and 201).
In the data released from clinical investigations performed under
IDE's, fusion rates associated with pedicle screw spinal systems were
comparable to those associated with nonpedicle screw instrumentation
and noninstrumentation. The fusion rates in patients with pedicle screw
fixation were 82.1 to 89.5 percent (mean = 87.8 percent) in the
treatment of degenerative spondylolisthesis, 71.4 to 80.0 percent (mean
= 77.8 percent) for fractures, 82.9 to 93.1 percent (mean = 85.9
percent) for degenerative disc disease, 96.5 percent for scoliosis,
88.6 to 94.7 percent (mean = 91.9 percent) for ``failed back
syndrome,'' and 85.7 to 92.3 percent (mean = 91.3 percent) for spinal
stenosis (Ref. 66).
A high incidence of successful fusion after pedicle screw fixation
is documented in the medical literature. The fusion rates for the
treatment of spinal deformity was 100 percent (Ref. 86); for low back
syndrome 100 percent (Ref. 109); for postlaminectomy instability 94
percent (Ref. 113); for fracture 88.5 percent to 100 percent (Refs. 55,
66, 80, and 201); for postsurgical failed back syndrome 91.6 percent
(Ref. 173); for pseudarthrosis 80 percent to 94 percent (Refs. 113 and
186); for degenerative spondylosis 87 percent to 100 percent (Refs. 22,
169, 185, and 187); for spinal stenosis 96 percent to 100 percent
(Refs. 113, 163, and 173); for scoliosis 100 percent (Ref. 163); for
spondylolisthesis 78 percent to 100 percent (Refs. 27, 37, 49, 96, 113,
125, and 173); and for multiple diagnoses 77 percent to 100 percent
(Refs. 49, 95, 110, 183, 192, 200, and 202). A randomized prospective
trial comparing pedicle screw fixation with noninstrumented fusion
demonstrated a significant improvement in the rate of successful fusion
when pedicle fixation was utilized (94 percent fusion rate with rigid
pedicle screw instrumentation versus 65 percent without
instrumentation) (Ref. 202).
Meta-analyses of the medical literature compared the treatment
outcomes with pedicle screw fixation with three types of class II
spinal fixation systems, i.e., posterior hook-rod devices, anterior
instrumentation, and sublaminar wire-rod instrumentation. For
thoracolumbar spine fractures, patients treated with pedicle screw
fixation had a significantly higher rate of successful fusion (99.4
percent) than those treated with hook-rod fixation (96.9 percent) or
anterior fixation (94.8 percent), p < 0.05 (Ref. 51). There were no
significant differences in the fusion rates for patients with
degenerative spondylolisthesis treated with pedicle screw fixation (93
percent) and those treated with hook-rod/sublaminar wire-rod fixation
(96 percent) or anterior fixation (94 percent) (Ref. 119).
6. Pain
For the degenerative spondylolisthesis patients in the Cohort
study, the rate of improvement in back pain was significantly greater
in the pedicle group (91.5 percent) when compared to the
noninstrumented group (84.0 percent), p < 0.001. In contrast, the
[[Page 51953]]
rate of back pain improvement was greater in the nonpedicle group (95.2
percent) than the pedicle group (90.1 percent) for the fracture patient
group, p < 0.023. The rate of improvement in leg pain was significantly
greater in those degenerative spondylolisthesis patients treated with
pedicle screw fixation (91.5 percent) than those treated without
instrumentation (88.2 percent), p < 0.027. There were comparable
improvements in pain in patients treated with pedicle screw fixation
(90.1 percent) and nonpedicle screw instrumented fusion (95.2 percent)
for the fracture patient group (Refs. 66 and 201).
Clinical investigations performed under IDE protocols have
demonstrated rates of improvement in pain ranging from 79.1 to 89.3
percent (mean = 85.7 percent) in the treatment of degenerative
spondylolisthesis, 70.0 to 85.0 percent (mean = 74.1 percent) for
fractures, 71.7 to 86.2 percent (mean = 78.2 percent) for degenerative
disc disease, 44.2 percent for scoliosis, 72.4 to 81.6 percent (mean =
76.8 percent) for failed back syndrome, and 71.4 to 84.6 percent (mean
= 82.6 percent) for spinal stenosis (Ref. 66).
The medical literature also documents successful outcomes for pain
in patients treated with pedicle screw fixation with success rates
ranging from 67 percent to 100 percent (Refs. 2, 19, 27, 37, 80, 86,
95, 97, 109, 110, and 147). A meta-analysis of these data showed that
the 83.3 percent rate of improvement in pain for patients treated with
pedicle screw instrumentation was comparable to the 83.3 percent rate
for hook-rod instrumentation and the 77.0 percent rate for anterior
instrumentation in the treatment of fractures (Ref. 51). Similarly, the
rate of satisfactory clinical (pain and function) outcomes in patients
treated for degenerative spondylolisthesis with pedicle screw
instrumentation was 85.7 percent, which was comparable to those treated
with nonpedicle screw instrumentation (89.6 percent) or noninstrumented
fusions (89.6 percent) (Refs. 51 and 119).
7. Function
In the Cohort study, data on functional status was available from
2,132 patients in the pedicle screw group and 451 patients in the
noninstrumented group for the treatment of degenerative
spondylolisthesis, and from 569 patients in the pedicle screw group and
211 patients in the nonpedicle screw group for the treatment of
fracture. In the degenerative spondylolisthesis group, there was a
significantly greater incidence of functional improvement associated
with the use of pedicle screw fixation (90.4 percent) compared to
treatment without instrumentation (86.7 percent) (p < 0.02). In
contrast, in the fracture group, there was a significantly lower
incidence of functional improvement associated with the use of pedicle
screw fixation (87.9 percent) compared to treatment with nonpedicle
screw fixation (93.4 percent) (p < 0.027) (Refs. 66 and 201).
In the IDE clinical investigations, the rate of functional status
improvement for degenerative spondylolisthesis treated with pedicle
screw instrumentation was 79.1 to 86.8 percent (mean = 84.4 percent),
fractures 75.0 to 85.7 percent (mean = 77.8 percent), degenerative disc
disease 74.1 to 75.7 percent (mean = 75.4 percent), scoliosis 34.9
percent, failed back syndrome 69.3 to 73.6 percent (mean = 71.6
percent) and spinal stenosis 71.4 to 74.4 percent (mean = 73.9 percent)
(Ref. 66).
In the medical literature, the rate of successful functional
outcomes in the treatment of spinal stenosis was 78 percent (Ref. 173);
isthmic spondylolisthesis 90.9 percent (Ref. 147); postsurgical failed
back syndrome 80.2 percent (Ref. 173); degenerative disc disease 60
percent (Ref. 206); and low back pain 72 percent (Ref. 109). A meta-
analysis of these data showed that the 82.0 percent rate of improvement
in functional outcomes of patients treated with pedicle screw
instrumentation was comparable to the 74.8 percent rate for hook-rod
instrumentation and the 73.2 percent rate for anterior instrumentation
in the treatment of fractures (Ref. 51).
8. Neurologic Status
In the Cohort study, in the degenerative spondylolisthesis group,
the rate of improvement of spinal cord neurologic function was
comparable for those treated with pedicle screw fixation (3.6 percent)
and those treated with noninstrumented fusion (1.2 percent). For the
fracture group, there were no significant differences in the rates of
improvement of spinal cord neurological assessments between the pedicle
screw (13.3 percent) and nonpedicle screw instrumentation (13.0
percent) groups (p < 0.91) (Refs. 66 and 201).
For the degenerative spondylolisthesis group, the rate of root
status improvement by one grade or more was significantly greater in
patients treated with pedicle screw fixation (36.8 percent) than in
patients treated without instrumentation (29.2 percent), or with
nonpedicle screw fixation (25.5 percent), p < 0.002. In the fracture
group, the rates of improvement in root neurological assessments were
comparable in the pedicle screw instrumented group (24.1 percent) and
the nonpedicle screw instrumented group (18.2 percent) (p < 0.08)
(Refs. 66 and 201).
In the IDE clinical investigations, there was improved neurological
root status in 11.8 to 32.6 percent of patients (mean = 19.3 percent)
with degenerative spondylolisthesis, in 7.5 to 30.7 percent of patients
(mean = 17.6 percent) with degenerative disc disease, in 12.2 to 32.2
percent of patients (mean = 20.5 percent) with failed back syndrome, in
5.8 percent of patients with scoliosis, in 28.6 percent of patients
with spinal stenosis, and in 14.3 percent of patients with fracture
(Ref. 66).
Improvement in the neurological status of patients treated with
pedicle screw fixation in the medical literature ranged from 18.8
percent to 100 percent, and was found to be comparable to that
resulting from nonpedicle screw instrumented fusions and
noninstrumented fusions (Refs. 39, 49, 55, 80, 107, 153, 154, and 164).
Meta-analysis of the literature for the treatment of thoracolumbar
fractures demonstrated a statistically higher rate of neurologic
improvement in the anterior instrumentation (51.4 percent) and hook-rod
instrumentation (40.7 percent) treatment groups compared to the pedicle
screw instrumentation group (24.3 percent) (p < 0.05). However, the
pedicle screw treatment group had a significantly greater proportion of
neurologically intact (Frankel E) preoperative neurological profiles
compared to all other treatment groups and, hence, no potential for
neurological recovery (Ref. 51). There were no significant differences
between treatment groups in the number of patients who were
neurologically worse or who had neurological complications (Ref. 51).
9. Potential Effects on Bone Density
Experimental work has demonstrated decreased pedicle screw fixation
strength in bone with decreased bone mineral density (Refs. 40 and
167), and care must be taken, therefore, in patients with osteoporosis
(Ref. 170). Animal studies have demonstrated significant device-related
decrease in bone density following arthrodesis with rigid spinal
instrumentation (Ref. 123). However, rates of successful fusion
increase with increased mechanical rigidity of the spinal fixation
systems used to stabilize the spine. The significance of these findings
in the clinical setting has not been resolved.
[[Page 51954]]
10. Potential Benefits of Pedicle Screw Spinal Systems
The number of motion segments in fracture patients that were
required to be fused when using pedicle screw fixation has been
reported to be half that required when using hook-rod and sublaminar
wire-rod instrumentation (Refs. 77, 109, 154, and 203). This reduction
in the number of spinal segments fused preserves motion at the adjacent
motion segments, particularly at the important caudal levels of the
spine. In these same publications, the authors reported that, when
using pedicle screw spinal systems, the frequency of disc degeneration
at levels adjacent to the fused segments was found to occur at rates
comparable to those occurring in hook-rod and sublaminar wire-rod
instrumentation systems.
The rigid, segmental, three-column fixation achieved with pedicle
screw fixation allowed successful fixation of severely unstable spines
in cases of tumor (Refs. 31, 77, 94, and 114), severe fracture-
dislocation (Refs. 2, 4, 17, 35, 46, 53, 58, 59, 73, 107, 108, 128,
130, 140, 153, 154, 160, and 178), deformities (Ref. 25),
pseudarthrosis (Ref. 104), severe spondylolisthesis (Refs. 27, 77, and
175), and instability following extensive laminectomy (Refs. 113 and
118). Two authors reported that posterior distraction achievable with
pedicle screw instrumentation may allow greater fracture reduction and
spinal canal decompression, and may improve neurological recovery
(Refs. 70 and 203).
IV. FDA's Tentative Findings
FDA agrees with the Orthopedic and Rehabilitation Devices Panel's
recommendation and is proposing that the pedicle screw spinal system
intended for the treatment of degenerative spondylolisthesis, severe
spondylolisthesis, and spinal trauma be classified into class II. FDA
believes that there exists sufficient information to develop special
controls which will provide reasonable assurance of the safety and
effectiveness of these devices. FDA believes that appropriate special
controls should include mechanical testing standards of performance,
special labeling requirements, and postmarket surveillance. FDA also
believes that premarket approval is not necessary to provide reasonable
assurance of the safety and effectiveness of the device.
The data demonstrate that the use of pedicle screw-based
instrumentation in the treatment of degenerative spondylolisthesis and
fractures results in significantly higher fusion rates, improved
clinical outcomes, and comparable complication rates when compared with
treatment with no instrumentation or with currently available
preamendments class II spinal devices (see section III.B. of this
document).
The data also demonstrate that the use of pedicle screw-based
instrumentation in the treatment of severe spondylolisthesis results in
equivalent or higher fusion rates, similar clinical outcomes, and
comparable complication rates when compared with treatment with no
instrumentation or with currently available preamendments class II
spinal devices (Refs. 5, 6, 14, 27, 28, 29, 30, 48, 52, 68, 81, 82, 83,
84, 92, 93, 147, 155, 159, 168, 169, 175, and 188).
V. Summary of Data Upon Which FDA's Findings are Based
A. Clinical and Mechanical Data
FDA analyzed the medical literature pertaining to pedicle screw
spinal systems and presented its findings at the July 22, 1994,
advisory panel meeting (Ref. 66). The literature pertaining to the
clinical performance of pedicle screw spinal systems is extensive and
describes clinical indications for use, descriptions of surgical
techniques, definitions of clinical endpoints and outcome variables
used to evaluate safety and effectiveness, and descriptions of the
types, and estimates of the frequencies, of device-related
complications. The literature pertaining to the mechanical
characteristics of pedicle screw-based spinal instrumentation is also
extensive and provides considerable data on the device materials,
strength, and other mechanical characteristics of the device (see
section II.A.2. of this document).
Review of publicly released IDE clinical investigation data from
annual reports (Ref. 65), as well as data released by the study
sponsors (Ref. 66), provided FDA clinical data from controlled
investigations on clinical and radiographic outcomes, fusion rates, and
device-related complication rates.
Review of the MedWatch and Medical Device Reporting (MDR) data
bases, FDA's device problem reporting systems, provided information
regarding the types of device-related complications associated with the
use of spinal instrumentation devices. The complications associated
with pedicle screw spinal systems reported to FDA were comparable to
those associated with the use of commercially available class II spinal
fixation devices (Ref. 66).
The Cohort study data, submitted to the agency by the Scientific
Committee and presented to the panel at the July 22, 1994, meeting,
provided data from a large cohort of patients with spinal fusions
(Refs. 66 and 201). FDA evaluated the Cohort study and identified a
number of shortcomings in the study design. FDA found that the Cohort
study design has weaknesses inherent in all retrospective studies,
including concerns of possible selection bias; comparability of the
treatment groups; differences in the diagnostic inclusion criteria;
treatment differences, including differences in surgeon skill and
experience, surgical procedures, devices, and postoperative care;
differences in outcome measurement and reporting; and the degree of
completeness of medical records (Ref. 66). In addition, FDA found that
a significant number of cases did not complete the 2-year followup
period required for IDE clinical trials and that several issues
regarding the pooling of data were not addressed (Ref. 66). However,
many of these weaknesses were anticipated in the planning phase of the
study and steps were taken to minimize these potential problems.
FDA has determined that, despite its weaknesses, the Cohort study
was conducted in a scientifically sound manner (Ref. 66). The
investigation provided adequate numbers of cases, followup times,
clinical performance data, and complication rate data to permit
assessment of the safety and effectiveness of the device. In addition,
FDA has determined that the data meet the criteria for valid scientific
evidence found in 21 CFR 860.7(c)(2), that is, they are from partially
controlled studies, studies and objective trials without matched
controls, well-documented case histories conducted by qualified
experts, and reports of significant human experience with a marketed
device, from which it can fairly and responsibly be concluded by
qualified experts that there is reasonable assurance of the safety and
effectiveness of a device under its conditions of use. Under this
regulation, the evidence may vary according to the characteristics of
the device, its conditions of use, the existence and adequacy of
warnings and other restrictions, and the extent of experience with its
use.
FDA recognizes that the design and intent of the Cohort study was
to investigate two demanding clinical situations rather than merely two
diagnostic groups. The investigation of this device for these two
diagnostic entities constituted a ``worst case scenario.'' FDA has
concluded that these entities represented the extremes
[[Page 51955]]
of acute and chronic instabilities and deformities. Therefore, FDA had
strongly recommended that the study design be limited to degenerative
spondylolisthesis and spinal fracture in order to produce a more
meaningful investigation (Ref. 66). These entities were well-recognized
and easily definable diagnoses with established radiographic findings,
clinical symptomatology, surgical indications, and treatment outcomes.
These two diagnoses were expected to yield homogeneous patient groups
in terms of recognized prognostic variables. More importantly, these
diagnostic groups were recognized to be mechanically demanding and
clinically challenging situations that would rigorously test the
device. The fracture group, which included fractures and fracture-
dislocations, represented the extreme of spinal instability, and was
often accompanied by neurologic deficit, deformity, pain, and severe
functional loss. The degenerative spondylolisthesis group represented
chronic instability with deformity from degenerative disease.
FDA believes that the following special controls, in combination
with the general controls applicable under the act, would provide
reasonable assurance of the safety and effectiveness of pedicle screw
spinal systems:
(1) Compliance with materials standards, such as ASTM F136, F138,
and F1314 (serve to control risks of implant breakage, particulate
debris, and metal toxicity); (2) Compliance with mechanical testing
standards, such as ASTM PS-5-94, (serves to control risks of implant
breakage, loss of fixation, loss of alignment, and loss of reduction);
(3) Compliance with biocompatibility testing standards, such as
``Tripartite Biocompatibility Guidance for Medical Devices'' (9/86) and
International Standards Organization (ISO) 10993-1 (serve to control
biocompatibility concerns, such as metal toxicity and long-term
theoretical risks of carcinogenicity); and (4) Compliance with special
labeling requirements (serve to control risks such as nerve root or
spinal cord injury, dural tears, vascular injury, visceral injury,
pedicle fracture, vertebral body penetration, pseudarthrosis, and loss
of fixation and alignment, by adequately warning physicians of
potential risks related to the use of the device). For example, the
following labeling would be required:
Warning: The safety and effectiveness of pedicle screw spinal
systems have not been determined for spinal conditions other than
those with significant mechanical instability or deformity requiring
fusion with instrumentation. These include significant mechanical
instability secondary to spondylolisthesis, vertebral fractures and
dislocations; scoliosis, kyphosis, spinal tumors, and pseudarthrosis
resulting from previously unsuccessful fusion attempts.
Warning: Implantation of pedicle screw spinal systems is a
technically demanding surgical procedure with a significant
potential risk of serious injury to patients. This procedure should
only be performed by surgeons with adequate training and experience
in both the specific surgical technique and use of the specific
products to be implanted.
(5) Conduction of postmarket surveillance (PMS) studies for pedicle
screw spine systems as a mechanism to address issues related to device
specific design differences, surgical techniques, and device usage.
Because complications most frequently occur intraoperatively or early
post-operatively, yet important common complications occur late post-
operatively, a potential PMS study design might include the first 1000
subjects evaluated for intraoperative and early complications and the
first 100 subjects evaluated for a minimum of 2 years for late
complications.
The agency invites comments on special controls, including labeling
statements, which are appropriate to mitigate the risks from use of
these devices as they are proposed to be reclassified.
B. Indications for Use
Spinal instability is defined in terms of real or potential neural
dysfunction as measured by the degree of structural damage to the
vertebral column. Instability has also been defined in terms of
fracture patterns or neurologic deficit (Refs. 17 and 58), or excessive
sagittal plane translation on flexion-extension radiographs or
spondylolisthesis (Ref. 19). Spinal deformities include structural
deformities, such as scoliosis, kyphosis, lordosis, and severe
spondylolisthesis.
Fusion of the thoracic, lumbar, and sacral spine is often necessary
in the treatment of disorders that involve instability and deformity.
Fusion provides permanent stabilization of the involved unstable motion
segments and correction of structural deformities, and prevents the
long-term sequelae of these disorders.
Clinically, all entities that require fusion, either to treat acute
or chronic instability or to correct a spinal deformity, may be
indications for the use of adjunctive spinal instrumentation. Spinal
instrumentation, including anterior instrumentation systems and
posterior hook-rod, sublaminar wire-rod, or pedicle screw-based
instrumentation systems, is used as an adjunct to fusion by
immobilizing and stabilizing the involved vertebral motion segments
until fusion occurs. Successful fusion is dependent on the maintenance
of spinal alignment and elimination of motion at the fusion site.
Spinal instrumentation systems are simply contrivances that promote
fusion by providing immobilization and stabilization between
intervertebral motion segments.
Mechanically, the stabilization of the involved motion segments and
maintenance of alignment are accomplished by all types of spinal
instrumentation systems by attaching anchors to vertical supporting
members (Ref. 13). The posterior hook-rod and posterior sublaminar
wire-rod device systems provide mechanical stabilization of the
vertebrae with longitudinal rods attached to the laminae or spinous
processes via hooks or wires. The anterior plate-screw-cable fixation
devices provide stabilization with longitudinal plates or cables
attached to the vertebral bodies via screws placed anteriorly or
laterally. Similarly, pedicle screw spinal systems provide
stabilization of vertebrae with longitudinal plates or rods attached to
the vertebral bodies via screws through the pedicles. Mechanical
testing has demonstrated that the pedicle screw spinal systems has
equivalent or superior mechanical characteristics, such as static and
fatigue strength, when compared to asti class II posterior hook-rod and
anterior plate-screw-cable spinal devices (see section III.A.2. of this
document). In addition, the rigidity of the vertebrae instrumented with
pedicle screw spinal systems is greater than when instrumented with the
other device systems (see section III.A.2. of this document). In vivo
studies have demonstrated that the strength of the fusion is directly
related to the rigidity of the spinal instrumentation (Ref. 123).
Clinical studies also have verified that the rate of successful fusion
is related to the rigidity of the spinal instrumentation (Ref. 202).
FDA believes that the indications for use of asti devices, as
described in 21 CFR 888.3050 and 888.3060, are comparable to the
proposed indications for pedicle screw spinal systems. Currently, the
class II asti posterior hook-rod, sublaminar wire-rod, sacral screw-
rod, and iliac screw-rod fixation devices, ``Spinal interlaminal
fixation orthoses,'' are used to ``straighten and immobilize the spine
to allow bone grafts to unite and fuse the vertebrae together'' (21 CFR
888.3050). The intended use is ``primarily in the treatment of
scoliosis (a lateral curvature of the spine), but it also may
[[Page 51956]]
be used in the treatment of fracture or dislocation of the spine,
grades 3 and 4 of spondylolisthesis (a dislocation of the spinal
column), and lower back syndrome.'' (An exclusion of lower back
syndrome is addressed below). The class II asti anterior plate-screw-
cable fixation devices, ``Spinal intervertebral body fixation
orthosis,'' are ``used to apply a force to a series of vertebrae to
correct `sway back,' scoliosis (lateral curvature of the spine), or
other conditions'' (21 CFR 888.3060).
Scoliosis is a three-plane spinal deformity, but should also be
considered a growth abnormality and a chronic instability. The
predominant feature in scoliosis is a lateral curvature of the thoracic
and lumbar vertebrae in the coronal plane, but is also accompanied by
sagittal plane and rotational deformities. Untreated severe scoliosis
can cause severe cosmetic deformity,degenerative facet joint and
intervertebral disc disease, paraplegia, right heart failure, and
death, and can compromise pulmonary function.
Spinal fractures and dislocations result in loss of bony or
ligamentous integrity that cause spinal instability. Untreated
traumatic spinal instability may lead to progressive spinal deformity,
nonunion, pain, progressive neurologic deficit, and traumatic spinal
stenosis.
Spondylolisthesis, whether degenerative or severe, is generally
regarded as a chronic instability caused by loss of the structural
integrity of posterior element structures, such as the pars
interarticularis, as well as the intervertebral disc. Spondylolisthesis
results in a chronic, sometimes progressive, anterior subluxation of
the superior vertebra over the inferior vertebra. This may be a result
of congenital vertebral anomalies (e.g., deficiency of the facets),
acquired defects (e.g., traumatic pars defects, pedicle or facet
fractures), metabolic bone diseases (e.g., osteogenesis imperfecta,
osteoporosis), or degenerative processes (e.g., degenerative disc
disease). Spondylolisthesis may cause severe back and leg pain,
postural deformity, gait abnormalities due to hamstring tightness, and
progressive neurologic deficits.
FDA believes that, for the purposes of device classification, all
of the above indications can be categorized as acute and chronic
instabilities and deformities.
Lower back syndrome is an ill-defined disorder and is not
considered to be included in the indications of acute and chronic
instabilities and deformities. Sway back, an obsolete term for
lordosis, is a congenital or developmental sagittal plane deformity.
Although 21 CFR 888.3060 states that the asti device is also indicated
for ``other conditions'' that were not specified, the ``other
conditions'' involve instability or a deformity in which fusion is
indicated. Both of these asti devices are used as adjuncts to spinal
fusion, providing immobilization and stabilization of the spinal
segments while fusion takes place. Except for this ill-defined ``lower
back syndrome,'' all these indications constitute acute and chronic
instabilities or deformities. The common purpose of the treatment of
these clinical entities is to prevent the short-term and long-term
sequelae of instability and deformity, such as progressive neurologic
deficit, severe pain, severe cosmetic deformity, pulmonary and
cardiovascular compromise, and even death.
Acute and chronic instabilities or deformities therefore include
scoliosis, fractures, dislocations, and spondylolisthesis, but may also
include spinal tumors, pseudarthrosis, as well as kyphotic deformities.
An extensive laminectomy for spinal stenosis, foraminal stenosis, or
other indications may cause iatrogenic spinal instability by removing
critical stabilizing posterior element structures (Refs. 78 and 118).
Benign and malignant tumors cause instability of the spine by
compromising the structural integrity of the anterior, middle, or
posterior columns of the spine (Refs. 31, 94, 114, 118, and 126).
Segmental defects or loss of posterior elements following tumor
resection require instrumentation and fusion to reestablish spinal
stability and prevent neurologic injury. The pathogenesis of kyphosis
deformities are fracture, inflammation, tumor, congenital malformation,
and laminectomy (Refs. 25, 36, and 118). The goal of treatment is
immediate and long-term stability, nerve and cord decompression, and
correction of angulation. Pseudarthrosis, or failure to achieve a
successful fusion, causes symptomatic instability at the motion segment
(Refs. 104, 169, and 202).
FDA believes that sufficient clinical data exist to justify
including other indications such as scoliosis, spinal tumors, and
failed previous fusion attempts (pseudarthrosis) in the intended use of
the pedicle screw spinal system. The medical literature and data from
IDE clinical investigations demonstrate that the device can effectively
stabilize the spine and adequately maintain spinal alignment while
fusion takes place, and provide adequate evidence that the device can
safely and effectively treat these conditions (Ref. 66). FDA believes
that the risks associated with the use of pedicle screw spinal systems
intended to provide immobilization and stabilization of spinal segments
as an adjunct to fusion in the treatment of these acute and chronic
instabilities and deformities are similar to those of the commercially
available device systems (21 CFR 888.3050 and 888.3060) and that these
rates are clinically acceptable (Ref. 66). FDA believes that the
clinical data from the IDE clinical investigations and the medical
literature adequately support the safety and effectiveness of pedicle
screw spinal systems for these additional indications (Ref. 66).
Moreover, FDA recognizes that these indications for use are similar to
those of commercially available class II spinal fixation devices, such
as the spinal interlaminal fixation orthosis classified under 21 CFR
888.3050 and the spinal intervertebral body fixation orthosis
classified under 21 CFR 888.3060.
FDA believes the medical literature is also supportive of the use
of pedicle screw spinal systems in the treatment of acute and chronic
instabilities and deformities. As described above in section III.B. of
this document, the rates of clinical complications related to the use
of pedicle screw spinal systems in the treatment of acute and chronic
instabilities and deformities are comparable to those for existing
class II devices in terms of mechanical failures (Refs. 3, 5, 19, 22,
24, 32, 35, 37, 43, 47, 50, 51, 58, 59, 60, 73, 77, 79, 87, 89, 90, 94,
95, 107, 109, 110, 113, 116, 122, 125, 150, 151, 152, 162, 163, 164,
173, 183, 185, 186, 187, 191, 192, 193, and 205), soft tissue injuries
(Refs. 25, 26, 27, 37, 46, 47, 49, 60, 74, 106, 112, 113, 126, 127,
147, 153, 183, 185, 187, 191, and 192), pseudarthrosis (Refs. 3, 17,
22, 24, 25, 32, 34, 35, 36, 37, 47, 50, 80, 96, 125, 126, 153, 154,
169, 173, 174, 194, and 205), and reoperation rates (Refs. 50, 51, 60,
74, 86, 119, and 173). The clinical performance is also comparable to
existing spinal devices in terms of fusion rates (Refs. 1, 22, 27, 37,
49, 55, 66, 80, 86, 95, 96, 109, 110, 113, 125, 163, 169, 173, 183,
185, 186, 187, 192, 200, 201, and 202), rates of successful pain (Refs.
2, 18, 25, 27, 37, 80, 86, 95, 97, 109, 110, and 147), function (Refs.
51, 109, 119, 147, 173, and 206), and neurological outcomes (Refs. 39,
49, 55, 80, 90, 107, 153, 154, and 164).
FDA also recognizes the unique benefits of pedicle screw spinal
systems compared to existing spinal instrumentation systems in the
treatment of certain conditions involving severe instability or
deformity. The rigid, segmental, three-column fixation achieved with
pedicle
[[Page 51957]]
screw instrumentation allows successful fixation of severely unstable
spines in cases of tumor (Refs. 31, 77, 94, and 114), severe fracture-
dislocation (Refs. 2, 4, 17, 35, 46, 53, 58, 59, 73, 107, 108, 128,
130, 140, 153, 154, 160, and 178), and severe spondylolisthesis (Refs.
5, 27, 77, 81, 82, 83, 147, 169, and 175). In addition, the pedicle
screw spinal systems provide the only means of posterior attachment of
instrumentation in cases of iatrogenic instability in which the absence
of the posterior elements precludes the use of existing posterior
instrumentation systems, which require laminae or spinous processes for
attachment to the spine (Refs. 113 and 118).
FDA did not find sufficient literature or other clinical data to
support use of the device in the treatment of low back pain. FDA has
determined that low back pain and other conditions not categorized as
an acute or chronic instability or deformity should not be included in
the indications for use unless further data justify their inclusion.
Thus, if the device has such indications for use, the device is a class
III device.
C. Associated Risks
The risks associated with the use of pedicle screw spinal systems
include implant breakage, loss of fixation, nerve root or spinal cord
injury, dural tears, vascular injury, visceral injury, pedicle
fracture, vertebral body penetration, pseudarthrosis, loss of alignment
or reduction, and symptomatic hardware requiring removal. FDA has
determined that these risks are comparable to those associated with the
use of the existing class II spinal fixation devices described in
Secs. 888.3050 888.3060. FDA agrees with the panel that the risks to
health associated with the use of the device are reasonably well
understood and can be adequately controlled through the application of
special controls.
VI. References
The following references have been placed on display in the Dockets
Management Branch (address above) and may be seen by interested persons
from 9 a.m. to 4 p.m., Monday through Friday.
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[[Page 51958]]
32. Bridwell, K. H., T. A. Sedgewick, M. F. O'Brien, L. G. Lenke,
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43. Cotrel, Y., J. Dubousset, and M. Guillaumat, ``New Universal
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44. Covenry, F. R., M. A. Minteer, R. W. Smith, and S. M. Emerson,
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45. Cunningham, B. W., J. C. Sefter, Y. Shono, and P. C. McAfee,
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54. Ebelke, D. K., M. A. Asher, J. R. Neff, and D. P. Kraker,
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55. Esses, S. I., ``The AO Spinal Internal Fixator,'' Spine, 14
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56. Esses, S. I., and D. R. Bednar, ``The Spinal Pedicle Screw:
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57. Esses, S. I., D. J. Botsford, R. J. Huler, and W. Rauschning,
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VII. Environmental Impact
The agency has determined under 21 CFR 25.24(a)(8) and (e)(2) that
this action is of a type that does not individually or cumulatively
have a significant effect on the human environment. Therefore, neither
an environmental assessment nor an environmental impact statement is
required.
VIII. Analysis of Impacts
FDA has examined the impacts of the proposed rule under Executive
Order 12866 and the Regulatory Flexibility Act (Pub. L. 96-354).
Executive Order 12866 directs agencies to assess all costs and benefits
of available regulatory alternatives and, when regulation is necessary,
to select regulatory approaches that maximize net benefits (including
potential economic, environmental, public health and safety, and other
advantages; distributive impacts; and equity). The agency believes that
this proposed rule is consistent with the regulatory philosophy and
principles identified in the Executive Order. In addition, the proposed
rule is not a significant regulatory action as defined by the Executive
Order and so is not subject to review under the Executive Order.
The Regulatory Flexibility Act requires agencies to analyze
regulatory options that would minimize any significant impact of a rule
on small entities. Because this proposal would reduce a regulatory
burden by exempting manufacturers of devices subject to the rule from
the requirements of premarket approval, the agency certifies that the
proposed rule will not have a significant economic impact on a
substantial number of small entities. Therefore, under the Regulatory
Flexibility Act, no further analysis is required.
IX. Comments
Interested persons may, on or before January 2, 1996 submit to the
Dockets Management Branch (address above) written comments regarding
this proposal. Two copies of any comments are to be submitted, except
that individuals may submit one copy. Comments are to be identified
with the name of the device and the docket number found in brackets in
the heading of this document. Received comments may be seen in the
office above between 9 a.m. and 4 p.m., Monday through Friday.
List of Subject in 21 CFR Part 888
Medical devices.
Therefore, under the Federal Food, Drug, and Cosmetic Act and under
authority delegated to the Commissioner of Food and Drugs, it is
proposed that 21 CFR part 888 be amended as follows:
PART 888--ORTHOPEDIC DEVICES
1. The authority citation for 21 CFR part 888 continues to read as
follows:
Authority: Secs. 501, 510, 513, 515, 520, 701 of the Federal
Food, Drug, and Cosmetic Act (21 U.S.C. 351, 360, 360c, 360e, 360j,
371).
2. New Sec. 888.3070 is added to subpart D to read as follows:
Sec. 888.3070 Pedicle screw spinal system.
(a) Identification. A pedicle screw spinal system is a multiple
component device, made of alloys such as 316L stainless steel, 316LVM
stainless steel, 22Cr-13Ni-5Mn stainless steel, unalloyed titanium, and
Ti-6Al-4V, that allows the surgeon to build an implant system to fit
the patient's anatomical and physiological requirements. Such a spinal
implant assembly consists of anchors (e.g., bolts, hooks, and screws);
interconnection mechanisms incorporating nuts, screws, sleeves, or
bolts; longitudinal members (e.g., plates, rods, and plate/rod
combinations); and transverse connectors. The device is intended to
provide immobilization and stabilization of spinal segments in the
treatment of significant medical instability or deformity requiring
fusion with instrumentation including significant medical instability
secondary to spondylolisthesis, vertebral fractures, and dislocations,
scoliosis, kyphosis, spinal tumors, and pseudarthrosis resulting from
unsuccessful fusion attempts.
(b) Classification. Class II (special controls).
Dated: September 29, 1995.
D.B. Burlington,
Director, Center for Devices and Radiological Health.
[FR Doc. 95-24686 Filed 9-29-95; 3:31 pm]
BILLING CODE 4160-01-P