NAME:  EXT.v5             DATE: 2/21/97 1
This guidance was written prior to the February 27, 1997 implementation of FDAs Good
Guidance Practices, GGPs. It does not create or confer rights for or on any person and does not
operate to bind FDA or the public. An alternative approach may be used if such approach
satisfies the requirements of the applicable statute, regulations, or both. This guidance will be
updated in the next revision to include the standard elements of GGPs.
REVIEWERS GUIDANCE CHECKLIST
FOR ORTHOPEDIC EXTERNAL FIXATION DEVICES
Version #5
CONTENTS
I. GENERAL CONTENT OF A REVIEW
II. DESCRIPTION OF PREDICATE(S) AND DEVICE UNDER REVIEW
III. COMPARE THE PREDICATE(S) AND DEVICE UNDER REVIEW
IV. DEVICE TESTING
V. BIBLIOGRAPHY
APPENDICES
Appendix 1. Bone construct classification, frame limb access and frame pin configuration
Appendix 2. Classification of fixator elements (or parts or components) in the system. 
Appendix 3. Materials and design description of each component
Appendix 4. Organization of a summary of a mechanical bench testing report in a 510k review
memo
Appendix 5. Bibliography
Appendix 6. Sample review memo of an external fixation system
I.  GENERAL CONTENT OF A REVIEW
1. Follow the Third Party Review: An Instruction Manual for Conducting Reviews of
Premarket Notifications supplied to Third Parties.
2. Follow the Device Labeling Guidance in the ODE Blue Book.
3. Use and modify as appropriate the boilerplate review memo in the ODE New Reviewer
Training Manual. NAME:  EXT.v5             DATE: 2/21/97 2
II.  DESCRIPTION OF PREDICATE(S) AND DEVICE UNDER REVIEW
1. Identify the type of bones to which the device is to attached (i.e., bone construct
classification) and the types of frame and pin configurations (i.e., the frame limb access and
frame pin configuration) as defined by ASTM F 1541 (see appendix 1 for examples of
possible choices).
2. Compare the intended use of the device to the predicate(s).  21 CFR 888.3030 describes
external fixation devices as single/multiple component metallic bone fixation appliances and
accessories (product code KTT) that ...are used for fixation of fractures of the proximal or
distal end of long bones, such as intracapsular, intertrochanteric, intercervical, supracondylar,
or condylar fractures of the femur; for fusion of a joint; or for surgical procedures that
involve cutting a bone.  Limb lengthening and use in fixation of the hand have also been
identified as preamendment intended uses.  Any other intended uses should be removed or
supported by clinical data. 
External fixation pins are classified in 21 CFR 888.3040 and have the following product
codes: HTY (pin, fixation, smooth), JDW (pin, fixation, threaded) and JEC (component,
traction, invasive).
3. Devices labeled for use in the spine or for dynamitization during bone healing, and devices
which have a structural rigidity significantly lower than the predicate device or which claim
MRI compatibility will not be reviewed by third parties.  These complex issues require
special analysis of the risks, and mechanical and/or animal testing may be necessary which is
beyond the scope of this document.
4. List and classify each of the fixator elements (i.e., parts or components) as defined by STM F
1541.  Possible choices and the suggested order that the components may be listed are given
in appendix 2.
5. In addition to the above list, describe each device component as outlined in the checklist of
material and design parameters in appendix 3.
III.  COMPARE THE PREDICATE(S) AND DEVICE UNDER REVIEW
1. Compare the intended uses, design, materials, properties, etc. of the device under review to
the same parameters of a predicate device, listing all similarities and differences between the
two devices. 
2. Give reasons why each difference does or does not add new or increased risks and complications,
based on current engineering technology and clinical results published about external fixators as
well as based on what has been previously cleared by FDA.  Common complications involving
external fixation devices include the following (Johnson, E.E., page 251):
1. pin-tract infection,
2. ring sequestrae,
3. prolonged healing,
4. distraction of the fracture site,
5. delayed union,
6. bone fracture. NAME:  EXT.v5             DATE: 2/21/97 3
3. Identify potential benefits of the new device compared to predicate devices.
4. Use the above information to justify test requirements as described below. 
IV.  DEVICE TESTING
The reviewer is responsible for assessing the information required to determine safety and
effectiveness based on the particular design parameters of the device under review.  The
following are examples of tests that have been required for previous devices submitted to FDA. 
However, new information may suggest a different approach.  The reviewer should justify test
requirements and conclusions based on supportive references.  If testing of the device is
necessary as described below, a summary of the methods and results should be organized as
suggested in appendix 4.
1. A device which has essentially the same design and materials as the predicate should not
require testing unless there is new information which raises safety and effectiveness
concerns.
2. The smooth or threaded fixation pin components (or their equivalent) that contact body
tissues are always metal and are generally medical grade CoCrMo, Ti6Al4V or 316 LVM
stainless steel.  Other types of pin materials or combinations of materials should
demonstrate a biological response at least as good as a predicate or substantially
equivalent device when tested according to ISO 10993 for Medical Devices.
3. If the new device does not have the same or a higher estimated rigidity compared to the
predicate device based on dimensions (given that the materials in the predicate have the
same or higher elastic modulus compared to the new device) rigidity should be evaluated
either in bench testing or in an animal model.
4. The static load to failure of the entire construct is only necessary for new designs in
which the rigidity of the construct significantly differs from predicate designs.
5. If any interconnection design is not similar to a predicate design, loosening between parts
at that interconnection should be evaluated.  Cyclic loading is preferred, though static
loading may be considered acceptable if properly rationalized.  If the loads applied at the
interconnection can be demonstrated to be the same as expected clinical loads, only the
two joined parts need to be included in the test.
6. If the design under review has any stress risers not present in the predicate design, fatigue
testing of the assembly should be performed, or a rationale for why such testing is not
necessary should be presented. NAME:  EXT.v5             DATE: 2/21/97 4
7. Any reasonably known and available animal or clinical data about devices containing
similar materials and designs should be summarized in a table.  Additional animal or
clinical data may be required if the bench testing methods or results of other tests raise
concerns.
V. BIBLIOGRAPHY
Provide a bibliography if references are given (e.g., appendix 5). NAME:  EXT.v5             DATE: 2/21/97 5
Appendix 1.   Bone construct classification, frame limb access and frame pin configuration
The device under review and the predicate device should be described using the terminology
defined in the ASTM F 1541 and organized as shown below (the section in ASTM F 1541 which
defines the term is given).  Any other features not included in this list should be added where
appropriate.
Fixator-Bone Construct Classifications  6.3
Long bone  6.3.1.1
Articular joint (arthrodesis) 6.3.1.2
Pelvis  6.3.1.3
Spinal  6.3.1.4
Halo (skull) 6.3.1.5
Small bones
Limb lengthening
Frame limb access 6.3.3
Unilateral  6.3.3.1
Multilateral  6.3.3.2
Bilateral
Triangular
Quadrilateral
Biplanar
Ring fixators   6.3.8
Half-ring
Circular or full-ring
Frame pin configuration
One-plane   6.3.4.1
Multi-plane 6.3.4.2 NAME:  EXT.v5             DATE: 2/21/97 6
Appendix 2.   Classification of fixator elements (or parts or components) in the system.
The fixator elements for both the device under review and the predicate device should be
described using the terminology defined in the ASTM F 1541 and organized into a list as
suggested below (the section in ASTM F 1541 which defines the term is given).  Any other
design features not included in this list should be added where appropriate.
Anchorage elements  5.6
Wire-fixed  6.3.5.2
Wires  6.1.1
Stoppers ("olives")
Pin-fixed  6.3.5.1
Pins  6.1.2
Ends gripped by frame  6.1.2.1
Half-pins
Through-and-through pins or full-pins
Number of cortices penetrated
Surface 6.1.2.3
Smooth
Threaded
Self-drilling
Self-tapping
Type of bone to be penetrated 6.1.2.2
Cortical bone
Cancellous bone
Cross section  6.1.2.4
Constant
Shouldered
Tapered
Used individually or in clusters
Screws 6.1.3
Cortex clamps (or claws or prongs)  6.1.4
Hybrid coupling  6.3.5.3
Bridge elements (bar or rod)  5.7, 6.2
Simple bridge elements  5.7.1
Complex bridge elements  5.7.2
Telescoping
Dynamic
Connectors  5.8
Articulation  5.10
Non-adjustable joints  5.11
Independent control 6.3.7
Multi-pin clamps  6.3.7
Pin cluster   6.3.7 NAME:  EXT.v5             DATE: 2/21/97 7
Appendix 3. Materials and design description of each component
For each part of each component of both the device under review and, as much as possible, the
predicate device, provide the following:
names
model numbers
size ranges
identification on a photo or drawing of the fixator assembly (i.e., frame plus bony
anchorage elements and their associated connectors (ASTM F 1541, 5.9) or fixator-bone
construct and construct sub-unit (ASTM F 1541, 6.3.2))
drawing and/or description depicting the function and where it fits with other parts of the
device and tissues
types of interfaces (i.e., articulating, fixed mating parts, coatings, tissues)
detailed engineering drawing with tolerances (as necessary)
material composition, to include the following:
sources of more detailed information (e.g., other FDA document submission
numbers or other references)
description of the material (e.g., 316 LVM stainless steel), including processed
condition (e.g. annealed, 20% cold worked)
name and number of applicable voluntary standards
differences between the final product and the standard
trade names (optional)
manufacturers (optional)
new processing methods, if any NAME:  EXT.v5             DATE: 2/21/97 8
Appendix 4. Organization of a summary of a mechanical bench testing report in a 510k
review memo
The review memo should provide a summary of each mechanical bench testing report submitted
in the 510k.  This should include a list of the essential test parameters and results as well as the
persons/labs generating the data.  All reviews should be organized the same way.  For example, a
summary of each report should include (where applicable), but is not limited to the following:
REFERENCE
Report title
Investigators' names
Facility Performing the test
Name
Address
Phone Number
Dates
Test initiation
Test completion
Final report completion
TEST IDENTIFICATION
Standard  #
Standard name
Specific test name
SAMPLE DESCRIPTION (Design, Materials, Processing methods)
Test sample description
Control description
Selection criteria
Differences vis a vis final products
MEDIUM SURROUNDING THE SAMPLES BEFORE AND DURING TESTING
Storage conditions prior to testing
Volume
Composition
pH
Temperature        
Flow
Test model or subject which contacts the specimens
MECHANICAL LOADING
Direction (e.g., normal to the longitudinal axis)
Mode (e.g., 3 point bending)
Load point (e.g., at the center of the rod)
Magnitude (e.g., 10 lbs min., 100 lbs max.)
Time (e.g., presoaked 10 days)
Rate (e.g., 1 Hz)
Cycles (e.g., 106) NAME:  EXT.v5             DATE: 2/21/97 9
TEST SETUP
Schematic or photograph
Description of grips or potting medium interfacing with samples
Test equipment calibration (schedule, methods and data)
Rationale for choices of parameters, values, etc.
Methods of specimen examination (e.g., failure analysis)
Number of samples tested, with statistical justification
Chronological description of the test procedures
Deviations from referenced protocols and standards
RESULTS
Discussion of the data and possible mechanisms of failure
List of conclusions
Discussion of the objective/hypothesis
Simplifications and assumptions and their clinical implications NAME:  EXT.v5             DATE: 2/21/97 10
Appendix 5. Bibliography
ASTM F 1541 Standard Classification of External Skeletal Fixators
Anderson, R.C.:  'Final Report of the Structural Evaluation of the DDC Circular Fixator'.  FDA Document
K904932, Internat. Med. Prod. Corp. (pub.), 1990.
Aro, H.T.; et al.:  'Mechanical Characteristics of an Upper-Extremity External Fixator'.  Clin. Orthop. Rel.
Res.,  253, pp. 240, Ap., 1990.
Egan, J.M.; Shearer, J.R.:  'Behavior of an External Fixation Frame Incorporating an Angular Separation of
the Fixator Pins'.  Clin. Orthop. Rel. Res.,  223, pp. 265, Oct., 1987.
Evans, G.; et al.:  'External Fixation of fractures of the Tibia:  Clinical Experience of a New Device'. 
Injury,  19, pp. 73, 1988.
Figgie, M.P.; et al.:  'Results of Reconstruction for Failed Total Elbow Arthroplasty'.  Clin. Orthop. Rel.
Res.,  253, pp. 123, Ap., 1990.
Figgie, M.P.; et al.:  'The Results of Treatment of Supracondylar Fracture Above Total Knee Arthroplasty'. 
J. of Arthroplasty,  5, pp. 267, Sept., 1990.
Fjeld, T.O.; Steen, H.:  'Growth Retardation Following Experimental Limb Lengthening by Epiphyseal
Distraction'.  Acta Orthop. Scand.,  61, pp. 52, Suppl.235, 1990.
ISO Test Methods for External Fixation Devices
Johnson, E.E.; et al.:  'Delayed Intramedullary Nailing After Failed External Fixation of the Tibia'.  Clin.
Orthop. Rel. Res.,  # 253, pp. 251, Ap., 1990.
Kelly, P.J.; et al.:  'Reaction of the Circulatory System to Injury and Regeneration'.  Cli. Orthop. Rel. Res., 
254, pp. 275, May, 1990.
Kenwright, J.:  'Leg Length Inequality'.  Current Orthop.,  3, pp. 176, July, 1989.
Nalebuff, E.A.:  'Surgery for Rheumatoid Arthritis:  Upper Limb Surgery of the Wrist and Hand'.  Current
Orthop.,  3, pp. 14, Jan., 1989.
Paley, D.:  'Problems, Obstacles, and Complications of Limb Lengthening by the Ilizarov Technique'.  Clin.
Orthop. Rel. Res.,  250, pp. 81, Jan., 1990.
Schmalholz, A.:  'External Skeletal Fixation Versus Cement Fixation in the Treatment of Redislocated
Colles' Fracture'.  Clin. Orthop. Rel. Res., J.B. Lippincott Co. (pub.), 254, pp. 236, May, 1990.
Smith, S.R.; et al.:  'Effect of Fracture Fixation on Cortical Bone Blood Flow'.  J. of Orthopaedic Research,
 8, pp. 471,  1990.
Solgaard, S.:  'External Fixation or a Cast for Colles' fracture'.  Acta Orthop. Scand.,  60, pp. 387, Aug.,
1989.
Whitelaw, G.P.; et al.:  'Ender rods Versus External Fixation in the Treatment of Open Tibial Fractures'. 
Clin. Orthop. Rel. Res.,  # 253, pp. 258, Ap., 1990. NAME:  EXT.v5             DATE: 2/21/97 11
Appendix 6. Sample review memo of an external fixation system
KEY WORDS      ext  wire  ti 64  coa  anodize  color  ss
5 1 0 (k)   R E V I E W
DATE February 21, 1997
FROM  Xxx Xxxxxxxxx
TO  File
DOCUMENT #  K000000
SPONSOR Xxxxxxxx
DEVICE NAME Xxxxxxxx External Fixation System
CLASS KTT 2 888.3030 APPLIANCE, FIXATION, NAIL/BLADE/PLATE
COMBINATION, MULTIPLE COMPONENT
DISEASE/USE Open and closed fracture fixation, nonunions, limb lengthening, soft and hard tissue
deformities or defects.  This material is for nickel sensitive patients.
REASON FOR APPLICATION:  Change in materials (from 316 LVM SS to Ti-6Al-4V)
DECISION       SE
The change in material did not significantly affect the rigidity or fatigue properties of the device.  The static
strength was lower for the  Ti-6Al-4V wire, however:
Even the xxxx N failure load of the Ti alloy wire exceeds 3 times body weight (2000 N) by 900 N, i.e.,
xx% of 2000 N. 
More than one wire is used in parallel, so the load is shared.
STERILITY      nonsterile
FILE           bonfix\ext              RECNO     883   NAME:  EXT.v5             DATE: 2/21/97 12
ASTM F 1541 CLASSIFICATION OF THE Xxxxxxxx EXTERNAL FIXATION SYSTEM
The following is a list of descriptors defined in ASTM F 1541 to aid in identifying and classifying this
external fixation system.  Because this device was cleared in a previous 510k, this review memo only
describes in detail components which are new to this system, i.e., the 2 wires and the washer (identified by *
below).
Overall system
Fixator-Bone Construct Classification
Long bone
Limb lengthening
Frame limb access
Multilateral
Ring fixator
Circular
Frame pin configuration
One-plane
Anchorage elements
Wire-fixed
Wires
Smooth*
Olive*
Washer*
Bridge elements
Complex
Connectors 
Non-adjustable joints 
DESCRIPTION OF EACH COMPONENT UNDER REVIEW IN THIS 510K
COMPONENT 1    washer
MATERIAL       Ti-6Al-4V  STANDARD #  ISO 5832-3  
INTERFACESARTICULATIONS  none   MATING PARTS  olive wire 
TISSUE FIXATION  bone  COATINGS  anodization  
DESIGN 7 mm OD.  Distributes the load applied by the olive wire over a greater area of the
bone.
COMPONENT 2    olive wire
MATERIAL        Ti-6Al-4V           STANDARD #  ISO 5832-3  
INTERFACES ARTICULATIONS  none  MATING PARTS  washer, frame
TISSUE FIXATION  bone COATINGS  anodization
DESIGN 1.8 x 400 mm.  Creates interfragmentary compression and adds greater stability.
COMPONENT 3    smooth wire
MATERIAL Ti-6Al-4V  STANDARD #  ISO 5832-3  
INTERFACES ARTICULATIONS  none   MATING PARTS  frame
TISSUE FIXATION  bone  COATINGS  anodization    
DESIGN 1.8 x 400 mm.  Creates interfragmentary compression and adds greater stability. NAME:  EXT.v5             DATE: 2/21/97 13
COMPONENT 4    anodized coating
STANDARD #      xxxxxx SEE ALSO  Kxxxxxx
DESIGN This blue oxide coating allows the Ti alloy parts to be distinguished from SS parts.
COMPARABLE PREDICATE DEVICES
As  required by 21 CFR  807.87  (f), the  device  under  review  in  this  510k  is  compared  for  substantial
equivalence to a legally marketed predicate device which was found to be substantially equivalent in a 510k
(predicate device), viz., Kxxxxxx Xxxxxxxx External Fixation System:   components 1-3 described above but
made of 316 LVM SS.
The  differences  in  the  design  (compared  to  predicate  devices)  do  not  raise  new  types  of  safety  and
effectiveness questions (risks) not seen before in similar devices.  The same risks occur in both devices.
TECHNOLOGICAL CHARACTERISTICS: 
Possible clinical complications/risks for the device under review may include the following:
1. pin-tract infection,
2. ring sequestrae,
3. prolonged healing,
4. distraction of the fracture site,
5. delayed or non-union,
6. bone fracture.
Non-union  of  the  original  fracture  and  resorption  of  bone  after  fracture  fixation  often  initiate  these
complications so the external fixator submitted in this 510k was evaluated to determine the likelihood of non-
union or bone resorption by the following tests:
RIGIDITY (OR DEFLECTION) MEASUREMENTS
Xsss, X.; Yyyyyyyyy, Y. 1996 measured the stiffness of the external fixator wires to determine the clinical
significance of differences in materials.  Testing was conducted at Zzzzzzzz 01/96.  The 10 test samples were
Ti-6Al-4V 1.8 mm wire under a tension of xx or yyy Kg.  The 10 control samples were SS with the same
characteristics.  Samples were loaded normal to the wire axis in a pseudo 3 point bending at x mm/min at the
center of the wire.  Each sample was loaded x times and the final rigidity used in comparisons.  The rigidity of
the test and control samples was xx +- x.x and yy +- y.y N/mm respectively.  The z% difference in stiffness
between the two types of wire was not significant.
STATIC FAILURE OF THE DEVICE
This testing determines the static load to failure of the entire construct.  Xxxxx, X.; Yyyyyyyyy, Y. 1994 (page
4) measured the strength of external fixator wire.  Samples were loaded in parallel to the wire axis in tension
at  x  mm/min.    The  results  for  the  Ti  test  and  SS  control  samples  were  xxxx  and  yyyy  N NAME:  EXT.v5             DATE: 2/21/97 14
respectively.  The SD was xxx and yy N respectively, so the Ti wire load to failure was significantly below
that of the SS wire.  The lower Ti wire strength may not be a problem for two reasons:
Even the xxxx N failure load of the Ti alloy wire exceeds 3 times body weight (2000 N) by 900 N, i.e.,
yy% of xxxx N. 
More than one wire is used in parallel, so the load is shared.
FATIGUE FAILURE AND LOOSENING BETWEEN PARTS
Xxxxx, X.; Yyyyyyyyy, Y. 1994 (page 4) evaluated the cyclic fatigue strength of external fixator wire. 
Samples were loaded normal to the wire axis in 3 point bending at xx-yyy N (z Hz) at the center of wire until
failure.  Failure of the Ti test and SS control samples occurred after xxxxx and yyyyy cycles respectively for
the 1.8 mm wires.  The difference was not significant.
THERMAL NECROSIS DUE TO DRILLING THE WIRE THROUGH THE BONE
Xxxxx, X.; Yyyyyyyyy, Y. 1994 (page 4) measured bone temperatures during drilling of external fixation wire
through simulated bone (Last-A-Foam) to determine any differences in results due to differences in materials.
Testing was conducted at Zzzzzzzz 05/01/94. Samples were loaded xx N during drilling along the wire axis. 
The Ti wire and SS wire heated the bone model to xx and yy C, but the SD was around x and y C respectively,
so there was no significant difference. 
Differences between the two materials may have made a difference in the amount of heat generated if
lubricant or real bone were used.  Therefore, I do not feel this test accurately determines any differences
between the SS and Ti wires.  The actual temperatures should be lower if lubricant is used, but the effect of
not using real bone is unknown.  This test is not critical to safety and effectiveness, so I do not recommend
requesting further information.
SUMMARY OF INFORMATION SUPPORTING DECISION/RECOMMENDATION:
This device has equivalent intended use, has similar promotional claims, conforms to similar standards, and
has equivalent technological characteristics to predicate devices.
REVIEWED BY:                                             
 Xxx    Xxxxxxxxx
ATTACHMENTS:
design drawings, photos, predicate device, intended use statement NAME:  EXT.v5             DATE: 2/21/97 15
CONTACT HISTORY:
The following is a chronological listing of all requests for information made by Xxx Yyyyyyy to the firm
regarding this 510k, followed by a summary of the firm's response in their next correspondence (the firm's
response is indented below each request):
As per 21 CFR 807.87(h), I advised Xxx Xxxxx 7-29-96, 2 pm that there was insufficient information to
make a determination concerning substantial equivalence.  I then requested the following information:
1. The Ti wire load to failure was significantly below that of the SS wire.  Discuss the effect of this on
clinical outcomes.
FDA received an adequate response to this request.
2. Provide information on differences in fixator rigidity using SS versus Ti wire.  The device under
review is made out of a material with a lower modulus compared to the predicate, which may result in
a lower rigidity.  Rigidity affects bone resorption and union of the fracture.  Too little rigidity may lead
to instability and nonunion.
FDA received an adequate response to this request.