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Reviewers Guidance Checklist |
This guidance was written prior to the February 27, 1997 implementation of FDA's Good Guidance Practices, GGP's. 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 GGP's.
I. GENERAL CONTENT OF A REVIEW
II. DESCRIPTION OF PREDICATE(S) AND DEVICE UNDER REVIEW
III. COMPARE THE PREDICATE(S) AND DEVICE UNDER REVIEW
AppendicesAppendix 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 6. Sample review memo of an external fixation system
I. GENERAL CONTENT OF A REVIEW
II. DESCRIPTION OF PREDICATE(S) AND DEVICE UNDER REVIEW
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).
III. COMPARE THE PREDICATE(S) AND DEVICE UNDER REVIEW
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.
V. BIBLIOGRAPHY
Provide a bibliography if references are given (e.g., appendix 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 6.3Frame limb access 6.3.3
Frame pin configuration
One-plane 6.3.4.1
Multi-plane 6.3.4.2
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
Simple bridge elements 5.7.1
Articulation 5.10
Non-adjustable joints 5.11
Independent control 6.3.7
Multi-pin clamps 6.3.7
Pin cluster 6.3.7
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:
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
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:
REFERENCEDirection | (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) |
TEST SETUP
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.
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 |
|
||
FILE |
bonfix\ext |
RECNO |
883 |
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 systemWires
Smooth*
Olive*
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. |
| ||
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 |
|
STANDARD # ISO 5832-3 |
INTERFACES | ARTICULATIONS none | MATING PARTS frame |
|
COATINGS anodization | |
DESIGN |
1.8 x 400 mm. Creates interfragmentary compression and adds greater stability |
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:
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:
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 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
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:
FDA received an adequate response to this request.
FDA received an adequate response to this request.
Uploaded on August 13, 1998
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