ASTM F1541-02(2007)

Standard Specification and Test Methods for External Skeletal Fixation Devices

SCOPE
1.1 This specification provides a characterization of the design and mechanical function of external skeletal fixation devices (ESFDs), test methods for characterization of ESFD mechanical properties, and identifies needs for further development of test methods and performance criteria. The ultimate goal is to develop a specification, which defines performance criteria and methods for measurement of performance-related mechanical characteristics of ESFDs and their fixation to bone. It is not the intention of this specification to define levels of performance or case-specific clinical performance of the devices, as insufficient knowledge is available to predict the consequences of the use of any of these devices in individual patients for specific activities of daily living. Furthermore, it is not the intention of this specification to describe or specify specific designs for ESFDs.
1.2 This specification describes ESFDs for surgical fixation of the skeletal system. It provides basic ESFD geometrical definitions, dimensions, classification, and terminology; material specifications; performance definitions; test methods; and characteristics determined to be important to the in-vivo performance of the device.
1.3 This specification includes a terminology and classification annex and five standard test method annexes as follows:
1.3.1 Classification of External Fixators.
1.3.2 Test Method for External Skeletal Fixator Connectors.
1.3.3 Test Method for Determining In-Plane Compressive Properties of Circular Ring or Ring Segment Bridge Elements.
1.3.4 Test Method for External Skeletal Fixator Joints.
1.3.5 Test Method for External Skeletal Fixator Pin Anchorage Elements.
1.3.6 Test Method for External Skeletal Fixator Subassemblies.
1.3.7 Test Method for External Skeletal Fixator/Constructs Subassemblies.
1.4 A rationale is given in Appendix X1.
1.5 The values stated in SI units are to be regarded as the standard.
1.6 The following safety hazards caveat pertains only to the test method portions (Annex A2 - Annex A6):
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 14-Jun-2007
• ICS: 11.120.20 - Wound dressings and compresses
• Technical Committee: F04 - Medical and Surgical Materials and Devices
• Drafting Committee: F04.21 - Osteosynthesis

Relations

• Replaces: ASTM F1541-02 - Standard Specification and Test Methods for External Skeletal Fixation Devices
• Effective Date: 15-Jun-2007
• Replaced By: ASTM F1541-02(2007)e1 - Standard Specification and Test Methods for External Skeletal Fixation Devices
• Effective Date: 15-Jun-2007

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: F 1541 – 02 (Reapproved 2007)
Standard Specification and Test Methods for
External Skeletal Fixation Devices
This standard is issued under the fixed designation F1541; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 1.4 A rationale is given in Appendix X1.
1.5 The values stated in SI units are to be regarded as the
1.1 This specification provides a characterization of the
standard.
design and mechanical function of external skeletal fixation
1.6 The following safety hazards caveat pertains only to the
devices (ESFDs), test methods for characterization of ESFD
test method portions (Annex A2-Annex A6):
mechanical properties, and identifies needs for further devel-
1.7 This standard does not purport to address all of the
opment of test methods and performance criteria.The ultimate
safety concerns, if any, associated with its use. It is the
goal is to develop a specification, which defines performance
responsibility of the user of this standard to establish appro-
criteria and methods for measurement of performance-related
priate safety and health practices and determine the applica-
mechanicalcharacteristicsofESFDsandtheirfixationtobone.
bility of regulatory limitations prior to use.
It is not the intention of this specification to define levels of
performance or case-specific clinical performance of the de-
2. Referenced Documents
vices, as insufficient knowledge is available to predict the
2.1 ASTM Standards:
consequences of the use of any of these devices in individual
A938 Test Method for Torsion Testing of Wire
patients for specific activities of daily living. Furthermore, it is
D790 TestMethodsforFlexuralPropertiesofUnreinforced
not the intention of this specification to describe or specify
andReinforcedPlasticsandElectricalInsulatingMaterials
specific designs for ESFDs.
E4 Practices for Force Verification of Testing Machines
1.2 This specification describes ESFDs for surgical fixation
F67 Specification for Unalloyed Titanium, for Surgical
of the skeletal system. It provides basic ESFD geometrical
Implant Applications (UNS R50250, UNS R50400, UNS
definitions, dimensions, classification, and terminology; mate-
R50550, UNS R50700)
rial specifications; performance definitions; test methods; and
F 90 Specification for Wrought Cobalt-20Chromium-
characteristics determined to be important to the in-vivo
15Tungsten-10Nickel Alloy for Surgical Implant Applica-
performance of the device.
tions (UNS R30605)
1.3 This specification includes a terminology and classifi-
F 136 Specification for Wrought Titanium-6Aluminum-
cationannexandfivestandardtestmethodannexesasfollows:
4Vanadium ELI (Extra Low Interstitial)Alloy for Surgical
1.3.1 Classification of External Fixators—Annex A1.
Implant Applications (UNS R56401)
1.3.2 Test Method for External Skeletal Fixator
F138 Specification for Wrought 18Chromium-14Nickel-
Connectors—Annex A2.
2.5Molybdenum Stainless Steel Bar and Wire for Surgical
1.3.3 Test Method for Determining In-Plane Compressive
Implants (UNS S31673)
Properties of Circular Ring or Ring Segment Bridge
F366 Specification for Fixation Pins and Wires
Elements—Annex A3.
F543 Specification and Test Methods for Metallic Medical
1.3.4 Test Method for External Skeletal Fixator Joints—
Bone Screws
Annex A4.
F544 Reference Chart for Pictorial Cortical Bone Screw
1.3.5 Test Method for External Skeletal Fixator Pin Anchor-
Classification
age Elements—Annex A5.
F1058 Specification for Wrought 40Cobalt-20Chromium-
1.3.6 Test Method for External Skeletal Fixator
16Iron-15Nickel-7Molybdenum Alloy Wire and Strip for
Subassemblies—Annex A6.
Surgical Implant Applications (UNS R30003 and UNS
1.3.7 Test Method for External Skeletal Fixator/Constructs
R30008)
Subassemblies—Annex A7.
1 2
This specification is under the jurisdiction of ASTM Committee F04 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Medical and Surgical Materials and Devices and is the direct responsibility of
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Subcommittee F04.21 on Osteosynthesis. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved June 15, 2007. Published June 2007. Originally the ASTM website.
published as F1541–94. Last previous edition approved in 2002 as F1541–02. Withdrawn.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F 1541 – 02 (2007)
F1264 Specification and Test Methods for Intramedullary adequacy of their intrinsic mechanical stiffness, or strength, or
Fixation Devices both, is critical to overall fixator performance. A test method
F1472 Specification for Wrought Titanium-6Aluminum- forevaluatingthemechanicalperformanceofESFDconnector
4VanadiumAlloy for Surgical ImplantApplications (UNS elements is described in Annex A2.
R56400) 6.2.2 ESFDs involving ring-type bridge elements are used
F1713 Specification for Wrought Titanium-13Niobium- widely both for fracture treatment and for distraction osteo-
13Zirconium Alloy for Surgical Implant Applications genesis. The anchorage elements in such fixators usually are
(UNS R58130) wires or thin pins, which pass transverse to the bone long axis
andwhicharetensioneddeliberatelytocontrolthelongitudinal
3. Terminology
stiffness of the fixator. Tensioning these wires or pins causes
3.1 Definitions—The definitions of terms relating to exter- appreciable compressive load in the plane of the ring element.
nal fixators are described in Annex A1.
A test method for evaluating the mechanical performance of
ESFDringelementsinthisloadingmodeisdescribedinAnnex
4. Classification
A3.
4.1 Externalskeletalfixatorsaremodulardevicesassembled
6.2.3 ThehighloadsoftendevelopedatESFDjunctionsites
from component elements. are of concern both because of potentially excessive elastic
4.2 Test methods can address individual elements, for ex-
deformation and because of potential irrecoverable deforma-
ample, anchorage elements, bridge elements; subassemblies of tion. In addition to the connecting element itself (Annex A2),
elements,forexample,connectors,joints,ringelements;orthe
overall performance of the junction also depends on the
entire fixator. interface between the connecting element and the anchorage,
4.3 Tests of an entire assembled fixator may include the
or bridge elements, or both, which it grips. A test method for
fixator alone, or alternatively, the fixator as anchored to a evaluating the overall strength, or stiffness, or both, at an
representation of the bone(s) upon which it typically would be
externalfixatorjoint,asdefinedinAnnexA1astheconnecting
mounted in clinical usage. element itself plus its interface with the anchorage, or bridge,
or both, elements, which it grips, is described in Annex A4.
5. Materials
6.2.4 The modular nature of many ESFD systems affords
5.1 All ESFDs made of materials that have an ASTM
thesurgeonparticularlygreatlatitudeastoconfigurationofthe
standard shall meet those requirements given in ASTM Stan-
frame subassembly, as defined in Annex A1 as the bridge
dards listed in 2.1.
elements plus the connecting elements used to join bridge
elements, but specifically excluding the anchorage elements.
6. Performance Considerations and Test Methods
Since configuration of the frame subassembly is a major
6.1 Individual Components—The anchorage pins through
determinant of overall ESFD mechanical behavior, it is impor-
which an ESFD is attached to a skeletal member or members
tant to have procedures for unambiguously characterizing
typically experience high flexural, or torsional loads, or both.
frame subassemblies, both geometrically and mechanically.
Often, the majority of the overall compliance of an ESFD is in
Test methodology suitable for that purpose is described in
its anchorage elements. A test method for evaluating the
Annex A6.
mechanical performance of an ESFD anchorage element in
6.3 Entire Assembled Fixator—No test methods are yet
either of these loading modes is described in Annex A5.
approved for entire assembled fixators.
6.2 Subassemblies of Elements:
7. Keywords
6.2.1 The sites of junction between ESFD anchorage ele-
ments, for example, pins, and bridge elements, for example, 7.1 anchorageelement;bending;bridgeelement;connector;
rods, normally require specialized clamping or gripping mem-
external skeletal fixation device; fracture fixation; joints;
bers, known as connecting elements. Often, connecting ele- modularity; orthopedic medical device; osteosynthesis; ring
ments are subjected to high loads, especially moments, so
element; subassembly (frame); terminology; torsion
F 1541 – 02 (2007)
ANNEXES
(Mandatory Information)
A1. CLASSIFICATION OF EXTERNAL SKELETAL FIXATORS
A1.1 Scope A1.5.1.2 The individual parts (or modules of individual
parts)fromwhichtheenduserassemblesthefixatoraretermed
A1.1.1 This classification covers the definitions of basic
its elements.
terms and considerations for external skeletal fixation devices
A1.5.2 AnESFDnormallyisconfiguredtospanamechani-
(ESFDs) and the mechanical analyses thereof.
cal discontinuity in the host bone that otherwise would be
A1.1.2 It is not the intent of this classification to define
unable to transmit one or more components of the applied
levels of acceptable performance or to make recommendations
functional load successfully.This bony discontinuity is termed
concerning the appropriate or preferred clinical usage of these
the mechanical defect.
devices.
A1.5.3 Examples of mechanical defects are fracture sur-
A1.1.3 This standard does not purport to address all of the
faces, interfragmentary callus, segmental bone gaps, articular
safety concerns, if any, associated with its use. It is the
surfaces, neoplasms, and osteotomies.
responsibility of the user of this standard to establish appro-
A1.5.4 Coordinate System(s)—The relative positions of the
priate safety and health practices and determine the applica-
bones or bone segments bordering the mechanical defect
bility of regulatory limitations prior to use.
should be described in terms of an orthogonal axis coordinate
system (Fig. A1.1).
A1.2 Referenced Documents
A1.5.4.1 Where possible, coordinate axis directions should
A1.2.1 ASTM Standards:
be aligned perpendicular to standard anatomical planes, for
F366 Specification for Fixation Pins and Wires
example,transverse(horizontaloraxial),coronal(frontal),and
F543 Specification and Test Methods for Metallic Medical
sagittal (median).
Bone Screws
A1.5.4.2 Where possible, translation directions should be
F544 Reference Chart for Pictorial Cortical Bone Screw
consistent with standard clinical conventions, for example,
Classification
ventral (anterior), dorsal (posterior), cranial (cephalad or supe-
rior), caudal (inferior), lateral, or medial.
A1.3 Background
A1.5.4.3 Rotation measurement conventions must follow
the right-hand rule and, where possible, should be consistent
A1.3.1 ESFDs are in widespread use in orthopedic surgery,
with standard clinical terminology, for example, right or left
primarily for applications involving fracture fixation or limb
lateral bending, flexion, extension, and torsion.
lengthening,orboth.Themechanicaldemandsplacedonthese
A1.5.5 Abase coordinate system (X, Y, Z) should be affixed
devices often are severe. Clinical success usually depends on
to one of the bones or major bone segments bordering the
suitablemechanicalintegrationoftheESFDwiththehostbone
mechanical defect. This bone or bone segment is termed the
or limb.
base segment, S , and serves as a datum with respect to which
b
A1.3.2 It is important, therefore, to have broadly accepted
pertinent motion(s) of bone segments or fixator elements, or
terminology and testing standards by which these devices can
both, can be referenced. Depending on context, S may be
b
be described and their mechanical behaviors measured.
defined as being on either the proximal or the distal side of a
A1.3.3 Useful terminology and testing standards must take
mechanical defect.
into account that the modular nature of most ESFDs deliber-
A1.5.6 The other bone(s) or bone segment(s) bordering the
ately affords a great deal of clinical latitude in configuring the
mechanical defect, whose potential motion(s) with respect to
assembled fixator.
S is of interest, is termed the mobile segment(s), S.If
b m
necessary, a local right-handed orthogonal coordinate system
A1.4 Significance and Use
(x, y, z) may be embedded within the S (s).
m
A1.4.1 The purpose of this classification is to establish a
A1.5.7 Degrees of Freedom:
consistent terminology system by means of which these ESFD
Describing the position, or change in position, of S relative
m
configurations can be classified. It is anticipated that a com-
to S requires specifying one or more independent variables.
b
panion testing standard using this classification system will
These variables will be termed positional degrees of freedom
subsequently be developed.
(P-DOF).
A1.5.7.1 Depending on context, this may involve as many
A1.5 Basis of Classification
as six variables (three translation and three orientation).
A1.5.1 An assembled ESFD and the bone(s) or bone ana-
A1.5.7.2 Also depending on context, P-DOFs may be used
log(s) to which it is affixed constitute a fixator-bone construct. to describe motions of interest in various magnitude ranges.
A1.5.1.1 The assembled ESFD itself, apart from the host For example, P-DOFs may be used to describe one or more
bone, is termed the fixator assembly. components of visually imperceptible motion, for example,
F 1541 – 02 (2007)
A1.5.9.2 Unlocked degrees of freedom in which motion is
induced actively by external energy input from devices asso-
ciatedwiththefixatoraretermed actuateddegreesoffreedom.
A1.5.9.3 Anunlockeddegreeoffreedominwhichmotionis
unopposed by a specific design mechanism is termed an
unresisted unlocked degree of freedom. Incidental friction in a
dynamizing element shall not be construed as representing
deliberately resisted motion; however, conditions involving
untoward resistance to motion, for example, substantial bind-
ing friction, in a supposedly unresisted degree of freedom
should be identified.
A1.5.10 For adjustment or unlocked DOFs, the extrema of
angular or translational displacement between which motion is
permitted before encountering a fixed or adjustable constraint
are termed that DOF’s range of motion (ROM).
A1.5.11 A fixator assembly consists of a structurally p
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