ASTM F1541-02(2011)
(Specification)Standard Specification and Test Methods for External Skeletal Fixation Devices
Standard Specification and Test Methods for External Skeletal Fixation Devices
SIGNIFICANCE AND USE
A1.4.1 The purpose of this classification is to establish a consistent terminology system by means of which these ESFD configurations can be classified. It is anticipated that a companion testing standard using this classification system will subsequently be developed.
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—Annex A1.
1.3.2 Test Method for External Skeletal Fixator Connectors—Annex A2.
1.3.3 Test Method for Determining In-Plane Compressive Properties of Circular Ring or Ring Segment Bridge Elements—Annex A3.
1.3.4 Test Method for External Skeletal Fixator Joints—Annex A4.
1.3.5 Test Method for External Skeletal Fixator Pin Anchorage Elements—Annex A5.
1.3.6 Test Method for External Skeletal Fixator Subassemblies—Annex A6.
1.3.7 Test Method for External Skeletal Fixator/Constructs Subassemblies—Annex A7.
1.4 A rationale is given in Appendix X1.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 The following safety hazards caveat pertains only to the test method portions (Annex A2-Annex A6):
1.7 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.
A1.1.1 This classification covers the definitions of basic terms and considerations for external skeletal fixation devices (ESFDs) and the mechanical analyses thereof.
A1.1.2 It is not the intent of this classification to define levels of acceptable performance or to make recommendations concerning the appropriate or preferred clinical usage of these devices.
A1.1.3 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.
A2.1.1 This test method covers the procedures for determining the stiffness and strength of connecting elements (clamps) of external skeletal fixators under axial loads and bending moments. Depending on the design of the connector and its use in the overall construct, the connector needs to transmit one or more components of loading (tension, compression, torsion, or bending, or a combination thereof) between the elements it grips (anchorage elements or bridge elements), without itself undergoing either permanent deformation or excessive elasti...
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Designation: F1541 – 02 (Reapproved 2011)
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 (´) 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
1.1 This specification provides a characterization of the
standard. No other units of measurement are included in this
design and mechanical function of external skeletal fixation
standard.
devices (ESFDs), test methods for characterization of ESFD
1.6 The following safety hazards caveat pertains only to the
mechanical properties, and identifies needs for further devel-
test method portions (Annex A2-Annex A6):
opment of test methods and performance criteria.The ultimate
1.7 This standard does not purport to address all of the
goal is to develop a specification, which defines performance
safety concerns, if any, associated with its use. It is the
criteria and methods for measurement of performance-related
responsibility of the user of this standard to establish appro-
mechanicalcharacteristicsofESFDsandtheirfixationtobone.
priate safety and health practices and determine the applica-
It is not the intention of this specification to define levels of
bility of regulatory limitations prior to use.
performance or case-specific clinical performance of the de-
vices, as insufficient knowledge is available to predict the
2. Referenced Documents
consequences of the use of any of these devices in individual
2.1 ASTM Standards:
patients for specific activities of daily living. Furthermore, it is
A938 Test Method for Torsion Testing of Wire
not the intention of this specification to describe or specify
D790 Test Methods for Flexural Properties of Unreinforced
specific designs for ESFDs.
andReinforcedPlasticsandElectricalInsulatingMaterials
1.2 This specification describes ESFDs for surgical fixation
E4 Practices for Force Verification of Testing Machines
of the skeletal system. It provides basic ESFD geometrical
F67 Specification for Unalloyed Titanium, for Surgical
definitions, dimensions, classification, and terminology; mate-
Implant Applications (UNS R50250, UNS R50400, UNS
rial specifications; performance definitions; test methods; and
R50550, UNS R50700)
characteristics determined to be important to the in-vivo
F90 Specification for Wrought Cobalt-20Chromium-
performance of the device.
15Tungsten-10Nickel Alloy for Surgical Implant Applica-
1.3 This specification includes a terminology and classifi-
tions (UNS R30605)
cationannexandfivestandardtestmethodannexesasfollows:
F136 Specification for Wrought Titanium-6Aluminum-
1.3.1 Classification of External Fixators—Annex A1.
4Vanadium ELI (Extra Low Interstitial)Alloy for Surgical
1.3.2 Test Method for External Skeletal Fixator
Implant Applications (UNS R56401)
Connectors—Annex A2.
F138 Specification for Wrought 18Chromium-14Nickel-
1.3.3 Test Method for Determining In-Plane Compressive
2.5Molybdenum Stainless Steel Bar and Wire for Surgical
Properties of Circular Ring or Ring Segment Bridge
Implants (UNS S31673)
Elements—Annex A3.
F366 Specification for Fixation Pins and Wires
1.3.4 Test Method for External Skeletal Fixator Joints—
F543 Specification and Test Methods for Metallic Medical
Annex A4.
Bone Screws
1.3.5 Test Method for External Skeletal Fixator Pin Anchor-
F544 DESIG ATTRIBUTE F0544 HAD NO TITLE IN
age Elements—Annex A5.
SAD_TABLES
1.3.6 Test Method for External Skeletal Fixator
F1058 Specification for Wrought 40Cobalt-20Chromium-
Subassemblies—Annex A6.
16Iron-15Nickel-7Molybdenum Alloy Wire and Strip for
1.3.7 Test Method for External Skeletal Fixator/Constructs
Surgical Implant Applications (UNS R30003 and UNS
Subassemblies—Annex A7.
R30008)
This specification is under the jurisdiction of ASTM Committee F04 on
Medical and Surgical Materials and Devices and is the direct responsibility of
Subcommittee F04.21 on Osteosynthesis. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2011. Published October 2011. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
published as F1541–94. Last previous edition approved in 2007 as F1541–02 Standards volume information, refer to the standard’s Document Summary page on
´1
(2007) . DOI: 10.1520/F1541-02R11. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F1541 – 02 (2011)
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
F1541 – 02 (2011)
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 DESIG ATTRIBUTE F0544 HAD NO TITLE IN
consistent with standard clinical conventions, for example,
SAD_TABLES
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
A1.3.1 ESFDs are in widespread use in orthopedic surgery,
the right-hand rule and, where possible, should be consistent
primarily for applications involving fracture fixation or limb
with standard clinical terminology, for example, right or left
lengthening,orboth.Themechanicaldemandsplacedonthese
lateral bending, flexion, extension, and torsion.
devices often are severe. Clinical success usually depends on
A1.5.5 Abase coordinate system (X, Y, Z) should be affixed
suitablemechanicalintegrationoftheESFDwiththehostbone
to one of the bones or major bone segments bordering the
or limb.
mechanical defect. This bone or bone segment is termed the
A1.3.2 It is important, therefore, to have broadly accepted
base segment, S , and serves as a datum with respect to which
b
terminology and testing standards by which these devices can
pertinent motion(s) of bone segments or fixator elements, or
be described and their mechanical behaviors measured.
both, can be referenced. Depending on context, S may be
b
A1.3.3 Useful terminology and testing standards must take
defined as being on either the proximal or the distal side of a
into account that the modular nature of most ESFDs deliber-
mechanical defect.
ately affords a great deal of clinical latitude in configuring the
A1.5.6 The other bone(s) or bone segment(s) bordering the
assembled fixator.
mechanical defect, whose potential motion(s) with respect to
S is of interest, is termed the mobile segment(s), S.If
b m
A1.4 Significance and Use
necessary, a local right-handed orthogonal coordinate system
A1.4.1 The purpose of this classification is to establish a
(x, y, z) may be embedded within the S (s).
m
consistent terminology system by means of which these ESFD
A1.5.7 Degrees of Freedom:
configurations can be classified. It is anticipated that a com-
Describing the position, or change in position, of S relative
m
panion testing standard using this classification system will
to S requires specifying one or more independent variables.
b
subsequently be developed.
These variables will be termed positional degrees of freedom
(P-DOF).
A1.5 Basis of Classification
A1.5.7.1 Depending on context, this may involve as many
A1.5.1 An assembled ESFD and the bone(s) or bone ana- as six variables (three translation and three orientation).
log(s) to which it is affixed constitute a fixator-bone construct. A1.5.7.2 Also depending on context, P-DOFs may be used
A1.5.1.1 The assembled ESFD itself, apart from the host to describe motions of interest in various magnitude ranges.
bone, is termed the fixator assembly. For example, P-DOFs may be used to describe one or more
F1541 – 02 (2011)
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 pur-
posef
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