ASTM F1831-97

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: F 1831 – 97
Standard Specification for
Cranial Traction Tongs and Halo External Spinal
Immobilization Devices
This standard is issued under the fixed designation F 1831; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This specification covers standards a manufacturer shall 2.1 IEC Standard:
meet in the designing, manufacturing, testing, labeling, and IEC 601-1
documenting of halo and tong external spinal immobilization
3. Terminology
devices, but it is not to be construed as production methods,
quality control techniques, manufacturer’s lot criteria, or clini- 3.1 Definitions of Terms Specific to This Standard:
3.1.1 cranial traction tong—a device providing weighted
cal recommendations.
1.2 This specification represents the best currently available cervical traction to a patient through invasive attachment to the
skull. This traction instrument is indicated for closed reduction
test procedures at this time and is a minimum safety and
performance standard. of a cervical spine injury (that is, fracture or dislocation).
3.1.1.1 adjustable tong—a cranial traction tong that adjusts
1.3 This specification covers only those halo and tong
devices intended for use on humans for therapeutic purposes. for size, pin positioning, or pin pressure.
3.1.1.2 one-piece tong—a rigid, single-piece, semicircular
This specification assumes the user is well-trained in the
procedures and maintenance of halo and tong application and cranial traction tong designed to accommodate a minimum of
two skull pins for mounting the device to the patients head
has the ability to determine if an abnormality is treatable by
these procedures. below the equator.
3.1.2 halo device—an external fixator for cervical stabiliza-
1.4 This specification describes those devices commonly
known as halo external fixation devices and what is known as tion that fastens by invasive means to a patient’s skull, and
maintains the position of the skull in relation to the thoracic
cranial traction tongs.
area of the patient.
1.5 Cranial traction tongs and halo devices are used to
achieve and maintain optimal spinal alignment, in order to 3.1.3 halo ring—the portion of the halo device that fastens
by invasive means to a patient’s skull below the head equator.
enhance fusion and decrease neurological deficit.
1.6 Monitoringtheprogressoftreatmentafterapplicationof 3.1.3.1 closed loop halo ring—a halo ring incorporating a
closed loop anywhere in the design for purposes of structural
these devices is important, this should be done in accordance
with the manufacturer’s recommendation and guidelines per- integrity when the ring is in use. This type of ring has multiple
positioningoptionsfortheselectionofpinsitesandismounted
taining to the specific device.
1.7 The values stated in both inch-pound and SI units are to to the head with multiple skull pins.
3.1.3.2 head equator—the greatest circumference of the
be regarded separately as the standard. The values given in
parentheses are for information only. head in the coronal aspect
3.1.3.3 open loop halo ring—a halo ring with a posterior
1.8 The following precautionary statement pertains only to
the test method portions Sections 10-15 of this specification: opening, such that the part does not incorporate a closed loop
anywhere in the design for structural integrity. This ring has
This standard does not purport to address all of the safety
concerns, if any, associated with its use. It is the responsibility multiple position options for the selection of pin sites and is
mounted to the head with multiple skull pins.
of the user of this standard to establish appropriate safety and
health practices and determine the applicability of regulatory 3.1.4 halo superstructure—a rigid external framework used
to maintain positioning of the skull and cervical spine in
limitations prior to use.
relation to the thoracic and lumbar spine. Connects the halo
ring to halo vest.
ThisspecificationisunderthejurisdictionofASTMCommitteeF-4onMedical
and Surgical Material and Devices and is the direct responsibility of Subcommittee
F04.31 on Neurosurgical Standards. Available from American National Standards Institute, 1430 Broadway, New
Current edition approved Nov. 10, 1997. Published April 1998. York, NY 10018.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F1831–97
3.1.4.1 halo superstructure adjustment mechanisms— com- 6. Magnetic Resonance Imaging Compatibility
ponents that allow adjustment of angles and distances between Requirements
ring and uprights or vest and uprights.
6.1 These halo external fixator and cranial traction tong
3.1.4.2 transverse bar—a rigid horizontal component of the
magneticresonanceimaging(MRI)compatibilityrequirements
halo superstructure. are intended to protect the patient from harm during MRI
imaging procedures.
3.1.4.3 upright bar—a rigid vertical component of the halo
6.2 Manufacturers shall be responsible for testing the MRI
superstructure.
safety and efficacy of the device.
3.1.4.4 vest attachment mechanism—attaches inferiorly to
6.2.1 Test Methods— See Sections 13-15.
the halo superstructure and connects to vest shell, maintains
positioning of the halo superstructure in relation to the vest
7. Mechanical Integrity
shell.
7.1 Thepurposeofthisrequirementistoensuretheuserand
3.1.4.5 vest plate—part of the superstructure attached to the
the patient that the halo external fixator or cranial traction
vest shell to provide a stable mounting point for the vest
tongs, or both, are capable of withstanding the externally
attachment mechanisms.
imposedconditionsnormallyencounteredduringtheusefullife
3.1.5 halo vest—a body-orthosis that serves as a mounting
of the device.
point for the halo and superstructure.
7.2 Cranial Traction Tongs Mechanical integrity:
3.1.5.1 C.P.R. access—mechanism in vest or superstructure
7.2.1 The cranial traction tongs and any of its components
to allow quick access to patient’s chest for cardiopulmonary
must be manufactured from a material that provides suitable
resuscitation (C.P.R.).
rigid support to the skull pins and any other attached compo-
3.1.5.2 vest liner—padding worn inside of halo vest shell
nents including the traction weights.
and against the skin which distributes the pressure of the vest 7.2.2 Cranialtractiontongpinsshallbesufficientlystrongto
shell against the skin.
resist at least two times the normal maximum static loads that
may be encountered during normal wear.
3.1.5.3 vest shell—rigid portion of body orthosis.
7.2.3 The cranial traction tongs and its components shall be
3.1.6 skull pin—a rigid device used to invasively anchor the
resistant to deformation and sufficiently rigid such that pin
halo ring or cranial traction tongs to the skull at selected
position and pressure on the skull can be maintained at
mounting points.
maximum manufacturer’s specified pin pressures.
3.1.6.1 adjustable skull pin—( 1) a pin that is force con-
7.2.4 Adjustable skull pins shall be calibrated with force
trolled by a mechanical mechanism, that is, spring-loaded
indicators.
pressure pin. (2) a solid threaded pin that maintains pressure
7.2.5 Test Method— See Section 10.
and fixation against the skull through application of a cali-
7.3 Halo Skull Pin Mechanical Integrity:
brated torque.
7.3.1 Halo skull pins shall be sufficiently strong to resist at
3.1.6.2 fixed skull pin—a pin that is mounted directly to a
least two times the normal maximum static and dynamic loads
tong structure requiring a drilled skull hole for positioning and
that may be encountered during normal use.
fixation. Pressure is not adjusted directly through the pin.
7.3.2 Test Method— See Section 11.
3.1.7 traction bail (traction hoop)—a device that may be
7.4 Halo Ring Mechanical Integrity:
attached to the halo ring to facilitate the application of
7.4.1 The halo ring shall be manufactured from a material
weighted longitudinal traction.
that provides suitable rigid support to the attached skull pins
and superstructure.
4. Conformance 7.4.2 The halo ring shall be resistant to deformation and
sufficiently rigid such that pin position and pressure on the
4.1 Presently, this specification is voluntary and not by law.
skull can be maintained at maximum manufacturer’s specified
A manufacturer may label a product as conforming to this
pin pressures.
specification only if the product indeed meets all the require-
7.4.3 Test Method— See Section 11.
ments of this specification.
7.5 Halo Superstructure Assemblies Mechanical Integrity:
7.5.1 A new halo external fixator device must be able to
5. Classification
maintain structural integrity under normal physical loading
5.1 Halo External Fixator—Typically a complete system
when the system is fully assembled.
consisting of the halo ring, skull pins, vest and superstructure.
7.5.2 All mechanical components of the superstructure as-
The uniqueness of this system is its ability to provide self-
semblymustmaintainrigidityandfunctionalintegritythrough-
contained cervical stabilization.
out the useful life of the product.
5.2 Cranial Traction Tongs—Either a rigid single-piece, 7.5.3 Test Method— See Section 12.
semicircular device or an adjustable device. Both designs have 7.6 Halo Vest Assembly Mechanical Integrity:
accommodations for at least two skull pins to be mounted to 7.6.1 The halo vest assembly must provide a stable platform
the skull. Typically designed to be fitted over the top of the for rigid attachment of the superstructure.
head and used for weighted cervical reduction or bed traction, 7.6.2 The halo vest must provide an adjustable means of
or both, in the supine (bed restricted) patient. rigid fixation to the upper body of the patient.
F1831–97
8. Performance Requirements the useful life of the product or as indicated by the manufac-
turer’s recommendations.
8.1 The purpose of these requirements is to ensure that a
8.8 Cranial Traction Tongs Performance Requirements:
halo external fixator or cranial tongs shall meet the minimum
8.8.1 All mechanical fixation components will be manufac-
performance requirements as originally designed.The halo and
tongs device requirements should not vary from procedure to tured out of corrosion resistant materials.
procedure provided they are used and maintained according to
8.8.2 All components shall be manufactured out of materi-
the manufacturer’s recommendation.
alscapableofprovidingfunctionalintegrityovertheusefullife
8.2 Halo External Fixator Performance Requirements:
of the device.
8.2.1 All mechanical fixation components will be manufac-
8.8.3 The manufacturer will be responsible to maintain
tured out of corrosion resistant materials.
adequate mechanical test data or equivalent clinical data in
8.2.2 All components shall be manufactured out of materi- regard to the suitability of design, useful life and diagnostic
alscapableofprovidingfunctionalintegrityovertheusefullife
imaging compatibility of the system.
of the device.
8.8.4 The manufacturer will be responsible for supplying
8.2.3 The manufacturer will be responsible to maintain
materials that are sterilizable by the manufacturer’s recom-
adequate mechanical test data or equivalent clinical data in
mended sterilization techniques.
regard to the suitability of design, useful life and diagnostic
8.8.5 The cranial traction tongs must permit attachment of
imaging compatibility of the system.
cables and other necessary hardware.
8.2.4 The manufacturer will be responsible for supplying
8.9 Cranial Traction Tongs Pin Performance Requirements:
materials that are sterilizable by the manufacturer’s recom-
8.9.1 All tong pins must be supplied by the manufacturer
mended sterilization techniques.
with a method of locking.
8.3 Halo Pin Performance Requirements:
8.9.2 Any portion of the tong pin that is in direct contact
8.3.1 All portions of the skull pin that are in constant
with the patient’s skin shall be manufactured from biologically
physical contact with the patient’s skin shall be manufactured
compatible materials.
from biologically compatible material.
8.3.2 All halo skull pins shall be supplied with a method for
9. Disclosures, Labeling, and Documentation
locking the pin in place in the halo ring.
9.1 These requirements are intended to ensure a manufac-
8.4 Halo Ring Performance Requirements—The manufac-
turer’s written dissemination of all necessary information that
turer will be responsible for providing a ring assembly that
allow a user to determine properly a halo external fixator or
allows for the following:
cranial traction tongs (and all of their related accessories)
8.4.1 The halo ring shall be able to easily and rigidly attach
function, application and limitation. These disclosures, label-
to the superstructure.
ing and documentation requirements also ensure clear identi-
8.4.2 The halo ring shall be able to easily accept a minimum
fication of the product and make available all pertinent data a
of four halo skull pins.
user may require. A manufacturer may label his product as
8.5 Halo Superstructure Assembly Performance Require-
conformingtothisstandardonlyiftheproductfulfillsallofthe
ments:
requirements listed in this specification.
8.5.1 The halo vest and superstructure assemblies shall be
9.2 Disclosures—Amanufacturer shall disclose each speci-
able to be easily attached and detached from the halo ring with
fication listed where applicable.
the appropriate tools.
9.2.1 Single Patient Use Statement—A manufacturer of
8.6 Halo Vest Performance Requirements:
halo external fixation systems or cranial traction tongs shall
8.6.1 The vest material shall be trimmable and moldable
provide a warning statement to inform the user that the device
with the appropriate tools to allow the medical personnel to
is guaranteed for single patient use only.
provide suitable adaptability to the various anatomies encoun-
9.2.2 Sterilization— A disclosure statement that states ex-
tered.
actly which items of the halo external fixator and the cranial
8.6.2 The manufacturer will provide suitable vest liner
traction tongs and their accessories can be sterilized and the
materials to maintain a substrate between the vest shell and the
recommended sterilization procedures shall be included with
skin. These lining materials shall be free of any chemicals or
each device.
toxins, or both, that could cause an allergic response in the
9.2.3 Presterilized Components—A disclosure statement
average patient.
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