ASTM F1831-17

Standard Specification for Cranial Traction Tongs and Halo External Spinal Immobilization Devices

ABSTRACT
This specification covers the minimum safety and performance standards that a manufacturer should meet with regards to the design, manufacture, testing, labeling, and documentation of cranial traction tongs and halo external spinal immobilization devices intended for use on humans for therapeutic purposes. It is, however, not to be construed as production methods, quality control techniques, manufacturer's lot criteria, or clinical recommendations for such. Requirements to which the devices shall be tested on and conform accordingly to are magnetic resonance imaging (MRI) compatibility, mechanical integrity, design performance, induced current flow, and current induced heating.
SCOPE
1.1 This specification covers standards a manufacturer shall meet in the designing, manufacturing, testing, labeling, and documenting of halo and tong external spinal immobilization devices, but it is not to be construed as production methods, quality control techniques, manufacturer's lot criteria, or clinical recommendations.  
1.2 This specification represents the best currently available test procedures at this time and is a minimum safety and performance standard.  
1.3 This specification covers only those halo and tong devices intended for use on humans for therapeutic purposes. This specification assumes the user is well-trained in the procedures and maintenance of halo and tong application and has the ability to determine if an abnormality is treatable by these procedures.  
1.4 This specification describes those devices commonly known as halo external fixation devices and what is known as cranial traction tongs.  
1.5 Cranial traction tongs and halo devices are used to achieve and maintain optimal spinal alignment, in order to enhance fusion and decrease neurological deficit.  
1.6 Monitoring the progress of treatment after application of these devices is important, this should be done in accordance with the manufacturer's recommendation and guidelines pertaining to the specific device.  
1.7 The values stated in both inch-pound and SI units are to be regarded separately as the standard. The values given in parentheses are for information only.  
1.8 The following precautionary statement pertains only to the test method portions, Sections 10 – 13:  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.  
1.9 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-May-2017
• ICS: 11.040.40 - Implants for surgery, prosthetics and orthotics
• Technical Committee: F04 - Medical and Surgical Materials and Devices
• Drafting Committee: F04.31 - Neurosurgical Standards

Relations

• Replaces: ASTM F1831-97(2014) - Standard Specification for Cranial Traction Tongs and Halo External Spinal Immobilization Devices
• Effective Date: 01-Jun-2017
• Refers: ASTM F2503-23e1 - Standard Practice for Marking Medical Devices and Other Items for Safety in the Magnetic Resonance Environment
• Effective Date: 01-Apr-2023
• Refers: ASTM F2182-19 - Standard Test Method for Measurement of Radio Frequency Induced Heating On or Near Passive Implants During Magnetic Resonance Imaging
• Effective Date: 15-Sep-2019
• Refers: ASTM F2182-19e1 - Standard Test Method for Measurement of Radio Frequency Induced Heating On or Near Passive Implants During Magnetic Resonance Imaging
• Effective Date: 15-Sep-2019
• Refers: ASTM F2182-19e2 - Standard Test Method for Measurement of Radio Frequency Induced Heating On or Near Passive Implants During Magnetic Resonance Imaging
• Effective Date: 15-Sep-2019
• Refers: ASTM F2213-17 - Standard Test Method for Measurement of Magnetically Induced Torque on Medical Devices in the Magnetic Resonance Environment
• Effective Date: 01-Sep-2017
• Refers: ASTM F2052-14 - Standard Test Method for Measurement of Magnetically Induced Displacement Force on Medical Devices in the Magnetic Resonance Environment
• Effective Date: 15-May-2014
• Refers: ASTM F2503-13 - Standard Practice for Marking Medical Devices and Other Items for Safety in the Magnetic Resonance Environment
• Effective Date: 01-Jun-2013
• Refers: ASTM F2213-06(2011) - Standard Test Method for Measurement of Magnetically Induced Torque on Medical Devices in the Magnetic Resonance Environment
• Effective Date: 01-Oct-2011
• Refers: ASTM F2182-11a - Standard Test Method for Measurement of Radio Frequency Induced Heating On or Near Passive Implants During Magnetic Resonance Imaging
• Effective Date: 15-Apr-2011
• Refers: ASTM F2182-11 - Standard Test Method for Measurement of Radio Frequency Induced Heating Near Passive Implants During Magnetic Resonance Imaging
• Effective Date: 01-Mar-2011
• Refers: ASTM F2182-09 - Standard Test Method for Measurement of Radio Frequency Induced Heating Near Passive Implants During Magnetic Resonance Imaging
• Effective Date: 15-Nov-2009
• Refers: ASTM F2503-08 - Standard Practice for Marking Medical Devices and Other Items for Safety in the Magnetic Resonance Environment
• Effective Date: 01-Oct-2008
• Refers: ASTM F2119-07 - Standard Test Method for Evaluation of MR Image Artifacts from Passive Implants
• Effective Date: 01-Sep-2007
• Refers: ASTM F2213-06 - Standard Test Method for Measurement of Magnetically Induced Torque on Medical Devices in the Magnetic Resonance Environment
• Effective Date: 01-May-2006

Overview

ASTM F1831-17 is an international standard developed by ASTM International that defines the minimum safety and performance requirements for cranial traction tongs and halo external spinal immobilization devices used in therapeutic settings for humans. The standard specifies criteria that manufacturers must meet regarding design, manufacturing, testing, labeling, and accompanying documentation for these critical neurosurgical devices. However, it is not intended to dictate manufacturing methods, quality control protocols, or provide clinical guidance. Compliance with this standard is key for device safety, reliability, and regulatory acceptance.

Key Topics

• Device Scope and Purpose

  • Covers only cranial traction tongs and halo external spinal immobilization devices designed to achieve and maintain optimal spinal alignment for therapeutic purposes.
  • Suitable for use by trained medical professionals for applications such as spine fracture stabilization and alignment maintenance.

• Design and Mechanical Integrity

  • Requires that all components, including tongs, halo rings, superstructures, vests, and skull pins, are fabricated from durable, rigid, and biocompatible materials.
  • Devices must withstand at least twice the normal maximum clinical loads without permanent deformation or loss of function.

• Performance Requirements

  • Emphasizes corrosion resistance, longevity, and ability to be sterilized by recommended protocols.
  • All fixation and adjustment mechanisms must be reliable for the duration of use.

• MRI Compatibility

  • Devices must be tested for safety and effectiveness in magnetic resonance imaging (MRI) environments, minimizing hazards from induced currents or displacement.

• Labeling and Documentation

  • Product labeling must include identification (model, serial/lot number, manufacturer), imaging compatibility, and C.P.R. access indicators.
  • Instruction manuals must provide clear details on sizing, application, maximum safe loading, care, sterilization protocols, and imaging compatibility.

Applications

• Therapeutic Immobilization

  • Used primarily in hospitals, trauma centers, and rehabilitation facilities for the management of cervical spine injuries, stabilization following spinal fractures, and to promote healing and reduce neurological risk.

• Pre-Surgical/Post-Surgical Support

  • Provides external stabilization pre- and post-operatively to maintain spinal alignment.

• Diagnostic Imaging

  • Ensures device compatibility with MRI and other imaging modalities, critical for ongoing patient assessment and follow-up without device removal.

• Emergency Access

  • Halo vests designed under this specification incorporate features to allow rapid chest access for resuscitation procedures (e.g., C.P.R.).

Related Standards

The standard references several other ASTM and IEC standards essential for ensuring device quality and safety:

• ASTM F2052 - Test Method for Measurement of Magnetically Induced Displacement Force on Medical Devices in MR Environment
• ASTM F2119 - Evaluation of MR Image Artifacts from Passive Implants
• ASTM F2182 - Measurement of RF Induced Heating on or Near Passive Implants During MRI
• ASTM F2213 - Measurement of Magnetically Induced Torque on Medical Devices in MRI
• ASTM F2503 - Practice for Marking Medical Devices for Safety in MRI Environments
• IEC 601-1 - Medical Electrical Equipment Standard

Practical Value

Compliance with ASTM F1831-17 ensures:

• Patient Safety: Devices conform to rigorous mechanical, biological, and imaging safety criteria, minimizing risk of device failure or adverse tissue reactions.
• Reliability for Clinicians: Standardized performance and clear documentation facilitate proper device usage and patient care.
• Regulatory Acceptance: Adherence aids manufacturers in regulatory submissions and market acceptance by demonstrating thorough safety and performance validation.
• Interdisciplinary Compatibility: Clear labeling and documentation support interdisciplinary patient care including surgery, imaging, and emergency medicine.

For manufacturers, healthcare providers, and purchasing decision-makers, referencing ASTM F1831-17 demonstrates a commitment to internationally recognized best practices in the design, deployment, and management of cranial traction tongs and halo external spinal immobilization devices.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F1831 −17
Standard Specification for
Cranial Traction Tongs and Halo External Spinal
Immobilization Devices
This standard is issued under the fixed designation F1831; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope* standard to establish appropriate safety and health practices
and determine the applicability of regulatory limitations prior
1.1 This specification covers standards a manufacturer shall
to use.
meet in the designing, manufacturing, testing, labeling, and
1.9 This international standard was developed in accor-
documenting of halo and tong external spinal immobilization
dance with internationally recognized principles on standard-
devices, but it is not to be construed as production methods,
ization established in the Decision on Principles for the
quality control techniques, manufacturer’s lot criteria, or clini-
Development of International Standards, Guides and Recom-
cal recommendations.
mendations issued by the World Trade Organization Technical
1.2 This specification represents the best currently available
Barriers to Trade (TBT) Committee.
test procedures at this time and is a minimum safety and
performance standard.
2. Referenced Documents
1.3 This specification covers only those halo and tong 2.1 ASTM Standards:
devices intended for use on humans for therapeutic purposes.
F2052 Test Method for Measurement of Magnetically In-
This specification assumes the user is well-trained in the duced Displacement Force on Medical Devices in the
procedures and maintenance of halo and tong application and
Magnetic Resonance Environment
has the ability to determine if an abnormality is treatable by F2119 Test Method for Evaluation of MR Image Artifacts
these procedures.
from Passive Implants
F2182 Test Method for Measurement of Radio Frequency
1.4 This specification describes those devices commonly
Induced Heating On or Near Passive Implants During
known as halo external fixation devices and what is known as
Magnetic Resonance Imaging
cranial traction tongs.
F2213 Test Method for Measurement of Magnetically In-
1.5 Cranial traction tongs and halo devices are used to
duced Torque on Medical Devices in the Magnetic Reso-
achieve and maintain optimal spinal alignment, in order to
nance Environment
enhance fusion and decrease neurological deficit.
F2503 Practice for Marking Medical Devices and Other
1.6 Monitoringtheprogressoftreatmentafterapplicationof
Items for Safety in the Magnetic Resonance Environment
these devices is important, this should be done in accordance
2.2 IEC Standard:
with the manufacturer’s recommendation and guidelines per-
IEC 601-1 Medical Electrical Equipment
taining to the specific device.
3. Terminology
1.7 The values stated in both inch-pound and SI units are to
3.1 Definitions of Terms Specific to This Standard:
be regarded separately as the standard. The values given in
3.1.1 cranial traction tong—a device providing weighted
parentheses are for information only.
cervical traction to a patient through invasive attachment to the
1.8 The following precautionary statement pertains only to
skull. This traction instrument is indicated for closed reduction
the test method portions, Sections10–13: This standard does
of a cervical spine injury (that is, fracture or dislocation).
not purport to address all of the safety concerns, if any,
3.1.1.1 adjustable tong—a cranial traction tong that adjusts
associated with its use. It is the responsibility of the user of this
for size, pin positioning, or pin pressure.
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 F04.31 on Neurosurgical Standards. Standards volume information, refer to the standard’s Document Summary page on
CurrenteditionapprovedJune1,2017.PublishedJuly2017.Originallyapproved the ASTM website.
in 1997. Last previous edition approved in 2014 as F1831 – 97(2014). DOI: Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
10.1520/F1831-17. 4th Floor, New York, NY 10036, http://www.ansi.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1831 − 17
3.1.1.2 one-piece tong—a rigid, single-piece, semicircular pressure pin. (2) a solid threaded pin that maintains pressure
cranial traction tong designed to accommodate a minimum of and fixation against the skull through application of a cali-
two skull pins for mounting the device to the patients head brated torque.
below the equator.
3.1.6.2 fixed skull pin—a pin that is mounted directly to a
3.1.2 halo device—an external fixator for cervical stabiliza- tong structure requiring a drilled skull hole for positioning and
tion that fastens by invasive means to a patient’s skull, and fixation. Pressure is not adjusted directly through the pin.
maintains the position of the skull in relation to the thoracic
3.1.7 traction bail (traction hoop)—a device that may be
area of the patient.
attached to the halo ring to facilitate the application of
weighted longitudinal traction.
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.
4. Conformance
3.1.3.1 closed loop halo ring—a halo ring incorporating a
closed loop anywhere in the design for purposes of structural 4.1 Presently, this specification is voluntary and not by law.
integrity when the ring is in use. This type of ring has multiple A manufacturer may label a product as conforming to this
positioningoptionsfortheselectionofpinsitesandismounted specification only if the product indeed meets all the require-
to the head with multiple skull pins. ments of this specification.
3.1.3.2 head equator—the greatest circumference of the
5. Classification
head in the coronal aspect.
5.1 Halo External Fixator—Typically a complete system
3.1.3.3 open loop halo ring—a halo ring with a posterior
consisting of the halo ring, skull pins, vest and superstructure.
opening, such that the part does not incorporate a closed loop
The uniqueness of this system is its ability to provide self-
anywhere in the design for structural integrity. This ring has
contained cervical stabilization.
multiple position options for the selection of pin sites and is
mounted to the head with multiple skull pins.
5.2 Cranial Traction Tongs—Either a rigid single-piece,
semicircular device or an adjustable device. Both designs have
3.1.4 halo superstructure—a rigid external framework used
accommodations for at least two skull pins to be mounted to
to maintain positioning of the skull and cervical spine in
the skull. Typically designed to be fitted over the top of the
relation to the thoracic and lumbar spine. Connects the halo
head and used for weighted cervical reduction or bed traction,
ring to halo vest.
or both, in the supine (bed restricted) patient.
3.1.4.1 halo superstructure adjustment mechanisms—
components that allow adjustment of angles and distances
6. Magnetic Resonance Imaging Compatibility
between ring and uprights or vest and uprights.
Requirements
3.1.4.2 transverse bar—a rigid horizontal component of the
6.1 These halo external fixator and cranial traction tong
halo superstructure.
magneticresonanceimaging(MRI)compatibilityrequirements
3.1.4.3 upright bar—a rigid vertical component of the halo
are intended to protect the patient from harm during MRI
superstructure.
imaging procedures.
3.1.4.4 vest attachment mechanism—attaches inferiorly to
6.2 Manufacturers shall be responsible for testing the MRI
the halo superstructure and connects to vest shell, maintains
safety and efficacy of the device.
positioning of the halo superstructure in relation to the vest
6.2.1 Test Methods—See Section 13.
shell.
3.1.4.5 vest plate—part of the superstructure attached to the 7. Mechanical Integrity
vest shell to provide a stable mounting point for the vest
7.1 Thepurposeofthisrequirementistoensuretheuserand
attachment mechanisms.
the patient that the halo external fixator or cranial traction
3.1.5 halo vest—a body-orthosis that serves as a mounting
tongs, or both, are capable of withstanding the externally
point for the halo and superstructure.
imposedconditionsnormallyencounteredduringtheusefullife
of the device.
3.1.5.1 C.P.R. access—mechanism in vest or superstructure
to allow quick access to patient’s chest for cardiopulmonary
7.2 Cranial Traction Tongs Mechanical Integrity:
resuscitation (C.P.R.).
7.2.1 The cranial traction tongs and any of its components
must be manufactured from a material that provides suitable
3.1.5.2 vest liner—padding worn inside of halo vest shell
rigid support to the skull pins and any other attached compo-
and against the skin which distributes the pressure of the vest
nents including the traction weights.
shell against the skin.
7.2.2 Cranialtractiontongpinsshallbesufficientlystrongto
3.1.5.3 vest shell—rigid portion of body orthosis.
resist at least two times the normal maximum static loads that
3.1.6 skull pin—a rigid device used to invasively anchor the
may be encountered during normal wear.
halo ring or cranial traction tongs to the skull at selected
7.2.3 The cranial traction tongs and its components shall be
mounting points.
resistant to deformation and sufficiently rigid such that pin
3.1.6.1 adjustable skull pin—(1) a pin that is force con- position and pressure on the skull can be maintained at
trolled by a mechanical mechanism, that is, spring-loaded maximum manufacturer’s specified pin pressures.
F1831 − 17
7.2.4 Adjustable skull pins shall be calibrated with force 8.3.2 All halo skull pins shall be supplied with a method for
indicators. locking the pin in place in the halo ring.
7.2.5 Test Method—See Section 10.
8.4 Halo Ring Performance Requirements—The manufac-
turer will be responsible for providing a ring assembly that
7.3 Halo Skull Pin Mechanical Integrity:
allows for the following:
7.3.1 Halo skull pins shall be sufficiently strong to resist at
8.4.1 The halo ring shall be able to easily and rigidly attach
least two times the normal maximum static and dynamic loads
to the superstructure.
that may be encountered during normal use.
8.4.2 Thehaloringshallbeabletoeasilyacceptaminimum
7.3.2 Test Method—See Section 11.
of four halo skull pins.
7.4 Halo Ring Mechanical Integrity:
8.5 Halo Superstructure Assembly Performance Require-
7.4.1 The halo ring shall be manufactured from a material
ments:
that provides suitable rigid support to the attached skull pins
8.5.1 The halo vest and superstructure assemblies shall be
and superstructure.
able to be easily attached and detached from the halo ring with
7.4.2 The halo ring shall be resistant to deformation and
the appropriate tools.
sufficiently rigid such that pin position and pressure on the
skull can be maintained at maximum manufacturer’s specified
8.6 Halo Vest Performance Requirements:
pin pressures.
8.6.1 The vest material shall be trimmable and moldable
7.4.3 Test Method—See Section 11.
with the appropriate tools to allow the medical personnel to
provide suitable adaptability to the various anatomies encoun-
7.5 Halo Superstructure Assemblies Mechanical Integrity:
tered.
7.5.1 A new halo external fixator device must be able to
8.6.2 The manufacturer will provide suitable vest liner
maintain structural integrity under normal physical loading
materials to maintain a substrate between the vest shell and the
when the system is fully assembled.
skin. These lining materials shall be free of any chemicals or
7.5.2 All mechanical components of the superstructure as-
toxins, or both, that could cause an allergic response in the
semblymustmaintainrigidityandfunctionalintegritythrough-
average patient.
out the useful life of the product.
8.6.3 The halo vest shall have a vest attachment mechanism
7.5.3 Test Method—See Section 12.
whereby the halo superstructure is suitably attached via the
7.6 Halo Vest Assembly Mechanical Integrity:
appropriate tools or mechanism.
7.6.1 The halo vest assembly must provide a stable platform
8.6.4 The halo vest shall allow rapid and complete access to
for rigid attachment of the superstructure.
the chest in the event of a cardiac emergency to allow access to
7.6.2 The halo vest must provide an adjustable means of
the chest for C.P.R.
rigid fixation to the upper body of the patient.
8.7 Halo Tools Performance Requirements—All halo ad-
justment tools supplied by the manufacturer shall consistently
8. Performance Requirements
perform in the manner to which they were designed throughout
8.1 The purpose of these requirements is to ensure that a the useful life of the product or as indicated by the manufac-
halo external fixator or cranial tongs shall meet the minimum
turer’s recommendations.
performance requirements as originally designed.The halo and
8.8 Cranial Traction Tongs Performance Requirements:
tongs device requirements should not vary from procedure to
8.8.1 All mechanical fixation components will be manufac-
procedure provided they are used and maintained according to
tured out of corrosion resistant materials.
the manufacturer’s recommendation.
8.8.2 All components shall be manufactured out of materi-
8.2 Halo External Fixator Performance Requirements:
alscapableofprovidingfunctionalintegrityovertheusefullife
8.2.1 All mechanical fixation components will be manufac-
of the device.
tured out of corrosion resistant materials.
8.8.3 The manufacturer will be responsible to maintain
8.2.2 All components shall be manufactured out of materi- adequate mechanical test data or equivalent clinical data in
alscapableofprovidingfunctionalintegrityovertheusefullife regard to the suitability of design, useful life and diagnostic
of the device. imaging compatibility of the system.
8.2.3 The manufacturer will be responsible to maintain 8.8.4 The manufacturer will be responsible for supplying
adequate mechanical test data or equivalent clinical data in materials that are sterilizable by the manufacturer’s recom-
regard to the suitability of design, useful life and diagnostic mended sterilization techniques.
imaging compatibility of the system. 8.8.5 The cranial traction tongs must permit attachment of
8.2.4 The manufacturer will be responsible for supplying cables and other necessary hardware.
materials that are sterilizable by the manufacturer’s recom-
8.9 Cranial Traction Tongs Pin Performance Requirements:
mended sterilization techniques.
8.9.1 All tong pins must be supplied by the manufacturer
8.3 Halo Pin Performance Requirements: with a method of locking.
8.3.1 All portions of the skull pin that are in constant 8.9.2 Any portion of the tong pin that is in direct contact
physical contact with the patient’s skin shall be manufactured with the patient’s skin shall be manufactured from biologically
from biologically compatible material. compatible materials.
F1831 − 17
9. Disclosures, Labeling, and Documentation 9.4.2.5 Cleaning instructions,
9.4.2.6 Patient care guidelines,
9.1 These requirements are intended to ensure a manufac-
9.4.2.7 Diagnostic imaging compatibility guidelines, and
turer’s written dissemination of all necessary information that
9.4.2.8 Manufacturer or distributor’s name and address, or
allow a user to determine properly a halo external fixator or
both.
cranial traction tongs (and all of their related accessories)
function, application and limitation. These disclosures, label-
10. Test Method for Mechanical Integrity of Cranial
ing and documentation requirements also ensure clear identi-
Traction Tongs
fication of the product and make available all pertinent data a
user may require. A manufacturer may label his product as 10.1 Scope—This test method covers the mechanical integ-
conformingtothisstandardonlyiftheproductfulfillsallofthe rity of tongs with skull pins and their ability to withstand a
requirements listed in this specification. loading without significant loss of function.
10.1.1 Summary of Test Method—The tongs are set up such
9.2 Disclosures—A manufacturer shall disclose each speci-
that the loading is applied at the point on the tongs as it would
fication listed where applicable.
beundernormaluseasrecommendedbythemanufacturer.The
9.2.1 Single Patient Use Statement—Amanufacturerofhalo
tongs are supported as described in 10.1.3 and 10.1.3.1. The
external fixation systems or cranial traction tongs shall provide
amount of deflection and ability of the device to withstand the
a warning statement to inform the user that the device is
loading is recorded.
guaranteed for single patient use only.
10.1.2 Significance and Use—For safety reasons, the device
9.2.2 Sterilization—A disclosure statement that states ex-
shall be designed to withstand a minimum of twice the
actly which items of the halo external fixator and the cranial
maximumloadtypicallyusedduringnormalshort-termclinical
traction tongs and their accessories can be sterilized and the
applicationsorasoutlinedbythemanufacturerintheproduct’s
recommended sterilization procedures shall be included with
instruction manuals without adverse deflection of any compo-
each device.
nents of the device.
9.2.3 Presterilized Components—A disclosure statement
10.1.3 Apparatus—Tongs shall be suspended, utilizing any
shall be included with each presterilized component of either
attachment devices supplied with the product by the manufac-
thehaloorthetongs.Thisstatementshallincludethefollowing
turer as shown in Fig. 1. Skull pins shall be inserted into the
information: the device is sterile, the expiration date, notes of
unit and inserted into an aluminum mounting block such that
caution concerning means of shipping, storage and use of the
any load applied to the tong will be carried equally by all skull
instrument, and lot and batch information.
pinsandattachmentpointsandsothattheresultantloadwillbe
9.2.4 Imaging Compatibility—Manufactures shall be re-
applied axially so as not to apply any angular force to the arms
sponsible for labeling the product according to imaging com-
of the tongs and in such a way that any load applied to the
patibility to avoid confusion by the end user.
tongs will be carried equally by all attachment points.
9.3 Labeling:
10.1.3.1 Aluminum Skull Pin Mount—An aluminum block
9.3.1 All required labeling shall be legible in terms of size
shall be predrilled to a maximum depth of 2 mm to accommo-
and color as dictated by FDA guidelines (21 CFR 820). The
date the tips of the skull pins.
labeling must also be durable to last the life of the product and
10.1.3.2 The test specimen shall consist of the manufactur-
permanently attached so as not to be lost.
er’s new, finished, untested product.
9.3.2 All halo external fixators and cranial traction tongs
10.1.4 Procedure:
shall be labeled so as to contain the following information:
10.1.4.1 If the tongs are adjustable, they shall be set in an
9.3.2.1 Model number and size,
averageortypicalpositionofuseforaheadwithalateralwidth
9.3.2.2 Manufacturer or distributor name, or both,
of 17 cm, or to the median position within the range the device
9.3.2.3 Serial number or lot and batch number,
is designed to accommodate.
9.3.2.4 Diagnostic imaging compatibility indicators, and
10.1.4.2 Insert the skull pins into the predrilled holes in the
9.3.2.5 C.P.R. access indicators.
aluminum block and tighten them according to manufacturer’s
9.3.3 If labeling is not conducive to direct attachment to the recommendations for optimum force.
device then all information shall be provided in the manufac-
turer’s instruction manual or on the final packaging.
9.4 Documentation:
9.4.1 All halos and tongs shall include instruction manuals.
9.4.2 All instruction manuals shall contain the following
information when applicable:
9.4.2.1 Recommended sizing and application instructions
9.4.2.2 Recommended safe maximum traction loading in-
formation for the ring and traction bail or cranial traction tong
as the composite system (ring and pins) excluding physiologi-
cal parameters associated with the patient’s skull.
9.4.2.3 CPR access instructions,
9.4.2.4 Recommended pin torque settings, FIG. 1 Suspended Tongs
F1831 − 17
10.1.4.3 Applyaloadtothedevicewhereskeletaltractionis 10.2.5.2 Insert the skull pins into the predrilled holes in the
applied in a clinical setting per the manufacturer’s instructions. aluminum block and tighten them according to manufacturer’s
The load may be applied incrementally (maximum 10 lb (g) recommendations for optimum force.
increments) or continuously at a maximum rate of 0.127 10.2.5.3 Applyaloadtothedevicewhereskeletaltractionis
cm/min.
applied in a clinical setting in accordance with the manufac-
turer’s instructions. The load may be applied incrementally
10.1.4.4 Load the device to either 100 kg or twice the
maximum safe load recommended by the manufacturer. (maximum 10
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: F1831 − 97 (Reapproved 2014) F1831 − 17
Standard Specification for
Cranial Traction Tongs and Halo External Spinal
Immobilization Devices
This standard is issued under the fixed designation F1831; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope Scope*
1.1 This specification covers standards a manufacturer shall meet in the designing, manufacturing, testing, labeling, and
documenting of halo and tong external spinal immobilization devices, but it is not to be construed as production methods, quality
control techniques, manufacturer’s lot criteria, or clinical recommendations.
1.2 This specification represents the best currently available test procedures at this time and is a minimum safety and
performance standard.
1.3 This specification covers only those halo and tong devices intended for use on humans for therapeutic purposes. This
specification assumes the user is well-trained in the procedures and maintenance of halo and tong application and has the ability
to determine if an abnormality is treatable by these procedures.
1.4 This specification describes those devices commonly known as halo external fixation devices and what is known as cranial
traction tongs.
1.5 Cranial traction tongs and halo devices are used to achieve and maintain optimal spinal alignment, in order to enhance fusion
and decrease neurological deficit.
1.6 Monitoring the progress of treatment after application of these devices is important, this should be done in accordance with
the manufacturer’s recommendation and guidelines pertaining to the specific device.
1.7 The values stated in both inch-pound and SI units are to be regarded separately as the standard. The values given in
parentheses are for information only.
1.8 The following precautionary statement pertains only to the test method portions, Sections 10 – 1315 of this specification-
::This 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.
1.9 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
F2052 Test Method for Measurement of Magnetically Induced Displacement Force on Medical Devices in the Magnetic
Resonance Environment
F2119 Test Method for Evaluation of MR Image Artifacts from Passive Implants
F2182 Test Method for Measurement of Radio Frequency Induced Heating On or Near Passive Implants During Magnetic
Resonance Imaging
F2213 Test Method for Measurement of Magnetically Induced Torque on Medical Devices in the Magnetic Resonance
Environment
This specification is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Devices and is the direct responsibility of Subcommittee
F04.31 on Neurosurgical Standards.
Current edition approved Oct. 1, 2014June 1, 2017. Published November 2014July 2017. Originally approved in 1997. Last previous edition approved in 20062014 as
F1831 – 97(2006).97(2014). DOI: 10.1520/F1831-97R14.10.1520/F1831-17.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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F2503 Practice for Marking Medical Devices and Other Items for Safety in the Magnetic Resonance Environment
2.2 IEC Standard:
IEC 601-1 Medical Electrical Equipment
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 cranial traction tong—a device providing weighted cervical traction to a patient through invasive attachment to the skull.
This traction instrument is indicated for closed reduction of a cervical spine injury (that is, fracture or dislocation).
3.1.1.1 adjustable tong—a cranial traction tong that adjusts for size, pin positioning, or pin pressure.
3.1.1.2 one-piece tong—a rigid, single-piece, semicircular cranial traction tong designed to accommodate a minimum of two
skull pins for mounting the device to the patients head below the equator.
3.1.2 halo device—an external fixator for cervical stabilization that fastens by invasive means to a patient’s skull, and maintains
the position of the skull in relation to the thoracic area of the patient.
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.
3.1.3.1 closed loop halo ring—a halo ring incorporating a closed loop anywhere in the design for purposes of structural integrity
when the ring is in use. This type of ring has multiple positioning options for the selection of pin sites and is mounted to the head
with multiple skull pins.
3.1.3.2 head equator—the greatest circumference of the head in the coronal aspect.
3.1.3.3 open loop halo ring—a halo ring with a posterior opening, such that the part does not incorporate a closed loop anywhere
in the design for structural integrity. This ring has multiple position options for the selection of pin sites and is mounted to the head
with multiple skull pins.
3.1.4 halo superstructure—a rigid external framework used to maintain positioning of the skull and cervical spine in relation
to the thoracic and lumbar spine. Connects the halo ring to halo vest.
3.1.4.1 halo superstructure adjustment mechanisms—components that allow adjustment of angles and distances between ring
and uprights or vest and uprights.
3.1.4.2 transverse bar—a rigid horizontal component of the halo superstructure.
3.1.4.3 upright bar—a rigid vertical component of the halo superstructure.
3.1.4.4 vest attachment mechanism—attaches inferiorly to the halo superstructure and connects to vest shell, maintains
positioning of the halo superstructure in relation to the vest shell.
3.1.4.5 vest plate—part of the superstructure attached to the vest shell to provide a stable mounting point for the vest attachment
mechanisms.
3.1.5 halo vest—a body-orthosis that serves as a mounting point for the halo and superstructure.
3.1.5.1 C.P.R. access—mechanism in vest or superstructure to allow quick access to patient’s chest for cardiopulmonary
resuscitation (C.P.R.).
3.1.5.2 vest liner—padding worn inside of halo vest shell and against the skin which distributes the pressure of the vest shell
against the skin.
3.1.5.3 vest shell—rigid portion of body orthosis.
3.1.6 skull pin—a rigid device used to invasively anchor the halo ring or cranial traction tongs to the skull at selected mounting
points.
3.1.6.1 adjustable skull pin—(1) a pin that is force controlled by a mechanical mechanism, that is, spring-loaded pressure pin.
(2) a solid threaded pin that maintains pressure and fixation against the skull through application of a calibrated torque.
3.1.6.2 fixed skull pin—a pin that is mounted directly to a tong structure requiring a drilled skull hole for positioning and
fixation. Pressure is not adjusted directly through the pin.
3.1.7 traction bail (traction hoop)—a device that may be attached to the halo ring to facilitate the application of weighted
longitudinal traction.
4. Conformance
4.1 Presently, this specification is voluntary and not by law. A manufacturer may label a product as conforming to this
specification only if the product indeed meets all the requirements of this specification.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
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5. Classification
5.1 Halo External Fixator—Typically a complete system consisting of the halo ring, skull pins, vest and superstructure. The
uniqueness of this system is its ability to provide self-contained cervical stabilization.
5.2 Cranial Traction Tongs—Either a rigid single-piece, semicircular device or an adjustable device. Both designs have
accommodations for at least two skull pins to be mounted to the skull. Typically designed to be fitted over the top of the head and
used for weighted cervical reduction or bed traction, or both, in the supine (bed restricted) patient.
6. Magnetic Resonance Imaging Compatibility Requirements
6.1 These halo external fixator and cranial traction tong magnetic resonance imaging (MRI) compatibility requirements are
intended to protect the patient from harm during MRI imaging procedures.
6.2 Manufacturers shall be responsible for testing the MRI safety and efficacy of the device.
6.2.1 Test Methods—See SectionsSection 13 – 1513.
7. Mechanical Integrity
7.1 The purpose of this requirement is to ensure the user and the patient that the halo external fixator or cranial traction tongs,
or both, are capable of withstanding the externally imposed conditions normally encountered during the useful life of the device.
7.2 Cranial Traction Tongs Mechanical Integrity:
7.2.1 The cranial traction tongs and any of its components must be manufactured from a material that provides suitable rigid
support to the skull pins and any other attached components including the traction weights.
7.2.2 Cranial traction tong pins shall be sufficiently strong to resist at least two times the normal maximum static loads that may
be encountered during normal wear.
7.2.3 The cranial traction tongs and its components shall be resistant to deformation and sufficiently rigid such that pin position
and pressure on the skull can be maintained at maximum manufacturer’s specified pin pressures.
7.2.4 Adjustable skull pins shall be calibrated with force indicators.
7.2.5 Test Method—See Section 10.
7.3 Halo Skull Pin Mechanical Integrity:
7.3.1 Halo skull pins shall be sufficiently strong to resist at least two times the normal maximum static and dynamic loads that
may be encountered during normal use.
7.3.2 Test Method—See Section 11.
7.4 Halo Ring Mechanical Integrity:
7.4.1 The halo ring shall be manufactured from a material that provides suitable rigid support to the attached skull pins and
superstructure.
7.4.2 The halo ring shall be resistant to deformation and sufficiently rigid such that pin position and pressure on the skull can
be maintained at maximum manufacturer’s specified pin pressures.
7.4.3 Test Method—See Section 11.
7.5 Halo Superstructure Assemblies Mechanical Integrity:
7.5.1 A new halo external fixator device must be able to maintain structural integrity under normal physical loading when the
system is fully assembled.
7.5.2 All mechanical components of the superstructure assembly must maintain rigidity and functional integrity throughout the
useful life of the product.
7.5.3 Test Method—See Section 12.
7.6 Halo Vest Assembly Mechanical Integrity:
7.6.1 The halo vest assembly must provide a stable platform for rigid attachment of the superstructure.
7.6.2 The halo vest must provide an adjustable means of rigid fixation to the upper body of the patient.
8. Performance Requirements
8.1 The purpose of these requirements is to ensure that a halo external fixator or cranial tongs shall meet the minimum
performance requirements as originally designed. The halo and tongs device requirements should not vary from procedure to
procedure provided they are used and maintained according to the manufacturer’s recommendation.
8.2 Halo External Fixator Performance Requirements:
8.2.1 All mechanical fixation components will be manufactured out of corrosion resistant materials.
8.2.2 All components shall be manufactured out of materials capable of providing functional integrity over the useful life of the
device.
8.2.3 The manufacturer will be responsible to maintain adequate mechanical test data or equivalent clinical data in regard to
the suitability of design, useful life and diagnostic imaging compatibility of the system.
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8.2.4 The manufacturer will be responsible for supplying materials that are sterilizable by the manufacturer’s recommended
sterilization techniques.
8.3 Halo Pin Performance Requirements:
8.3.1 All portions of the skull pin that are in constant physical contact with the patient’s skin shall be manufactured from
biologically compatible material.
8.3.2 All halo skull pins shall be supplied with a method for locking the pin in place in the halo ring.
8.4 Halo Ring Performance Requirements—The manufacturer will be responsible for providing a ring assembly that allows for
the following:
8.4.1 The halo ring shall be able to easily and rigidly attach to the superstructure.
8.4.2 The halo ring shall be able to easily accept a minimum of four halo skull pins.
8.5 Halo Superstructure Assembly Performance Requirements:
8.5.1 The halo vest and superstructure assemblies shall be able to be easily attached and detached from the halo ring with the
appropriate tools.
8.6 Halo Vest Performance Requirements:
8.6.1 The vest material shall be trimmable and moldable with the appropriate tools to allow the medical personnel to provide
suitable adaptability to the various anatomies encountered.
8.6.2 The manufacturer will provide suitable vest liner materials to maintain a substrate between the vest shell and the skin.
These lining materials shall be free of any chemicals or toxins, or both, that could cause an allergic response in the average patient.
8.6.3 The halo vest shall have a vest attachment mechanism whereby the halo superstructure is suitably attached via the
appropriate tools or mechanism.
8.6.4 The halo vest shall allow rapid and complete access to the chest in the event of a cardiac emergency to allow access to
the chest for C.P.R.
8.7 Halo Tools Performance Requirements—All halo adjustment tools supplied by the manufacturer shall consistently perform
in the manner to which they were designed throughout the useful life of the product or as indicated by the manufacturer’s
recommendations.
8.8 Cranial Traction Tongs Performance Requirements:
8.8.1 All mechanical fixation components will be manufactured out of corrosion resistant materials.
8.8.2 All components shall be manufactured out of materials capable of providing functional integrity over the useful life of the
device.
8.8.3 The manufacturer will be responsible to maintain adequate mechanical test data or equivalent clinical data in regard to
the suitability of design, useful life and diagnostic imaging compatibility of the system.
8.8.4 The manufacturer will be responsible for supplying materials that are sterilizable by the manufacturer’s recommended
sterilization techniques.
8.8.5 The cranial traction tongs must permit attachment of cables and other necessary hardware.
8.9 Cranial Traction Tongs Pin Performance Requirements:
8.9.1 All tong pins must be supplied by the manufacturer with a method of locking.
8.9.2 Any portion of the tong pin that is in direct contact with the patient’s skin shall be manufactured from biologically
compatible materials.
9. Disclosures, Labeling, and Documentation
9.1 These requirements are intended to ensure a manufacturer’s written dissemination of all necessary information that allow
a user to determine properly a halo external fixator or cranial traction tongs (and all of their related accessories) function,
application and limitation. These disclosures, labeling and documentation requirements also ensure clear identification of the
product and make available all pertinent data a user may require. A manufacturer may label his product as conforming to this
standard only if the product fulfills all of the requirements listed in this specification.
9.2 Disclosures—A manufacturer shall disclose each specification listed where applicable.
9.2.1 Single Patient Use Statement—A manufacturer of halo external fixation systems or cranial traction tongs shall provide a
warning statement to inform the user that the device is guaranteed for single patient use only.
9.2.2 Sterilization—A disclosure statement that states exactly which items of the halo external fixator and the cranial traction
tongs and their accessories can be sterilized and the recommended sterilization procedures shall be included with each device.
9.2.3 Presterilized Components—A disclosure statement shall be included with each presterilized component of either the halo
or the tongs. This statement shall include the following information: the device is sterile, the expiration date, notes of caution
concerning means of shipping, storage and use of the instrument, and lot and batch information.
9.2.4 Imaging Compatibility—Manufactures shall be responsible for labeling the product according to imaging compatibility to
avoid confusion by the end user.
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9.3 Labeling:
9.3.1 All required labeling shall be legible in terms of size and color as dictated by FDA guidelines (21 CFR 820). The labeling
must also be durable to last the life of the product and permanently attached so as not to be lost.
9.3.2 All halo external fixators and cranial traction tongs shall be labeled so as to contain the following information:
9.3.2.1 Model number and size,
9.3.2.2 Manufacturer or distributor name, or both,
9.3.2.3 Serial number or lot and batch number,
9.3.2.4 Diagnostic imaging compatibility indicators, and
9.3.2.5 C.P.R. access indicators.
9.3.3 If labeling is not conducive to direct attachment to the device then all information shall be provided in the manufacturer’s
instruction manual or on the final packaging.
9.4 Documentation:
9.4.1 All halos and tongs shall include instruction manuals.
9.4.2 All instruction manuals shall contain the following information when applicable:
9.4.2.1 Recommended sizing and application instructions
9.4.2.2 Recommended safe maximum traction loading information for the ring and traction bail or cranial traction tong as the
composite system (ring and pins) excluding physiological parameters associated with the patient’s skull.
9.4.2.3 CPR access instructions,
9.4.2.4 Recommended pin torque settings,
9.4.2.5 Cleaning instructions,
9.4.2.6 Patient care guidelines,
9.4.2.7 Diagnostic imaging compatibility guidelines, and
9.4.2.8 Manufacturer or distributor’s name and address, or both.
10. Test Method for Mechanical Integrity of Cranial Traction Tongs
10.1 Scope—This test method covers the mechanical integrity of tongs with skull pins and their ability to withstand a loading
without significant loss of function.
10.1.1 Summary of Test Method—The tongs are set up such that the loading is applied at the point on the tongs as it would be
under normal use as recommended by the manufacturer. The tongs are supported as described in 10.1.3 and 10.1.3.1. The amount
of deflection and ability of the device to withstand the loading is recorded.
10.1.2 Significance and Use—For safety reasons, the device shall be designed to withstand a minimum of twice the maximum
load typically used during normal short-term clinical applications or as outlined by the manufacturer in the product’s instruction
manuals without adverse deflection of any components of the device.
10.1.3 Apparatus—Tongs shall be suspended, utilizing any attachment devices supplied with the product by the manufacturer
as shown in Fig. 1. Skull pins shall be inserted into the unit and inserted into an aluminum mounting block such that any load
applied to the tong will be carried equally by all skull pins and attachment points and so that the resultant load will be applied
axially so as not to apply any angular force to the arms of the tongs and in such a way that any load applied to the tongs will be
carried equally by all attachment points.
10.1.3.1 Aluminum Skull Pin Mount—An aluminum block shall be predrilled to a maximum depth of 2 mm to accommodate
the tips of the skull pins.
10.1.3.2 The test specimen shall consist of the manufacturer’s new, finished, untested product.
10.1.4 Procedure:
10.1.4.1 If the tongs are adjustable, they shall be set in an average or typical position of use for a head with a lateral width of
17 cm, or to the median position within the range the device is designed to accommodate.
10.1.4.2 Insert the skull pins into the predrilled holes in the aluminum block and tighten them according to manufacturer’s
recommendations for optimum force.
FIG. 1 Suspended Tongs
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10.1.4.3 Apply a load to the device where skeletal traction is applied in a clinical setting per the manufacturer’s instructions.
The load may be applied incrementally (maximum 10 lb (g) increments) or continuously at a maximum rate of 0.127 cm/min.
10.1.4.4 Load the device to either 100 kg or twice the maximum safe load recommended by the manufacturer.
10.1.4.5 After the necessary loading is achieved, leave the apparatus in place for a period of 20 min.
10.1.4.6 Document load versus displacement curves throughout the test.
10.1.4.7 After 20 min, unload the device and document the final displacement of the device in the unloaded state.
10.1.5 Interpretation of Results:
10.1.5.1 Any tong able to maintain the maximum load without signs of plastic deformation in any components of the device
shall have passed the test.
10.1.5.2 Any tong demonstrating plastic deformation in any components of the device after unloading the maximum load shall
have failed the test.
10.2 Additional Test Method for Cranial Traction Tongs:
10.2.1 Scope—This test method covers the mechanical integrity of tongs with skull pins and their ability to withstand loading
without significant loss of function.
10.2.2 Summary of Test Method—The tongs are set up such that the loading is applied at the point on the tongs as it would be
under normal use as recommended by the manufacturer. The tongs are supported as described in 10.2.3 and 10.2.3.1. The amount
of deflection and ability of the device to withstand the loading is recorded.
10.2.3 Significance and Use—For safety reasons, the device shall be designed to withstand a minimum of twice the maximum
load typically used during normal long-term clinical applications or as outlined by the manufacturer in the product’s instruction
manuals without plastic deformation of any component of the device. The rotational and dynamic loading component that occurs
in a clinical setting as a result of turning the patient in bed must also be considered.
10.2.4 Apparatus—Tongs shall be suspended, utilizing any attachment devices supplied with the product by the manufacturer
as shown in Fig. 1. Skull pins shall be inserted into the unit and inserted into an aluminum mounting block such that any load
applied to the tong will be carried equally by all skull pins and attachment points and so that the resultant load will be applied
axially so as not to apply any angular force to the arms of the tong and in such a way that any load applied to the tongs will be
carried equally by all attachment points.
10.2.4.1 Aluminum Skull Pin Mount—An aluminum block shall be predrilled to a maximum depth of 2 mm to accommodate
the insertion of the tips of the skull pins.
10.2.4.2 The test specimen shall consist of the manufacturer’s new, finished, untested product.
10.2.5 Procedure:
10.2.5.1 If the tongs are adjustable, they shall be set in an average or typical position of use for a head with a lateral width of
17 cm, or to the median position within the range the device is designed to accommodate.
10.2.5.2 Insert the skull pins into the predrilled holes in the aluminum block and tighten them according to manufacturer’s
recommendations for optimum force.
10.2.5.3 Apply a load to the device where skeletal traction is applied in a clinical setting in accordance with the manufacturer’s
instructions. The load may be applied incrementally (maximum 10 lb (g) increments) or continuously at a rate not to exceed 0.127
cm/min.
10.2.5.4 Load the device to 60 kgs.
10.2.5.5 After the necessary loading is achieved, leave the apparatus in place for a period of one week. During this time,
alternate loading in increments of approximately 10° from center (+10°, 0°, –10°) once every 24 h to simulate angular traction
forces.
10.2.5.6 After one week, measure and document the change in displacement between the arms of the device from the unloaded
state to the fully loaded state and back to the unloaded state.
10.2.6 Interpretation of Results:
10.2.6.1 Any tong able to maintain the 60 kg load for one week without signs of plastic deformation in any component of the
device shall have passed the test.
10.2.6.2 Any tong demonstrating plastic deformation in any component of the device after unloading the 60 kg load shall have
failed the test.
11. Test Method for Mechanical Integrity of Halo Rings and Attachment Bails
11.1 Scope—This protocol has been developed to test the mechanical integrity of halo rings and their corresponding bails, as
well as their ability to withstand loading without significant loss of function. The equipment used for this test has been designed
to accommodate all known sizes and shapes of halo rings.
11.1.1 Summary of Test Method—The halo rings and traction bails are configured to simulate normal use. Loads are applied at
the points recommended by the manufacturer for normal traction application. The halo rings and traction bails are supported as
described in 11.1.3.
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11.1.2 Significance and Use—For safety reasons, the device shall be designed to withstand a minimum of twice the maximum
load typically used during normal clinical applications or as outlined by the manufacturer in the product’s instruction manuals
without significant elastic deformation and without any plastic deformation. The traction bail must remain intact throughout
testing.
11.1.3 Apparatus—The ring shall be suspended, utilizing any traction attachment components supplied with the product by the
manufacturer as shown in Fig. 2. Skull pins shall be inserted into the r
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