ASTM F2385-15(2019)

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: F2385 − 15 (Reapproved 2019)
Standard Practice for
Determining Femoral Head Penetration into Acetabular
Components of Total Hip Replacement Using Clinical
Radiographs
This standard is issued under the fixed designation F2385; 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 1.9 The values stated in SI units are to be regarded as the
standard, with the exception of angular measurements, which
1.1 This practice provides guidance for the measurement of
may be reported in either degrees or radians. Additionally,
the relative displacement of the femoral head and acetabular
pixel density may also be reported in imperial units.
component that result from wear and deformation occurring at
the articular interface of a total hip replacement from sequen- 1.10 The use of this standard may involve the operation of
tial clinical radiographs. potentially hazardous radiographic equipment and does not
purport to address the safety precautions associated with
1.2 This practice is primarily intended for use in evaluating
radiography. It is the responsibility of the user of this standard
patients receiving THRs composed of a polyethylene acetabu-
to define and establish appropriate safety practices. The
lar component articulating against a metal or ceramic femoral
standard does not determine the applicability of regulatory
head.
limitations prior to operating radiographic equipment.
1.3 So-called hard-on-hard articulations such as metal-on-
1.11 This standard does not purport to address all of the
metal and ceramic-on-ceramic THRs are not intended to be
safety concerns, if any, associated with its use. It is the
directly addressed.
responsibility of the user of this standard to establish appro-
1.4 This practice will focus on computer-assisted computa-
priate safety, health, and environmental practices and deter-
tional methodologies for measuring relative displacements
mine the applicability of regulatory limitations prior to use.
over time but not to the exclusion of other methodologies.
1.12 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.5 This practice describes methods for conducting a radio-
graphicwear/creepstudyutilizingvariouscomputationalmeth- ization established in the Decision on Principles for the
ods and is not intended to promote or endorse a particular Development of International Standards, Guides and Recom-
method. mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.6 It is not the intent of this practice to provide detailed
instructions in the use of the various computational methods,
2. Referenced Documents
which is contained in the respective user manuals.
2.1 ASTM Standards:
1.7 It is the intent of this practice to enable comparisons of
E177 Practice for Use of the Terms Precision and Bias in
relativedisplacementsoccurringingroupsofpatientsreceiving
ASTM Test Methods
different formulations of bearing materials. It must be
recognized, however, that there are many possible variations in
3. Terminology
the in vivo conditions. A single clinical study may not be
universally representative.
3.1 All radiographic terminology is consistent with the
referenced standards, unless otherwise stated.
1.8 This practice is not intended to be a performance
standard. It is the responsibility of the user of this practice to
3.2 Definitions:
characterizethesafetyandeffectivenessoftheprosthesisunder
3.2.1 radiostereometric analysis (RSA)—a method devel-
evaluation.
oped by Goren Selvik for measuring relative motion between
ThispracticeisunderthejurisdictionofASTMCommitteeF04onMedicaland
Surgical Materials and Devices and is the direct responsibility of Subcommittee
F04.22 on Arthroplasty. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Aug. 15, 2019. Published August 2019. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2004. Last previous edition approved in 2015 as F2385 – 15. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/F2385-15R19. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2385 − 15 (2019)
two parts from clinical radiographs (1). This method utilizes technique uses sequentialA/Pfilms for two-dimensional analy-
in vivo tantalum beads, an external reference cage, and two sis and A/P and lateral sequential films for three-dimensional
x-ray generators which take two exposures simultaneously. analysis (3).
There are several commercially available software/hardware 3.3.3 UmRSA—an RSA software program developed by
packages for RSA analysis. Biomedical Innovations AB in Umea Sweden. It utilizes
sequential radio pairs in order to measure relative displace-
3.2.2 markers—tantalum beads 1.0 mm, 0.8 mm, or 0.5 mm
ments between two segments or a point relative to a segment.
in diameter.
It utilizes a model based edge matching method for determin-
3.2.2.1 implant markers—in vivo markers placed on the
ing the center of the markers (4).
implant in order to define the implant as a rigid body.
3.3.4 CMS-RSA—an RSA software program developed at
3.2.2.2 cage markers—tantalum beads held in an external
the University of Leiden, Sweden. It utilizes sequential radio
reference frame used to create a three-dimensional coordinate
pairs in order to measure relative displacements between two
system for measuring relative displacements.
segments (5).
3.2.2.3 segment—a three-dimensional rigid body defined by
4. Significance and Use
a minimum of three markers.
4.1 This practice uses clinical radiographs of the hip joint of
3.2.3 edge detection—method of image analysis used to
a patient that has received a total hip replacement to measure
determine the two-dimensional or three-dimensional center
the combined effect of plastic deformation and wear at the
point of a curved surface. Many computational methods of
articular interface which results in three-dimensional displace-
edge detection exist.
ments of the femoral head into the acetabular component.
3.2.4 coordinate system/axes—three orthogonal axes are
4.2 This practice addresses the validation of the various
defined as follows:
computational methods available for measuring the magnitude
3.2.4.1 origin—the center of the coordinate system is lo-
of creep/wear accruing at the articular surface of THRs.
cated at either the geometric center of the acetabular compo-
4.3 This practice addresses the type of radiographic projec-
nent segment or the center of a circle defined using the edge of
tions needed for an analysis as well as general radiographic
the acetabular component.
parameters needed for obtaining high quality films.
3.2.4.2 X-axis—the positive X-axis is to be directed in the
4.4 This practice addresses the criterion for evaluating
medial direction independent of which hip is to be studied.
clinical radiographs for inclusion in a study.
Some software programs correct the sign of this value but the
user must ensure that the protocol maintains the convention,
4.5 This practice addresses the conversion of radiographic
(that is, which way is the patient facing).
images to the appropriate digital format needed for the various
computer-assisted computational methods.
3.2.4.3 Y-axis—the positive Y-axis is to be fixed in the
superior direction.
5. Validation
3.2.4.4 Z-axis—the positive Z-axis is to be fixed in the
5.1 Aphysical phantom model which is capable of replicat-
posterior direction.
ing the three-dimensional displacement of the femoral head at
3.2.5 radio pair—one set of RSA radiographs which were
magnitudes of displacements that are expected to occur clini-
taken simultaneously.
cally should be used to validate new software programs,
modifications to existing programs, and variations to the
3.3 There are a number of computational methods that can
experimental protocol which may affect the results of the
beusedtomeasurecreep/wearofapolyethylenecomponent.A
measurements. A recent publication describes such a phantom
description of a few of the commonly used current methods is
and its use (6). Figs. 1 and 2 show an example of a model
given. This is not meant to be at the exclusion of other
which can be used for this purpose. For comparative purposes,
methods.
the method described by Bragdon et al (6) for calculating
3.3.1 Martell method—as this software is informally re-
accuracy and precision can be used. Illustrative values for the
ferred to in reference to its developer Dr. John Martell of
accuracyandprecisionasmeasuredbythismethodarelistedin
Chicago University, is a semi-automated computer technique
the appendix.
using edge detection and the Hough transformation for the
determination of polyethylene wear. This technique uses se-
5.2 To generate data for a precision and bias statement,
quential A/P films for two-dimensional analysis and A/P and
Practice E177 should be followed.
lateral sequential films for three dimensional analysis (2).
6. Material
3.3.2 Polywear method—a software program developed by
Dr. Peter Devane of the Wellington School of Medicine, New
6.1 Non-RSA Methods of Obtaining Clinical Radiographs
Zealand is a semi-automated computer technique using edge
for Measuring Femoral Head Penetration:
detection for the determination of polyethylene wear. This
6.1.1 These methods utilize anAnterior/Posterior (A/P) and
across-tablelateralprojectionofthepelvis.TheA/Pprojection
is used for measuring a two-dimensional penetration vector.
The cross-table lateral is used to determine the magnitude and
The boldface numbers in parentheses refer to the list of references at the end of
this standard. direction of the three-dimensional penetration vector.
F2385 − 15 (2019)
6.1.4.1 A typical radiographic setup would have a source-
to-plate distance of 101.6 cm (40 in.) and an exposure setting
of 80 kV 25-30 mA-s.
6.1.5 Some non-RSA methods have been validated for the
use of ninety degree standing oblique radiographs of the hip.
6.1.5.1 Amethodofaccuratelyandreproduciblypositioning
the patient for forty five degree oblique projections is needed.
One method, using a positioning chariot, has been described.
Other methods could be employed for this purpose.
6.1.5.2 A typical radiographic setup would have a source-
to-plate distance of 101.6 cm (40 in.) and an exposure setting
of 85 kV 40-50 mA-s.
6.2 RSA Method of Obtaining Clinical Radiographs for
Measuring Femoral Head Penetration:
6.2.1 These radiographs can be taken in the supine or
standing position. The method must be consistent throughout
the subsequent examinations.
6.2.2 The radiographic setup for RSAanalysis
...