ASTM F2385-04(2010)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: F2385 − 04(Reapproved 2010)
Standard Test Method 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 Thistestmethodprovidesguidanceforthemeasurement
may be reported in either degrees or radians.
of the relative displacement of the femoral head and acetabular
component that result from wear and deformation occurring at 1.10 The use of this standard may involve the operation of
the articular interface of a total hip replacement from sequen- potentially hazardous radiographic equipment and does not
tial clinical radiographs. purport to address the safety precautions associated with
radiography. It is the responsibility of the user of this standard
1.2 This test method is primarily intended for use in
to define and establish appropriate safety practices. The
evaluating patients receiving THRs composed of a polyethyl-
standard does not determine the applicability of regulatory
ene acetabular component articulating against a metal or
limitations prior to operating radiographic equipment.
ceramic femoral head.
1.11 This standard does not purport to address all of the
1.3 So-called hard-on-hard articulations such as metal-on-
safety concerns, if any, associated with its use. It is the
metal and ceramic-on-ceramic THRs are not intended to be
responsibility of the user of this standard to establish appro-
directly addressed.
priate safety and health practices and determine the applica-
1.4 This test method will focus on computer assisted com-
bility of regulatory limitations prior to use.
putational methodologies for measuring relative displacements
over time but not to the exclusion of other methodologies.
2. Referenced Documents
1.5 This test method describes methods for conducting a 2.1 ASTM Standards:
radiographic wear/creep study utilizing various computational
E177 Practice for Use of the Terms Precision and Bias in
methods and is not intended to promote or endorse a particular
ASTM Test Methods
method. E691 Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method
1.6 It is not the intent of this test method to provide detailed
instructions in the use of the various computational methods,
3. Terminology
which is contained in the respective user manuals.
3.1 All radiographic terminology is consistent with the
1.7 It is the intent of this test method to enable comparisons
referenced standards, unless otherwise stated.
of relative displacements occurring in groups of patients
3.2 Definitions:
receiving different formulations of bearing materials. It must
3.2.1 radiostereometric analysis (RSA)—a method devel-
berecognized,however,thattherearemanypossiblevariations
oped by Goren Selvik for measuring relative motion between
in the in vivo conditions. A single clinical study may not be
two parts from clinical radiographs (1). This method utilizes
universally representative.
in vivo tantalum beads, an external reference cage, and two
1.8 This test method is not intended to be a performance
x-ray generators which take two exposures simultaneously.
standard. It is the responsibility of the user of this test method
There are several commercially available software/hardware
to characterize the safety and effectiveness of the prosthesis
packages for RSA analysis.
under evaluation.
1 2
This test method is under the jurisdiction ofASTM Committee F04 on Medical For referenced ASTM standards, visit the ASTM website, www.astm.org, or
and Surgical Materials and Devices and is the direct responsibility of Subcommittee contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
F04.22 on Arthroplasty. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Aug. 15, 2010. Published October 2010. Originally the ASTM website.
approved in 2004. Last previous edition approved in 2004 as F2385 – 04. DOI: The boldface numbers in parentheses refer to the list of references at the end of
10.1520/F2385-04R10. this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2385 − 04 (2010)
3.2.2 markers—tantalum beads 1.0 mm, 0.8 mm, or 0.5 mm 3.3.4 CMS-RSA—an RSA software program developed at
in diameter. the University of Leiden, Sweden. It utilizes sequential radio
pairs in order to measure relative displacements between two
3.2.2.1 implant markers—in vivo markers placed on the
segments (5).
implant in order to define the implant as a rigid body.
3.2.2.2 cage markers—tantalum beads held in an external
4. Significance and Use
reference frame used to create a three dimensional coordinate
4.1 This test method uses clinical radiographs of the hip
system for measuring relative displacements.
joint of a patient that has received a total hip replacement to
3.2.2.3 segment—a three dimensional rigid body defined by
measurethecombinedeffectofplasticdeformationandwearat
a minimum of three markers.
the articular interface which results in three dimensional
3.2.3 edge detection—method of image analysis used to
displacements of the femoral head into the acetabular compo-
determine the two dimensional or three dimensional center
nent.
point of a curved surface. Many computational methods of
4.2 This test method addresses the validation of the various
edge detection exist.
computational methods available for measuring the magnitude
3.2.4 coordinate system/axes—three orthogonal axes are
of creep/wear accruing at the articular surface of THRs.
defined as follows:
4.3 This test method addresses the type of radiographic
3.2.4.1 origin—the center of the coordinate system is lo-
projections needed for an analysis as well as general radio-
cated at either the geometric center of the acetabular compo-
graphic parameters needed for obtaining high quality films.
nent segment or the center of a circle defined using the edge of
4.4 This test method addresses the criterion for evaluating
the acetabular component.
clinical radiographs for inclusion in a study.
3.2.4.2 X-axis—the positive X-axis is to be directed in the
4.5 This test method addresses the conversion of radio-
medial direction independent of which hip is to be studied.
Some software programs correct the sign of this value but the graphic images to the appropriate digital format needed for the
various computer assisted computational methods.
user must insure that the protocol maintains the convention,
(that is, which way is the patient facing).
5. Validation
3.2.4.3 Y-axis—the positive Y-axis is to be fixed in the
superior direction.
5.1 Aphysical phantom model which is capable of replicat-
ing the three dimensional displacement of the femoral head at
3.2.4.4 Z-axis—the positive Z-axis is to be fixed in the
magnitudes of displacements that are expected to occur clini-
posterior direction.
cally should be used to validate new software programs,
3.2.5 radio pair—one set of RSA radiographs which were
modifications to existing programs, and variations to the
taken simultaneously.
experimental protocol which may effect the results of the
3.3 There are a number of computational methods that can
measurements. A recent publication describes such a phantom
beusedtomeasurecreep/wearofapolyethylenecomponent.A and its use (6). Figs. 1 and 2 show an example of a model
description of a few of the commonly used current methods is
which can be used for this purpose. For comparative purposes,
given. This is not meant to be at the exclusion of other the method described by Bragdon et al (6) for calculating
methods.
accuracy and precision can be used. Illustrative values for the
accuracyandprecisionasmeasuredbythismethodarelistedin
3.3.1 Martell method—as this software is informally re-
ferred to in reference to its developer Dr. John Martell of the appendix.
Chicago University, is a semi-automated computer technique
5.2 To generate data for a precision and bias statement, the
using edge detection and the Hough transformation for the
Practice E177 should be followed.
determination of polyethylene wear. This technique uses se-
quential A/P films for two dimensional analysis and A/P and
6. Material
lateral sequential films for three dimensional analysis (2).
6.1 Non-RSA Methods of Obtaining Clinical Radiographs
3.3.2 Polywear method—a software program developed by
for Measuring Femoral Head Penetration:
Dr. Peter Devane of the Wellington School of Medicine, New
6.1.1 These methods utilize anAnterior/Posterior (A/P) and
Zealand is a semi-automated computer technique using edge
across-tablelateralprojectionofthepelvis.TheA/Pprojection
detection for the determination of polyethylene wear. This
is used for measuring two dimensional penetration vector. The
technique uses sequential A/P films for two dimensional
cross-table lateral is used to determine the magnitude and
analysis and A/P and lateral sequential films for three dimen-
direction of the three dimensional penetration vector.
sional analysis (3).
6.1.2 These radiographs are typically taken in the supine
3.3.3 UmRSA—an RSA software program developed by
position. However, the A/P projections can be obtained from
Biomedical Innovations AB in Umea Sweden. It utilizes
the standing position. The method must be consistent through-
sequential radio pairs in order to measure relative displace-
out the subsequent examinations.
ments between two segments or a point relative to a segment.
It utilizes a model based edge matching method for determin- 6.1.3 The A/P projection is to be pubic centered including
ing the center of the markers (4). both hips, typically taken using a 14 by 17 film or target size.
F2385 − 04 (2010)
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 Atypicalradiographicset-upwouldhaveasourceto
plate distance of 40 in. and an exposure setting of 85 kv 40-50
maS.
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 set-up for RSAanalysis requires two
x-ray generators which are discharged nearly
...