Prosthetics – Testing of ankle-foot devices and foot units – Requirements and test methods (ISO 22675:2006)
Abstract
ISO 22675:2006 primarily specifies a cyclic test procedure for ankle-foot devices and foot units of external lower limb prostheses, distinguished by the potential to realistically simulate those loading conditions of the complete stance phase of walking from heel strike to toe-off that are relevant to the verification of performance requirements such as strength, durability and service life.
In addition, ISO 22675:2006 specifies a static test procedure for prosthetic ankle-foot devices and foot units, consisting of a static proof test and a static ultimate strength test, distinguished, besides other features, by the potential to generate heel and forefoot forces at lines of action conforming to those occurring at the instants of maximum heel and forefoot loading during the cyclic test.
DIN EN ISO 22675:2007-04 (E)
Prosthetics – Testing of ankle-foot devices and foot units – Requirements and test
methods (ISO 22675:2006)
Contents Page
Foreword ……………………………………………………………………………………………………………………………………….6
Introduction ……………………………………………………………………………………………………………………………………7
1 Scope ……………………………………………………………………………………………………………………………..8
2 Normative references ……………………………………………………………………………………………………..9
3 Terms and definitions ……………………………………………………………………………………………………..9
4 Designations and symbols of test forces …………………………………………………………………………9
5 Strength and related performance requirements and conditions of use ………………………….10
6 Coordinate system and test configurations ……………………………………………………………………11
6.1 General …………………………………………………………………………………………………………………………11
6.2 Origin and axes of the coordinate system ……………………………………………………………………..11
6.3 Reference points …………………………………………………………………………………………………………..12
6.4 Test force F …………………………………………………………………………………………………………………..13
6.5 Line of application of test force F …………………………………………………………………………………..13
6.6 Lines of action of resultant reference forces FR1 and FR2 ……………………………………………..13
6.7 Longitudinal axis of the foot and effective ankle joint centre ………………………………………….13
6.7.1 General …………………………………………………………………………………………………………………………13
6.7.2 Longitudinal axis of the foot ………………………………………………………………………………………….13
6.7.3 Effective ankle-joint centre, CA ……………………………………………………………………………………..14
7 Test loading conditions and test loading levels ……………………………………………………………..15
7.1 Test loading conditions …………………………………………………………………………………………………15
7.2 Test loading levels ………………………………………………………………………………………………………..15
8 Values of test forces, dimensions and cycles ………………………………………………………………..16
9 Compliance …………………………………………………………………………………………………………………..23
9.1 General …………………………………………………………………………………………………………………………23
9.2 Particular arrangements and requirements concerning the part required to connect an
ankle-foot device or foot unit to the remainder of a prosthetic structure …………………………24
9.2.1 Arrangements for testing ………………………………………………………………………………………………24
9.2.2 Requirements for claiming compliance ………………………………………………………………………….24
9.3 Number of tests and test samples required to claim compliance with this International
Standard ……………………………………………………………………………………………………………………….24
9.4 Multiple use of test samples ………………………………………………………………………………………….25
9.4.1 General …………………………………………………………………………………………………………………………25
9.4.2 Restriction …………………………………………………………………………………………………………………….25
9.5 Testing at particular test loading levels not specified in this International Standard ……….25
10 Test samples …………………………………………………………………………………………………………………26
10.1 Selection of test samples ………………………………………………………………………………………………26
10.1.1 General …………………………………………………………………………………………………………………………26
10.1.2 Selection of ankle-foot devices and foot units of appropriate size of foot ……………………….26
10.2 Types of test sample ……………………………………………………………………………………………………..27
10.2.1 Complete structure ……………………………………………………………………………………………………….27
10.2.2 Partial structure …………………………………………………………………………………………………………… 27
10.3 Preparation of test samples …………………………………………………………………………………………. 27
10.4 Identification of test samples ……………………………………………………………………………………….. 28
10.5 Alignment of test samples ……………………………………………………………………………………………. 28
10.6 Worst-case alignment position of test samples …………………………………………………………….. 28
11 Responsibility for test preparation ……………………………………………………………………………….. 30
12 Test submission document ………………………………………………………………………………………….. 31
12.1 General requirements ………………………………………………………………………………………………….. 31
12.2 Information required for test samples …………………………………………………………………………… 31
12.3 Information required for tests ………………………………………………………………………………………. 32
12.3.1 General ……………………………………………………………………………………………………………………….. 32
12.3.2 For all tests ………………………………………………………………………………………………………………….. 32
12.3.3 For the static proof test and the static ultimate strength test ………………………………………… 32
12.3.4 For the static ultimate strength test ……………………………………………………………………………… 32
12.3.5 For the cyclic test ………………………………………………………………………………………………………… 32
13 Equipment …………………………………………………………………………………………………………………… 33
13.1 General ……………………………………………………………………………………………………………………….. 33
13.2 End attachments ………………………………………………………………………………………………………….. 33
13.2.1 General ……………………………………………………………………………………………………………………….. 33
13.2.2 Proof test of end attachments ………………………………………………………………………………………. 33
13.3 Jig (optional) ……………………………………………………………………………………………………………….. 35
13.4 Test equipment ……………………………………………………………………………………………………………. 35
13.4.1 Test equipment to perform static heel and forefoot loading ………………………………………….. 35
13.4.2 Test equipment to perform cyclic loading …………………………………………………………………….. 37
14 Accuracy ……………………………………………………………………………………………………………………… 44
14.1 General ……………………………………………………………………………………………………………………….. 44
14.2 Accuracy of equipment ………………………………………………………………………………………………… 44
14.3 Accuracy of procedure ………………………………………………………………………………………………… 45
15 Test principles …………………………………………………………………………………………………………….. 45
15.1 General ……………………………………………………………………………………………………………………….. 45
15.2 Static test procedure ……………………………………………………………………………………………………. 46
15.3 Cyclic test procedure …………………………………………………………………………………………………… 46
16 Test procedures …………………………………………………………………………………………………………… 46
16.1 Test loading requirements ……………………………………………………………………………………………. 46
16.1.1 Preparation for test loading ………………………………………………………………………………………….. 46
16.1.2 Test loading conditions ……………………………………………………………………………………………….. 50
16.2 Static proof test …………………………………………………………………………………………………………… 50
16.2.1 Test method ………………………………………………………………………………………………………………… 50
16.2.2 Performance requirement …………………………………………………………………………………………….. 52
16.2.3 Compliance conditions ………………………………………………………………………………………………… 52
16.3 Static ultimate strength test …………………………………………………………………………………………. 54
16.3.1 Test method ………………………………………………………………………………………………………………… 54
16.3.2 Performance requirements …………………………………………………………………………………………… 57
16.3.3 Compliance conditions ………………………………………………………………………………………………… 57
16.4 Cyclic test ……………………………………………………………………………………………………………………. 59
16.4.1 Test method ………………………………………………………………………………………………………………… 59
16.4.2 Performance requirements …………………………………………………………………………………………… 61
16.4.3 Compliance conditions ………………………………………………………………………………………………… 62
17 Test laboratory/facility log ……………………………………………………………………………………………. 65
17.1 General requirements ………………………………………………………………………………………………….. 65
17.2 Specific requirements ………………………………………………………………………………………………….. 65
18 Test report …………………………………………………………………………………………………………………… 65
18.1 General requirements ………………………………………………………………………………………………….. 65
18.2 Specific requirements ………………………………………………………………………………………………….. 66
18.3 Options …………………………………………………………………………………………………………………………66
19 Classification and designation ………………………………………………………………………………………66
19.1 General …………………………………………………………………………………………………………………………66
19.2 Examples of classification and designation …………………………………………………………………..66
20 Labelling ……………………………………………………………………………………………………………………….67
20.1 General …………………………………………………………………………………………………………………………67
20.2 Use of mark “*)” and warning symbol …………………………………………………………………………….68
20.3 Examples of label layout ……………………………………………………………………………………………….68
20.4 Label placement ……………………………………………………………………………………………………………69
Annex A (informative) Reference data for the specification of the test loading conditions and test
loading levels of this International Standard ………………………………………………………………….70
Annex B (informative) Guidance on the application of an alternative static ultimate strength test …..78
Annex C (informative) Guidance on the application of an additional test loading level P6 ………………79
Annex D (informative) Summary of the records to be entered in the test laboratory/facility log ………81
Annex E (informative) Information on Technical Report ISO/TR 22676 [1] ………………………………………87
Annex F (informative) Reference to the essential principles of safety and performance of medical
devices according to ISO/TR 16142 ……………………………………………………………………………….98
Bibliography …………………………………………………………………………………………………………………………………99
Annex ZA (informative) Clauses of this European Standard addressing essential requirements
Figure 1 — Coordinate system with reference parameters ………………………………………………12
Figure 2 — Determination of longitudinal axis of foot (see 6.7.2) and effective ankle-joint centre CA
(see 6.7.3) ……………………………………………………………………………………………………………………..14
Figure 3 — Illustration of reference points for the establishment of thresholds listed in Table 10 for
specification of the loading profile of the cyclic test ………………………………………………………21
Figure 4 — Illustration of specific set-up of left-sided test sample with top load application point PT 30
Figure 5 — Diagrammatic view of test equipment according to 13.4.1 and 13.4.2 with test sample …..42
Figure 6 — Profiles of test force Fc(t) and tilting angle (t) as synchronized functions of time,
determining the loading condition of the cyclic test of this International Standard …………43
Figure 7 — Test force Fc() of test loading level P5 as function of tilting angle (t) of foot platform …….44
Figure 8 — Preparation for test loading of static test procedure [see 16.1.1 a)] ……………………………….49
Figure 9 — Flowchart for the static proof test specified in 16.2.1 …………………………………………………….53
Figure 10 — Flowchart for the static ultimate strength test specified in 16.3.1 …………………………………58
Figure 11 — Flowchart for the cyclic test specified in 16.4.1 Continued on Figure 12 ………………………63
Figure 12 — Flowchart for the cyclic test specified in 16.4.1 Continued from Figure 11 …………………..64
Figure 13 — General concept for the label layout ……………………………………………………………………………67
Figure 14 — Models for the label layout ………………………………………………………………………………………….68
Figure A.1 — Illustration of different components of loading ………………………………………………………….76
Figure A.2 — Illustration of the dependence of the position of the top load application point PT on
the foot length L — (see A.2.2.3) ……………………………………………………………………………………. 77
Figure E.1 — Effect of f-position of tilting axis TA of foot platform on the elevation E of the foot at
the instants of heel contact and toe-off ………………………………………………………………………… 90
Figure E.2 — Effect of u-position of tilting axis TA of foot platform on the A/P displacement f of the
foot at the instant of toe-off ………………………………………………………………………………………….. 91
Figure E.3 — Illustration of the effect of A-P displacement f on the angular movement of the test
sample about the top load application point PT ……………………………………………………………. 92
Figure E.4 — Illustration of possibilities of transposing the top load application point PT for
compensation of the dependence of the position of the tilting axis TA of the foot
platform on the foot length L ………………………………………………………………………………………… 95
Figure E.5 — Illustration of the effect of a fixed compromise offset uTA, C of the tilting axis TA of
the foot platform on the A-P displacement f at the foot [see E.3.4.2 c) 2)] ………………………. 96
Table 1 — Designations and symbols of test forces ………………………………………………………………………… 9
Table 2 — Categories of strength addressed in this International Standard, together with the related
performance requirements and test methods for their verification ………………………………… 10
Table 3 — Test forces and relevant references ……………………………………………………………………………… 16
Table 4 — Values of bottom offsets fB1, L (heel) and fB2, L (forefoot) for given values of foot length
L, relevant to the design and/or adjustment of the rigid foot dummy required to simulate
or other provisions of EU Directives …………………………………………………………………………… 100
the effective lever arms of an ankle-foot device or foot unit in the proof test of end attachments
(see 13.2.2) ………………………………………………………………………………………………………………….. 17
Table 5 — Test forces of the proof test of end attachments for test loading levels P5, P4 and P3
(see 13.2.1) ………………………………………………………………………………………………………………….. 17
Table 6 — Total length of test samples and segmental lengths of end attachments ……………………….. 18
Table 7 — Coordinates of top load application point PT and tilting axis TA of foot platform based on
given values of foot length L, for all test loading levels ………………………………………………… 19
Table 8 — Angles of toe-out position of foot and specific tilting positions of foot platform, for all
test loading levels ……………………………………………………………………………………………………….. 19
Table 9 — Test forces for all tests and prescribed number of cycles for the cyclic test, for test
loading levels P5, P4 and P3 (see 16.2, 16.3 and 16.4) …………………………………………………… 20
Table 10 — Thresholds according to Figure 3 for specification of the application of the loading
profile of the cyclic test ……………………………………………………………………………………………….. 22
Table 11 — Data specifying the values of tilting angle (t) and test force Fc(t) illustrated in Figure 6
in 30 ms time increments for guidance on their application ………………………………………….. 23
Table 12 — Number of tests and test samples required to claim compliance with this International
Standard ……………………………………………………………………………………………………………………… 26
Table 13 — Option for end attachments of specific design ……………………………………………………………. 33
Table A.1 — Magnitudes of resultant reference forces FR1x and FR2x ………………………………………….. 73
Table C.1 — Test forces of the proof test of end attachments for test loading level P6 (see 13.2.2.1) 79
Table C.2 — Test forces for all tests and prescribed number of cycles for the cyclic test, for test
loading level P6 (see 16.2, 16.3 and 16.4) ……………………………………………………………………….80
Table E.1 — Contents of ISO/TR 22676 and list of corresponding clauses/subclauses of this
International Standard, in which selected items are dealt with ……………………………………….88
Table E.2 — Possibilities of transposing the top load application point PT for compensation of the
dependence of the position of the tilting axis TA of the foot platform on the foot length L 97
Table F.1 — Correspondence between this International Standard and the essential principles of
ISO/TR 16142 ………………………………………………………………………………………………………………..98