All technical contents in this Standard are compulsory.
This Standard is drafted in accordance with the rules of GB/T 1.1-2009.
This Standard supersedes YY 0018-2008 Implants for Osteosynthesis - Metallic Bone Screws; compared with the previous edition, this Standard has the following main technical differences:
- Terminologies and Definitions (see Chapter 3) are added;
- Sample of product model (3.1 in Edition 2008) as well as type and code of each part (3.2 in Edition 2008) are deleted;
- Bone screws are classified according to international standard ISO 5835 and ISO 9268(see Chapter 4);
- Requirements on test sample quantity and re-inspection (see 5.2.1) are added to "maximum torque and breaking angle" and specific description of fracture definition(see Appendix A) is added to test method;
- Requirement of axial pullout strength is added (see 5.2.3);
- Requirements of insertion and removal torques are added (see 5.2.4);
- Requirement of self-tapping performance is added (see 5.2.5);
- Note on "for the surface roughness of the bone screws with special surface treatment (e.g. sand blasting), relevant requirements may be established by the manufacturer according to clinical demand"(see 5.4.2) is added to "surface roughness";
- Requirements of surface treatment is added, which specifies contents related to evaluation on anodic oxidation surface treatment product (see 5.4.4);
- Requirement of head diameter d2 is added to "size" (see 5.5);
- Content of "inspection rules" is deleted (Chapter 6 in Edition 2008);
- Stipulation of "manufacture" and "sterilization" are added (see Chapters 7 and 8);
- Appendixes A, C and D are added and Appendix A of Edition 2008 is adjusted to Appendix B.
This Standard revises YY 0018-2008 Implants for Osteosynthesis - Metallic Bone Screws according to the basic requirements of YY 0341-2009 General Technological Requirements for Non-active Metallic Surgical Implementations for Osteosynthesis and by reference to ASTM F382 Standard Specification and Test Method for Metallic Bone Plates. HA and HB bone screws and their dimensions in this Standard are adopted by reference ISO 5835: 1991 Implants For Surgery - Metal Bone Screws with Hexagonal Drive Connection, Spherical Under-surface of Head, Asymmetrical Thread - Dimensions; HC and HD bone screws and their dimensions are adopted by reference ISO 9268: 1988 Implants for Surgery - Metal Bone Screws with Conical Under-surface Of Head - Dimensions.
Attention is drawn to the possibility that some of the elements of this Document may be the subject of patent rights. Issue organization of this Document shall not be held responsible for identifying any or all such patent rights.
This Standard is proposed by China Food and Drug Administration.
This Standard is proposed by and is under the jurisdiction of Subcommittee on Orthopaedic Implants of the National Technical Committee on Implants for Surgery and Orthopaedic Devices of Standardization Administration of China (SAC/TC 110/SC 1).
Drafting organizations of this Standard: Tianjin Medical Device Quality Supervision and Inspection Center and Center for Medical Device Evaluation, SFDA.
Chief drafters of this Standard: Zhang Chen, Fu Ruizhi, Zhang Wenhui, Song Duo, Liu Yinghui and Dong Wenxing.
This Standard supersedes YY 0018-2008.
Previous editions of YY 0017-2008 are as follows:
- YY 0018-1990 and YY 0018-2002;
PROFESSIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA
中華人民共和國(guó)行業(yè)標(biāo)準(zhǔn)
YY 0018-2016
Supersedes YY 0018-2008
Implants for Osteosynthesis - Metallic Bone Screws
骨接合植入物 金屬接骨螺釘
1 Scope
This Standard specifies the terms and definitions, classification, requirements, test methods, manufacture, sterilization, packaging and information supplied by manufacturer of implants for osteosynthesis - metallic bone screws.
This Standard applies to metallic bone screws (hereinafter referred to as "bone screws"), which is used for internal fracture fixation in case of orthopedic surgery, excluding spine and specially designed bone screws.
2 Normative References
The following documents for the application of this Document are essential. For dated reference, only the edition cited applies. For undated reference, the latest edition of the normative document (including any amendments) applies.
GB 4234 Stainless Steel for Surgical Implants
GB/T 4340.1 Metallic Materials - Vickers Hardness - Part 1: Test Method
GB/T 10610 Geometrical Product Specifications (GPS) - Surface Texture: Profile Method - Rules and Procedures for the Assessment of Surface Texture
GB/T 13810 Wrought Titanium and Titanium Alloy for Surgical Implants
GB/T 16886.5 Biological Evaluation of Medical Devices - Part 5: Test for in Vitro Cytotoxicity
GB 23102 Implants for surgery - Metallic Materials - Wrought Titanium -6Aluminium-7Niobium Alloy
YY/T 1074 Implants for Surgery - Measuring Method for Pitting Corrosion Potential on Stainless Products
YY 0341 General Technological Requirements for Non - Active Metallic Surgical Implants for Osteosynthesis
YY/T 0343 Liquid Penetrant Inspection of Metallic Surgical Implants
YY 0605.9 Implants for Surgery - Metallic Materials - Part 9: Wrought High Nitrogen Stainless Steel
YY/T 0640 Non-active Surgical Implants - General Requirements
YY/T 0662 Implants for Surgery - Metal Bone Screws with Asymmetrical Thread and Spherical Under-surface - Mechanical Requirements and Test Methods
YY/T 1504 Implants for Surgery - Metallic Bone Screws - Axial Pull-out Force Test Methods
YY/T 1505 Implants for Surgery - Metallic Bone Screws - Self-tapping Performance Test Methods
YY/T 1506 Implants for Surgery - Metallic Bone Screws - Rotary Torque Test Methods
ISO 5835 Implants for surgery - Metal Bone Screws with Hexagonal Drive Connection, Spherical Under-Surface of Head, Asymmetrical Thread - Dimensions
ISO 9268 Implants for surgery - Metal bone Screws with Conical Under-Surface of Head - Dimensions
3 Terms and Definitions
For the purpose of this document, the following terms and definitions apply.
3.1
Screw thread
Spiral groove on the surface of cylinder or cone. Protruding screw-type ridge is referred to as thread including crest and bottom.
3.2
Buttress thread
A kind of asymmetrical thread contour characterized by pressure flank approximately perpendicular to screw axis.
3.3
Screw head
Other end opposite to screw trailing end, which is used in combination with tool inserting screws.
3.4
Screw length
Entire measuring length from screw head to end.
3.5
Pitch
Distance between crests of adjacent threads.
3.6
Core diameter
Minimum diameter measured from thread root in screw threaded portion, also known as small diameter or root diameter.
3.7
Thread diameter
Maximum diameter measured from thread crest in screw threaded portion, also known as the maximum diameter.
3.8
Thread length
The length of threaded portion in screw measured from thread runout to screw end.
3.9
Thread runout
The intersection part between threaded portion and screw or screw head in screw.
3.10
Size
Marking indicating nominal thread diameter in screw.
3.11
Pilot hole
The hole drilled in the bone where screw trailing end inserts. Generally, pilot hole is slightly larger than core diameter of screw. Part of pilot hole may be larger to perform clearance fit if screw is used for broken bone pressuring.
3.12
Solid core
Screw excluding blank pipe along y-direction.
3.13
Cancellous screw
Screw that is mainly used for implanting cancellous bone, generally, it is provided with HB thread- alternative to be full or not.
3.14
Cortical screw
Screw that is mainly used for implanting cortical screw, generally, it is provided with HA thread with full thread.
3.15
Nontapping screw
Screw without slug slot on its trailing end. Where it is used for medium hard or hard skeleton, screw tap is generally required to insert the pilot hole prior to nontapping screw insertion.
3.16
Self-tapping screw
Screw with multiple slug slots on its end, which is used for tapping screw shape during insertion.
3.17
Partially threaded screw
Screw whose part from end to head not completely covered by thread while smooth bar is existing between both.
3.18
Gage length
Distance from fixture (e.g. chuck) to bottom of screw head.
3.19
Grip length
Length of thread fastened in fixture or other equipment.
3.20
Maximum torque
Maximum torque value of screw recorded before its torsion shear breaking, in N·m.
3.21
Breaking angle
Rotary angle of screw during its torsion faults, displayed as rapid decrease of indicated torque.
3.22
Axial pullout strength
Drawing force required to pull out the bone screw from inserted material or pull it out until damage, in N.
3.23
Insertion depth
Depth of thread section inserted in the testing material.
3.24
Insertion torque
Torque required for overcoming the friction force between screw and testing material when screw is inserted in testing material.
3.25
Removal torque
Torque required for overcoming the friction force between screw and testing material when screw is removed from testing material (e.g. counter clockwise rotation is adopted for right hand thread).
3.26
Self-tapping force
The value of axial force required by self-tapping screw to perform self-tapping, in N.
3.27
Torsional yield strength
Proportional limit that the screw can reach, in N. Translation method is adopted for determination with translation amount of 2°.
4 Classification
4.1 Types of bone screws
Bone screws include many different categories with types as shown in Table 1 and specific description methods as follows:
- HA, with spherical undersurface of screw head and shallow saw-tooth asymmetrical thread;
- HB, with spherical undersurface of screw head and deep saw-tooth asymmetrical thread;
- HC, with conical undersurface of screw head and symmetrical thread;
- HD, with conical undersurface of screw head and asymmetrical thread;
Note: Special construction or specification is specified by manufacturer in accordance with clinical demand.
Table 1 Type of Bone Screws
Thread
types Bone
screws
HA HB
HC HD
Undersurface of screw head
Spherical
Conical
Drive connection
Hexagonal
Slot Cross recess Cross-recessed head
Compound drive connection
4.2 HA bone screw
HA bone screw is as shown in Figure 1 with sizes in Table 2.
Contents
Foreword I
1 Scope
2 Normative References
3 Terms and Definitions
4 Classification
5 Requirements
6 Test Method
7 Manufacture
8 Sterilization
9 Packaging
10 Information Supplied by Manufacturer
Appendix A (Informative) Significance of Each Parameter in Mechanical Property Requirements of this Standard
Appendix B (Informative) List of Approved Method Standards for Chemical Analysis
Appendix C (Informative) List of Approved Method Standards for Metallographic Inspection
Appendix D (Normative) Description for Determination Method of Maximum Torque and Breaking Angle
Bibliography
