ISO 6475:1989

Overview

ISO 6475:1989 specifies the mechanical requirements and test methods for metal bone screws with asymmetrical threads and spherical under-surfaces, intended for surgical implants. Developed by the International Organization for Standardization (ISO), this standard ensures uniformity and quality for bone screws used in medical device manufacturing and orthopaedic surgery. While the test results do not directly reflect clinical performance, they provide a reliable basis for product consistency and regulatory compliance. The requirements primarily apply to screws made of stainless steel, referencing ISO 5835 for dimensional compatibility and ISO 5832-1 for material properties.

Key Topics

• Mechanical Testing: ISO 6475 defines procedures for determining breaking torque and angle of rotation at failure, essential attributes ensuring that bone screws can withstand surgical stresses.
• Test Conditions: The standard outlines apparatus requirements, such as machine sensitivity, measuring range, and the method for applying torque during testing.
• Sample Selection: Only screws meeting specified dimensional standards are used for testing. Non-compliance triggers more extensive sampling and retesting procedures.
• Surface Quality: Screws must be free of defects or surface imperfections that could compromise performance or patient safety.
• Material Reference: The standard currently covers screws made of stainless steel per ISO 5832-1, and other materials may be included in future updates.
• Safety Considerations: Users are responsible for observing appropriate safety and regulatory practices, as ISO 6475 does not address all application risks.

Applications

ISO 6475 is widely used in the following areas:

• Orthopaedic Implant Manufacturing: Ensures bone screw products meet internationally recognized mechanical requirements, supporting product reliability and market acceptance.
• Quality Assurance: Provides standardized test methods for verifying the mechanical strength of surgical screws during production and quality control.
• Regulatory Compliance: Assists manufacturers in meeting medical device regulatory requirements by aligning product testing with global standards.
• Research & Development: Supports R&D teams in benchmarking new bone screw designs against standardized mechanical criteria.
• Industry Standardization: Facilitates compatibility and interoperability with related implants, instruments, and surgical tools defined in referenced ISO standards.

Manufacturers, testing laboratories, and regulatory bodies rely on ISO 6475 to confirm that bone screws deliver consistent performance under defined test conditions, thus reducing variability and potential device failure in surgical applications.

Related Standards

To ensure complete conformity and integration with surgical systems, ISO 6475:1989 should be used in conjunction with:

• ISO 5835: Specifies dimensions for metal bone screws with hexagonal drives and spherical under-surfaces, ensuring compatibility with surgical instruments.
• ISO 5832-1: Covers the properties of wrought stainless steel for implant use, establishing material requirements and traceability.
• ISO 8319-1 & ISO 8319-2: Define connection interfaces for orthopaedic instruments, covering keys and screwdrivers for various screw head designs.
• ISO 5836: Details requirements for metal bone plates with holes for compatible screws.
• ISO 9268 & ISO 9269: Address design and mechanical tests for bone plates and matching screw holes.
• ISO 9714-1: Provides specifications for drilling and tapping tools used with bone screws.

By adhering to ISO 6475 and its related standards, the medical device industry promotes safer, more effective, and globally accepted surgical implants and instruments.

Keywords: ISO 6475, surgical implants, bone screws, mechanical requirements, test methods, orthopaedic surgery, stainless steel implants, international standards, medical device testing, quality assurance, regulatory compliance.