ISO 9268:1988

Overview

ISO 9268:1988 - "Implants for surgery - Metal bone screws with conical under‑surface of head - Dimensions" is an international standard that specifies the dimensions and tolerances for metal bone screws with a conical under‑surface on the head used in surgery. Published in 1988 (first edition), it consolidates and replaces earlier parts of the ISO 5835 series and defines standardized geometries that ensure compatibility with plates, instruments and driving tools.

Key topics and technical requirements

• Scope and exclusions: Defines standard forms only; bone screws for particular or special applications are not covered.
• Thread forms: Specifies two primary thread families used in the standard - symmetrical (HC) and asymmetrical (HD) - with dimensional tables and profiles for each.
• Drive connections: Details approved drive types and head designs, including single‑slot, cruciate‑slot, combined single/cruciate with cross‑recessed, and cross‑recessed drive connections. Notes on recess depth and torque integrity are included.
• Head under‑surface: Defines the conical under‑surface geometry to ensure correct seating in corresponding plate holes and mechanical interfaces.
• Dimensions and tolerances: Provides figures and tabulated dimensional limits for nominal diameters, thread profiles, head dimensions and related tolerances.
• Self‑tapping provision: Allows suitable flutes to be added to screw bodies to create self‑tapping variants, where specified.
• Marking and packaging: Requires marking, packaging and labelling to comply with ISO 6018 (orthopaedic implant general requirements).
• Informative Annex A: Illustrates the interrelationship between this standard and other International Standards covering bone screws, bone plates and relevant tools - important for system compatibility.

Practical applications

• Ensures interchangeability between screws, plates and driving tools across manufacturers.
• Guides design and production of standard orthopaedic bone screws with conical head seating.
• Supports quality control and inspection/acceptance testing by providing dimensional tolerances.
• Aids procurement and regulatory documentation by specifying standardized geometries and labelling requirements.

Who should use this standard

• Orthopaedic implant manufacturers and product designers
• Surgical instrument makers (drivers, taps, countersinks)
• Quality, compliance and regulatory teams in medical device companies
• Test laboratories and inspection units
• Hospitals and procurement specialists evaluating implant compatibility

Related standards

• ISO 6018 - Marking, packaging and labelling requirements
• ISO 9269 - Bone plates - holes/slots corresponding to conical head screws
• ISO 5835 series, ISO 8319 (drive connections), ISO 6475 (mechanical requirements/testing), ISO 9714 (drills/taps) - referenced for complementary requirements and tool compatibility.

Keywords: ISO 9268:1988, metal bone screws, conical under‑surface, bone screw dimensions, surgical implants standard, thread form HC HD, drive connections, ISO 6018.