ISO 18192-3:2025

Overview

ISO 18192-3:2025 - Implants for surgery - Wear of total intervertebral spinal disc prostheses - Part 3 describes a standardized impingement-wear testing procedure and corresponding environmental conditions for evaluating wear of lumbar and cervical spinal disc prostheses under adverse impingement scenarios. The second edition extends the scope to cervical prostheses and integrates cervical testing parameters alongside lumbar guidance. The document defines test principles, required materials, apparatus, test methods and reporting requirements to simulate clinically relevant impingement and assess prosthesis performance.

Key Topics

• Scope and purpose: Simulate and evaluate wear caused by impingement (contact/restriction) during flexion, extension, lateral bending and combined motions (including axial rotation when clinically relevant).
• Test medium: Calf serum diluted with de-ionized water to 20 g ± 2 g protein per litre, prepared in accordance with ISO 18192-1 to replicate physiological lubrication.
• Specimens: Recommended minimum of six specimens (fewer allowed with justification). For polymers, include a load-soak control to measure creep and fluid uptake.
• Apparatus and control: Test machines compliant with ISO 7500-1, ISO 23788 and ISO 18192-1. Motion control accuracy of ±1° at maxima/minima and phasing tolerance of ±5%; force control phasing and magnitude tolerances of ±5%.
• Kinematics and coordinate system: Defined origin at the intersection of flexion/extension, lateral bending and axial rotation axes; axial load vector aligned with the rotation axis. Range of motion shall exceed impingement by at least 2° in the impingement direction and the impingement region must be offloaded each cycle.
• Test development: Identification of nominal centre of rotation, points of impingement (DCI), and development of time-varying load/displacement profiles prior to testing. Gravimetric measurement and method justification are provided in annexes.

Applications

• Who uses it: Spinal implant manufacturers, biomechanical test laboratories, regulatory reviewers, design engineers and R&D teams performing preclinical wear evaluation and risk assessments.
• Practical uses:
  • Pre-market verification of disc prosthesis durability under worst-case impingement.
  • Comparative testing of designs and materials (e.g., polymer vs. metal articulations).
  • Support for regulatory submissions, design iterations, and failure-mode analysis.
  • Establishing test setups and machine validation for repeatable impingement-wear results.

Related Standards

• ISO 18192-1 - Loading and displacement parameters and environmental conditions for wear testing.
• ISO 7500-1 - Calibration and verification of force-measuring systems for testing machines.
• ISO 23788 - Verification of alignment of fatigue testing machines.

For authoritative test protocols, machine setup details, and annex methods (gravimetric measurement, method justification), obtain the full ISO 18192-3:2025 standard from ISO.