Overview
ISO 16402:2008 specifies a standardized laboratory procedure for flexural fatigue testing of acrylic resin cements used in orthopaedics. The standard applies to resin cements based on poly(methacrylic acid esters) and defines specimen preparation, environmental conditioning, test apparatus and the two main fatigue test methods (Wöhler S/N curve method and the low stress method). NOTE: ISO 16402:2008 does not cover clinical or user safety hazards associated with cement use.
Keywords: ISO 16402, acrylic resin cement, flexural fatigue testing, bone cement, orthopaedics, four‑point bend test, S/N curve.
Key topics and requirements
- Scope: Applies to polymerized acrylic resin cements based on poly(methacrylic acid esters).
- Specimen geometry: Rectangular bars, nominally 75 × 10 × 3.3 mm (length × width × thickness), finished with 400‑grade emery paper.
- Conditioning: Specimens stored in Ringer’s solution at 37 ± 1 °C for 4 weeks prior to testing (per ISO 16428).
- Test rig and loading:
- Four‑point bend test configuration (outer span 60 ±1 mm, inner span 20 ±1 mm) with rolling loading points.
- Bend machine capable of up to 200 N, cyclic sinusoidal loading at 5 ± 0.5 Hz, load‑controlled; minimum force 5 N.
- Quasi‑static test: increase load at 90 ± 10 N/min to fracture.
- Fatigue methods:
- S/N (Wöhler) method: typically 5 specimens per stress level, up to 5 million cycles, starting at ~80% of quasi‑static strength and stepping down.
- Low stress method: 10 specimens per level; specified stress levels 35 MPa, 25 MPa and 20 MPa; up to 5 million cycles.
- Data and reporting: Required items include cement identity (batch/lot), quasi‑static bending strength (mean ± SD), S/N diagram, fatigue strength at 5 million cycles, fatigue/quasi‑static ratio, and median lifetimes for low stress tests.
Applications and users