Overview
ISO 22622:2019 specifies standardized procedures for wear testing of total ankle‑joint prostheses using wear‑testing machines with load control or displacement control. The standard defines the relative angular movements between articulating components, the pattern of applied forces or displacements, test speed and duration, sample configuration, and environmental (fluid) conditions to simulate physiological wear during walking. ISO 22622:2019 is based on methods from ISO 14243‑1 and ISO 14243‑3 and permits use of the same knee simulator equipment for ankle prosthesis testing.
Key topics and technical requirements
- Kinematics and sign conventions: Definitions for talar plantar/dorsiflexion rotation, tibial internal/external rotation, anterior–posterior (AP) displacement/force, axial force axis and reference position.
- Control modes: Test parameter sets for machines operating in load control (axial force, AP force, talar rotation, tibial torque) and displacement control (axial force, AP displacement, talar rotation, tibial rotation).
- Test principle: Simultaneous cyclic application of rotation and contact force actions to replicate normal gait; contact forces are scaled (note: contact forces were scaled by an assumed body weight of 720 N).
- Specimens and worst‑case selection: Test specimens include tibial and talar components plus bearing; users must justify size/design choices that represent the worst expected wear case.
- Fluid test medium: Calf serum diluted with deionized water to a protein concentration of 20 g/l ± 2 g/l, normally filtered and stored frozen; antimicrobial agents and pH monitoring are discussed.
- Use of knee simulators: Procedure for mounting ankle prostheses in an inverted position to use ISO 14243‑series knee simulators (careful attention to motion direction required).
- Controls for polymer testing: Inclusion of control specimens to measure creep and mass changes due to fluid uptake.
- Annexes: Annex A and B provide detailed load/displacement parameter tables for specified test cycles.
Applications
- Preclinical wear assessment and comparative wear studies for total ankle‑joint prostheses
- Design validation, material selection and iterative R&D for implant manufacturers
- Laboratory protocols for biomechanical testing and quality assurance
- Supporting data for regulatory submissions and safety/performance documentation
- Benchmarking and failure analysis in orthopaedic device evaluation
Who should use this standard
- Orthopaedic implant manufacturers and designers
- Biomechanical and materials testing laboratories
- Regulatory compliance teams and notified bodies
- Research groups studying joint replacement wear mechanisms
- Quality assurance and product development engineers
Related standards
Keywords: ISO 22622:2019, total ankle‑joint prostheses, wear testing, load control, displacement control, axial force, AP displacement, talar plantar/dorsiflexion, tibial rotation torque, calf serum.