ISO 22622 Implants for Surgery - Wear of Total Ankle Joint Prostheses - Loading and Displacement Parameters for Wear Testing Machines with Load or Displacement Control and Corresponding Environmental Conditions for Testing

The standard "ISO 22622 Implants for surgery - Wear of total ankle joint prostheses - Loading and displacement parameters for wear testing machines with load or displacement control and corresponding environmental conditions for testing" developed by the International Organization for Standardization (ISO) describes the relative angular motion between articulating components, the pattern of applied force, test speed and duration, specimen configuration and the test environment to be used for wear testing of total ankle joint prostheses on wear testing machines with load or displacement control. This standard is based on the method described by the ISO 14243-1 and ISO 14243-3 standards and allows the use of the same test equipment as used for wear testing of total knee prostheses.

For the purposes of this standard, the following terms and definitions apply:

• Talus component refers to the component of the total ankle joint prosthesis that is attached to the talus. It is the component that articulates against the bed.
• Tibial component refers to the component of the total ankle joint prosthesis that is attached to the tibia.
• Bearing refers to a total ankle joint prosthesis component designed to articulate with both the tibial component and talus component surfaces. The upper bearing surface supports tibial internal/external rotation and the lower bearing surface supports talus plantar/dorsiflexion.
• The frontal plane is the plane of the implant that runs medially-laterally.
• The sagittal plane is the plane perpendicular to the frontal plane.

The total ankle joint prosthesis is mounted in an apparatus that applies simultaneous cyclic rotation motion (talar plantar/dorsiflexion rotation and tibial rotation torque) and contact forces (axial and anteroposterior forces) to the interface between the tibial and talus components, simulating normal human walking. Contact force motions are scaled to an assumed body weight of 720 N.

Wear testing of a total ankle joint prosthesis in a knee simulator according to ISO 14243-1 and ISO 14243-3 standards requires an inverted position in which the talus component is in the superior position of the total ankle joint prosthesis. The tibial component position given by ISO 14243-1 and ISO 14243-3 standards remains the tibial component position of the total ankle joint prosthesis, and the femoral component position given by ISO 14243-1 or ISO 14243-3 standards becomes the talus component position of the total ankle joint prosthesis.

When performing curves, the directions of movements should not be confused due to the reverse position.

For load-controlled wear testing machines, the applied contact forces and rotational actions are axial force, anteroposterior force, talus plantar/dorsiflexion rotation, and tibial component rotation torque.

For wear testing machines with displacement control, the applied contact forces and rotation actions are axial force, anteroposterior displacement, talus plantar/dorsiflexion rotation, and tibial component internal/external rotation.

The contacting surfaces of the tibial and talus components are immersed in a liquid test medium simulating human synovial fluid. If polymers are the subject of investigation, a control sample is subjected to the liquid medium and the same time-varying axial force to determine the amount of mass change resulting from creep or fluid transfer of the test sample. Testing is performed in a controlled environment simulating physiological conditions.

Among the numerous tests, measurements, analyses and evaluations that our organization has carried out for businesses in various sectors, our organization also provides testing services defined in the standard “ISO 22622 Implants for surgery - Wear of total ankle joint prostheses - Loading and displacement parameters for wear testing machines with load or displacement control and corresponding environmental conditions for testing” with its trained and expert staff and advanced technological equipment.