ISO 22622:2019 手術用インプラント—足首関節全置換術の摩耗—荷重または変位制御を備えた摩耗試験機の荷重および変位パラメータ、および対応する試験環境条件 | ページ 5

3.1

talar component

total ankle-joint prosthesis component attached to the talus

Note 1 to entry: Component that articulates against the bearing (see Figure 1).

3.2

tibial component

total ankle-joint prosthesis component attached to the tibia

3.3

bearing

total ankle-joint prosthesis component intended for articulating with both tibial component and talar component surfaces

Note 1 to entry: The superior bearing surface supports the tibial internal/external rotation, and the inferior bearing surface supports the talar plantar/dorsiflexion (see Figure 1).

3.4

frontal plane

plane that lies in the medial-lateral direction of the implant

Note 1 to entry: See G in Figure 1.

3.5

sagittal plane

plane that lies perpendicular to the frontal plane

Note 1 to entry: See H in Figure 1.

3.6

talar plantar/dorsiflexion rotation

angular movement of the talar component of the total ankle joint-prosthesis about a medial/lateral axis

Note 1 to entry: The plantar/dorsiflexion rotation is considered to be zero when the total ankle-joint prosthesis is in the reference position (3.13) , is positive when the talar component is in dorsiflexion (+ve) and is negative when the talar component is in plantarflexion (see Figure 1).

3.7

plantar/dorsiflexion test axis

nominal axis of rotation of the talar component relative to the tibial component

Note 1 to entry: See 5 in Figure 1.

Note 2 to entry: The test axis is the line parallel to the medial/lateral axis, and intersecting with both the plantar/dorsiflexion talar design axis provided by the manufacturer and the axis of internal/external rotation of the tibial component (see Figure 2).

3.8

anterior posterior (AP) displacement

displacement of the tibial component in the sagittal plane perpendicular to the axial force axis

Note 1 to entry: AP is an abbreviation for anterior posterior.

Note 2 to entry: The displacement is considered to be zero when the total ankle-joint prosthesis is in the reference position (3.13) and is considered to be positive (+ve) when the tibial component is moved to an anterior position (see Figure 1).

3.9

anterior posterior (AP) force

force applied to the tibial component in the sagittal plane perpendicular to the axial force axis

Note 1 to entry: AP is an abbreviation for anterior posterior.

Note 2 to entry: The force is considered to be zero when the total ankle joint-prosthesis is in the reference position (3.13) and is to be considered to be positive (+ve) when it acts from posterior to an anterior direction on the tibial component (see Figure 1).

3.10

tibial internal/external rotation

rotation of the tibial component of the total ankle-joint prosthesis about the axial force axis

Note 1 to entry: The tibial rotation is considered to be zero when the total ankle-joint prosthesis is in the reference position (3.13) and is considered to be positive (+ve) when the tibial component rotates internally (see Figure 1).

3.11

axial force

normal force applied to the ankle-joint prosthesis in a direction parallel to the tibial axis

Note 1 to entry: The axial force is considered to be positive (+ve) when the tibial component is loaded towards the talar component (see Figure 1).

3.12

axial force axis

vertical line of action of the axial force taken to pass through a point on the tibial component of the total ankle-joint prosthesis which is in the centre of the medial-lateral width of the tibial component

Note 1 to entry: See 4 in Figure 1.

Note 2 to entry: The axial force axis coincides with the axis of rotation for the tibial component.

3.13

reference position

angular and linear alignment of the tibial component relative to the talar component which gives static equilibrium of the tibial component when it is loaded against the talar component by a positive axial force applied along the axial force axis, with the most proximal points on the talar bearing surface resting on the highest points on the tibial bearing surface

Note 1 to entry: The reference position is equivalent to the position of 0° talar plantar/dorsiflexion in vivo.

Note 2 to entry: For the purpose of determining the reference position, the effect of friction between the tibial and talar components is ignored.

Note 3 to entry: The reference position can be determined by geometrical calculations based on the three dimensional form of the tibial and talar surfaces. For the purpose of these calculations, the form of the tibial and talar surfaces can be taken either from design data or from co-ordinate measurements of an unworn total ankle-joint prosthesis.

Note 4 to entry: In a moderately constrained or flat design of tibial bearing component the lowest points on the tibial bearing surface can span a large (flat) range of anterior-posterior positions, such that there is no distinct lowest point. In such a situation, this definition of reference position cannot apply. In such situations, the prosthesis manufacturer should be consulted to decide what neutral position should be set and this should be noted in detail in the test report.

3.14

tibial axis

nominal longitudinal axis of the tibia, corresponding to the central axis of the medullary cavity of the proximal tibia

3.15

tibial component rotational torque

torque applied to the tibial component of the total ankle-joint prosthesis around the axial force axis

Note 1 to entry: The tibial component rotational torque is considered to be positive (+ve) when it rotates the tibial component internally (see Figure 1).

3.16

inverted position

inverted orientation of the total ankle joint-prosthesis

Note 1 to entry: To enable testing of a total ankle joint-prosthesis in a knee simulator according to ISO 14243-1 and ISO 14243-3 an inverted position of the implant is required (see Figure 3).