Significance and Use
This test method is designed to quantify the static, dynamic, and wear characteristics of different designs of extra-discal motion preserving implants using testing medium (see 6.1) for simulating the physiologic environment at 37°C. Wear is assessed using a weight loss method in addition to dimensional analyses. Weight loss is determined after subjecting the implants to dynamic profiles specified in this test method. This information will allow the manufacturer or end user of the product to understand how the specific device in question performs under the test conditions prescribed in this test method.
This test method is intended to be applicable for extra-discal motion preserving implants. These implants augment the motion/load bearing characteristics between adjacent vertebral bodies, and thereby fully or partially support and transmit motion by means of an articulating joint or by use of compliant materials. Ceramics, metals, or polymers, or combinations thereof are used in implant design, and it is the goal of this test method to enable a comparison of the static, dynamic, and wear properties generated by these devices, regardless of material and type of device.
Abstract
This test method deals with static, dynamic, and wear testing of extra-discal motion preserving implants. These implants are intended to augment spinal stability without significant tissue removal while allowing motion of the functional spinal unit(s). Wear is assessed using a weight loss method and a dimensional analysis for determining wear of components used in extra-discal spinal motion preserving procedures, using testing medium as defined in this test method. This test method is not intended to address facet arthroplasty devices and any potential failure mode as it relates to the fixation of the device to its bony interfaces; and does not prescribe methods for assessing the mechanical characteristics of the device in translation. The static test includes the static flexion test, static extension test, static torsion test, static lateral bending test, and fatigue tests. Wear test includes flexion/extension wear assessment, rotational wear assessment, and bending wear assessment. The apparatus which shall be used includes implant components and spinal testing apparatus. The calculation and interpretation of wear results are also elaborated.
Scope
1.1 This test method is intended to provide test methods for the static, dynamic, and wear testing of extra-discal motion preserving implants. These implants are intended to augment spinal stability without significant tissue removal while allowing motion of the functional spinal unit(s).
1.2 Wear is assessed using a weight loss method and a dimensional analysis for determining wear of components used in extra-discal spinal motion preserving procedures, using testing medium as defined in this test method (6.1).
1.3 This test method is not intended to address any potential failure mode as it relates to the fixation of the device to its bony interfaces.
1.4 It is the intent of this test method to enable comparison of motion preserving, extra-discal implants with regard to kinematic, functional, and wear characteristics when tested under the specified conditions. It must be recognized, however, that there are many possible variations in the in vivo conditions. A single laboratory simulation with a fixed set of parameters may not be universally representative.
1.5 This test method is not intended to address facet arthroplasty devices.
1.6 This test method prescribes the use of pure angular rotations for assessing the mechanical characteristics of extra-discal motion preserving implants. This test method does not, however, prescribe methods for assessing the mechanical characteristics of the device in translation (for example, anterior/posterior translation), though this type of linear motion may be clinically relevant.
1.7 In order that the data be reproducible and comparable within and between laboratories, it is essential that uniform procedures are established. This test method is intended to facilitate uniform testing methods and data reporting for extra-discal motion preserving implants.
1.8 Without a substantial clinical retrieval history of spinal, motion preserving extra-discal implants, actual loading profiles and patterns cannot be delineated at the time of the writing of this test method. It therefore follows that the motion profiles specified by this test method do not necessarily accurately reproduce those occurring in vivo. Rather this method provides useful boundary/endpoint conditions for evaluating implant designs in a functional manner.
1.9 This test method is not intended to be a performance standard. It is the responsibility of the user of this test method to characterize the safety and effectiveness of the device under evaluation.
1.10 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.11 The values stated in SI units are to be regarded as the standard with the exception of angular measurements, which may be reported in either degrees or radians.
1.12 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
