ASTM F2694-16 (2020) pdf free.Standard Practice for Functional and Wear Evaluation of Motion-PreservingLumbar Total Facet Prostheses.
X1.1 Total facet prostheses may be manufactured in avariety of sizes，materials，and shapes with various designfeatures. The purpose of this practice is to allow for aconsistent, repeatable comparison of different total facet pros-thesis designs through a series of mechanical tests.
X1.2 The spinal implants that fall into the category of totalfacet prostheses are intended for facet replacement.All of theimplants may reside on the posterior aspect of the adjacentvertebral bodies.This practice will allow for comparison ofthese devices since the methods and loading configurationremain consistent regardless of method of application. Biologicreplacements are excluded from the scope of this practice sincebiologic structures that share the in-vivo loads vary amongdesigns，making total facet test methods inappropriate.
X1.3 Motion of the superior relative to the inferior vertebrain a “normal”in-vivo functional spinal segment is threedimensional with predominant components being: axialtranslation，flexion/extension，lateral bending, and axial rota-tion. These motions may occur independently or be coupled insome fashion. There may be predominant in-vivo coupledmotion profiles; however，if they exist,they are currentlyunknown. Ideally，the in-vivo motion profile(s) that wouldproduce the clinically relevant “worstcase” wear rate would bethe one(s) specified in this practice. It is generally accepted formany material combinations that coupled motion profiles havebeen observed to accelerate wear of some materials comparedto single-axis profiles. However，in certain materials such asmetal-on-metal or ceramic-on-ceramic，linear “simple”motions may produce the “worst-case”wear conditions. Since the“worst-case”wear rate is dependent on the material and motionprofile,and there is no known predominant coupled in-vivomotion profile(s),three different testing options are given asthe initial tests to be conducted on total facet prosthetic devices.However, no claim can be made relative to assuringthat these tests will produce the highest rate of wear. Use ofthese profiles will, however, serve as a common starting base tocompare wear rates of different total facet prosthetic devicesand their materials. As experience is gained in testing totalfacet prosthetic devices or knowledge becomes availableindicating that other profiles would produce greater wear ratesor both, the user of this practice is encourage to define, use, andreport on other potentially more detrimental motion/load profiles.ASTM F2694 pdf download.