Standard Guide for Mechanical and Functional Characterization of Nucleus Devices

Importancia y uso:

5.1 Nucleus devices are generally designed to augment the mechanical function of native degenerated nucleus material or to replace tissue that has been removed during a surgical procedure. This guide outlines methods for evaluating many different types of devices. Comparisons between devices must be made cautiously and with careful analysis, taking into account the effects that design and functional differences can have on the testing configurations and overall performance, and the possibility that mechanical failure may not be related to clinical failure and inversely, that mechanical success may not be related to clinical success.

5.2 These tests are conducted in vitro to allow for analysis of the mechanical performance of the nucleus device under specific testing modalities. The loads applied may differ from the complex loading seen in vivo, and therefore the results from these tests may not directly predict in vivo performance.

5.3 These tests are used to quantify the static and dynamic properties and performance of different implant designs. The mechanical tests are conducted in vitro using simplified loads and moments. Fatigue testing in a simulated body fluid or saline may have fretting, aging, corroding, or lubricating effects on the device and thereby affect the relative performance of tested devices. Hence, the test environment and the effect of that environment, whether a simulated body fluid, normal saline bath (9 g NaCl per 1000 mL H₂O), or dry, is an important characteristic of the test and must be reported accurately.

5.4 Dynamic testing methods should be designed to answer the following questions, including but not limited to: Does the device still function as intended after cycling? Does it retain adequate performance characteristics (for example, mechanical and kinematic properties such as ROM)? Did the device wear or degrade? If there is evidence of wear or degradation of the device, it should be identified and quantified with reasonable methods generally available. The user shall distinguish between particulates generated by the device and particulates generated by the test model and fixtures if technically feasible.

Subcomité:

F04.25

Referida por:

F3292-25

Volúmen:

13.02

Número ICS:

11.040.40 (Implants for surgery, prothetics and orthotics)

Palabras clave:

dynamic tests; nucleus device; spinal implants; static tests;