Total intervertebral spine disc prostheses (artificial discs) are used as motion preserving replacements for patients with damaged or degenerated discs in the spine. The development of artificial discs comes with a number of challenges that must be accounted for. Not only do prosthetic discs need to allow for movement and provide stability, but they must also keep up with everyday life (activities of daily living or ADL). Motion preserving implants also must meet a higher bar of safety and efficacy than fusion systems since they are required to preserve the anatomical motion for as long as possible. This more rigorous testing regime requires a team that understands the design challenges, regulatory environment, and the required rigor in tackling a problem such as this.
The prosthetic’s long-term ability to function in the body and perform daily activities is the impetus of its clinical use, testing of artificial discs helps establish whether or not it will do so in a clinical environment. Before submitting a new device to the FDA for approval, establishing that it is capable of long-term use is essential. This pre-clinical process predicts mid- to long-term wear characteristics of these novel devices.
The International Organization for Standardization (ISO) is a global national standard coalition that issued Standard 18192-1, the spinal disc wear test, in 2008. With the application of ISO Standard 18192-1, the mid-range wear behavior of an artificial disc is evaluated. This critical pre-clinical process, along with characterization testing (F2346 (link)) is a critical part of a successful submission.
This test assesses lumbar and cervical prostheses, but it does not apply to partial disc replacements (e.g. facet joint replacements, nucleus replacements, annuls replacements and active ISS systems. ISO 18192 specifies the range of motion, loading criteria and phasing of the axes, lateral bend, flexion extension, rotation, and compression, that the artificial disc will be subjected to. This is a coupled motion test that using axis phasing to generate an ADL (Activities of Daily Living) approximation for the device. This test is also performed in Bovine Serum to better mimic the body’s physiological condition.
