This part of ISO 18192 defines a test procedure for spinal nucleus prostheses under the relative angular movement conditions specified by ISO 18192-1. This part of ISO 18192 is applicable to both lumbar and cervical prostheses. It is not applicable to total disc replacements and facet joint replacements. The method includes wear and fatigue testing. Additional mechanical tests such as creep tests can be required. Thispart of ISO 18192 does not reproduce the complex in vivo loads and motions. The wear and fatigue data obtained with this test method will enable comparison between different types of implant but can differ from the clinical wear performance. The user of this part of ISO 18192 should consider running additional tests addressing specific safety issues of the individual implant design to be tested.