5.1 Spinal implants are generally composed of several components that, when connected together, form a spinal implant construct. Spinal implant constructs are designed to provide some stability to the spine while arthrodesis takes place. This test method outlines standardized evaluations of different interconnection mechanisms to facilitate comparison between different designs. Comparisons must be made cautiously and with careful analysis, taking into account the effects that design differences can have on the loading configurations.

5.2 This test method is used to quantify the static and fatigue properties of different implant interconnection designs. The mechanical tests are conducted in vitro using simplified, unidirectional loads and moments. Fatigue testing in a simulated body fluid or saline may have a fretting, corrosive, or lubricating effect on the interconnection and thereby affect the relative performance of tested devices. Hence, the test environment, whether a simulated body fluid, saline (9g NaCl per 1000 mL H₂O), with a saline drip, or dry, is an important characteristic of the test and must be reported accurately.

5.3 The loading of spinal implant constructs in vivo will, in general, differ from the loading configurations used in this test method. The results obtained here cannot be used directly to predict in vivo performance. However, the results can be used to compare different component designs in terms of relative mechanical parameters.