Patients who require total knee replacements have specific sets of needs that a prosthetic device must meet. ASTM F1223 lays out standard testing methods that provide physicians with a database of product functionality capabilities that informs their decision-making in selecting the correct prosthetic in a total knee replacement.
The constraint of a total knee replacement is an essential determinant in device selection, as some patients may have in-tact soft tissue that requires a prosthesis with lesser constraints. In contrast, other patients have destroyed ligamentous structures or suffered significant bone loss in relevant regions that warrant a total knee replacement with a higher degree of constraint. The patient’s proper matching to a functional restorative total knee replacement prosthetic requires a physician’s empirical rationale, as established through ASTM F1223 testing protocols.
Total knee replacement specimens used for testing must be “standard” or “medium” sized, as it is an egalitarian sizing that represents performance under loading regimes. Among a set of assessments is the distraction test, during which the movable component is rigidly set to move only in directions that trigger or facilitate typical distraction mechanics. The valgus-varus test is performed to test the tibial and femoral components of the total knee replacement device. This is assessed by fixing the tibial component in place, while the femoral component can freely translate mediolaterally and anterior posteriorly. Other tests that the device undergoes include an anteroposterior draw test, a mediolateral shear test, and a rotary laxity test.