Wrist ligament ultimate strength: single elongation versus sequential strain testing

Four clinically significant ligaments were axially loaded to failure either in a single elongation or at increasing sequential strain levels. Single elongation strains in ultimate strength were significantly lower than those of sequential strain testing. The latter test method displayed large regions of permanent deformation, subtraction of which from subsequent strain levels shifted the strain at ultimate strength to within the standard deviation of the single elongation values. Sequential testing can thus approximate single elongation data, as well as failure strain after multiple subfailure traumas, by subtracting permanent deformations above that level