Biomechanical study of pediatric human cervical spine: A finite element approach

Although considerable effort has been made to understand the biomechanical behavior of the adult cervical spine, relatively little information is avai lable on the response of the pediatric cervical spine to external forces. S ince significant anatomical differences exist between the adult and pediatr ic cervical spines, distinct biomechanical responses are expected. The pres ent study quantified the biomechanical responses of human pediatric spines by incorporating their unique developmental anatomical features. One-, thre e-, and six-year-old cervical spines were simulated using the finite elemen t modeling technique, and their responses computed and compared with the ad ult spine response. The effects of pure overall structural scaling of the a dult spine, local component developmental anatomy variations that occur to the actual pediatric spines, and structural scaling combined with local com ponent anatomy variations on the responses of the pediatric spines were stu died. Age- and component-related developmental anatomical features included variations in the ossification centers, cartilages, growth plates, vertebr al centrum, facet joints, and annular fibers and nucleus pulposus of the in tervertebral discs, The flexibility responses of the models were determined under pure compression, pure flexion, purr extension, and varying degrees of combined compression-flexion and compression-extension. The pediatric sp ins responses obtained with the pure overall (only geometric) scaling of th e adult spine indicated that the flexibilities consistently increase in a u niform manner from six- to one-year-old spines under all loading cases, In contrast, incorporation of local anatomic changes specific to the pediatric spines of the three age groups (maintaining the same adult size) not only resulted in considerable increases in flexibilities, but the responses also varied as a function of the age of the pediatric spine and type of externa l loading. When the geometric scaling effects were added to these spines, t he increases in flexibilities were slightly higher; however, the pattern of the responses remained the same as found in the previous approach, These r esults indicate that inclusion of developmental anatomical changes characte ristic of the pediatric spines has more of a predominant effect on biomecha nical responses than extrapolating responses of the adult spine based on pu rr overall geometric scaling. [S0148-0731(00)00501-X].