1Department of Anatomy, Southern Medical University, Guangzhou
2Kunming General Hospital, Kunming
3Fuzhou General Hospital, Fuzhou China
Study Design: Cadaveric head-neck complexes from pediatric donors aged 2–12 years were subjected to a test battery consisting of nondestructive flexion-extension bending, nondestructive tensile step-and-hold tests, and tensile distraction loading to failure.
Objective: To characterize the biomechanical response of the pediatric cervical spine in flexion-extension bending, and the response and tolerance of the pediatric cervical spine in tensile distraction loading.
Summary of Background Data. Except for a 19th century study on stillborn infants, to our knowledge, there are no published data from human cadaveric studies on the response and tolerance of the pediatric cervical spine.
Methods: Ten unembalmed pediatric head-neck complexes with intact ligamentous cervical spines were sectioned from pediatric donors aged 2–12 years. Each specimen was potted at the level of T2 and subjected to quasi-static nondestructive flexion-extension bending by a pure moment applied to the neck. Following the flexionextension testing, each specimen was preconditioned in tension and subjected to a series of nondestructive tensile step-and-hold tests followed by tensile distraction loading to failure using a mini-Bionix MTS machine (MTS Systems Corp.).
Results: The average ± standard deviation rotational stiffness of the skull–C2, C2–T2, and skull–T2 spinal segments was 0.72 ± 0.07, 0.07 ± 0.02, and 0.04 ± 0.01 Nm/degree, respectively. Average rotational stiffness was independent of age for the range of pediatric ages tested. In the destructive tensile tests, failure occurred at an average distraction force of 726 ± 171 N and an average distraction displacement of 20 ± 3 mm. The average ultimate distraction force recorded for the 2–4-year-old specimens (595 ± 143 N) was significantly lower (P 0.05) than the corresponding average recorded for the 6–12-year-old specimens (868 ± 71 N). Average ± standard deviation linear stiffness in tensile loading was 34.7 ± 5.7 N/mm. Pediatric age did not have a statistically significant effect on the average linear stiffness.
Conclusions: The current study provides valuable new information on the response and tolerance of the pediatric cervical spine to quasi-static flexion-extension and tensile distraction loading.