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Dynamic Mechanical Properties of Intact Human Cervical Spine Ligaments

by Ndu, Anthony

Abstract (Summary)
Most previous studies have investigated ligaments mechanical properties at slow elongation rates of less than 25 mm/s. The purpose of this study was to determine the tensile mechanical properties, at a fast elongation rate, of intact human cervical anterior and posterior longitudinal, capsular, and interspinous and supraspinous ligaments, middle-third disc, and ligamentum flavum.

A total of 97 intact bone-ligament-bone specimens (C2-C3 to C7-T1) were prepared from six cervical spines (average age: 80.6 years, range, 71 to 92 years) and were elongated to complete rupture at an average (SD) peak rate of 723 (106) mm/s using a custom-built apparatus. Non-linear force vs. elongation curves were plotted and peak force, peak elongation, peak energy, and stiffness were statistically compared (P<0.05) among ligament. A mathematical model was developed to determine the quasi-static physiological ligament elongation.

Highest average peak force, up to 244.4 and 220.0 N in the ligamentum flavum and capsular ligament, respectively, were significantly greater than in the anterior longitudinal ligament and middle-third disc. Highest peak elongation reached 5.9 mm in the intraspinous and supraspinous ligaments, significantly greater than in the middle-third disc. Highest peak energy of 0.57 J was attained in the capsular ligament, significantly greater than in the anterior longitudinal ligament and middle-third disc. Average stiffness was generally greatest in the ligamentum flavum and least in the intraspinous and supraspinous ligaments. For all ligaments, peak elongation was greater than average physiological elongation computed using the mathematical model.

Comparison of the present results with previously reported data indicated that high-speed elongation may cause cervical ligaments to fail at a higher peak force and smaller peak elongation and may be stiffer and absorb less energy, as compared to a slow elongation rate. These comparisons may be useful to clinicians for diagnosing cervical ligament injuries based upon the specific trauma.

Bibliographical Information:

Advisor:Manohar Panjabi

School:Yale University

School Location:USA - Connecticut

Source Type:Master's Thesis

Keywords:physiology cervical vertebrae longitudinal ligaments ligamentum flavum humans aged tensile strength intervertebral disk

ISBN:

Date of Publication:03/25/2008

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