Structural behavior of human lumbar spinal motion segments.

نویسندگان

  • Mack G Gardner-Morse
  • Ian A F Stokes
چکیده

The objectives of this study were to obtain linearized stiffness matrices, and assess the linearity and hysteresis of the motion segments of the human lumbar spine under physiological conditions of axial preload and fluid environment. Also, the stiffness matrices were expressed in the form of an 'equivalent' structure that would give insights into the structural behavior of the spine. Mechanical properties of human cadaveric lumbar L2-3 and L4-5 spinal motion segments were measured in six degrees of freedom by recording forces when each of six principal displacements was applied. Each specimen was tested with axial compressive preloads of 0, 250 and 500 N. The displacements were four slow cycles of +/-0.5mm in anterior-posterior and lateral displacements, +/-0.35 mm axial displacement, +/-1.5 degrees lateral rotation and +/-1 degrees flexion-extension and torsional rotations. There were significant increases with magnitude of preload in the stiffness, hysteresis area (but not loss coefficient) and the linearity of the load-displacement relationship. The mean values of the diagonal and primary off-diagonal stiffness terms for intact motion segments increased significantly relative to values with no preload by an average factor of 1.71 and 2.11 with 250 and 500 N preload, respectively (all eight tests p<0.01). Half of the stiffness terms were greater at L4-5 than L2-3 at higher preloads. The linearized stiffness matrices at each preload magnitude were expressed as an equivalent structure consisting of a truss and a beam with a rigid posterior offset, whose geometrical properties varied with preload. These stiffness properties can be used in structural analyses of the lumbar spine.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

The feasibility of modal testing for measurement of the dynamic characteristics of goat vertebral motion segments.

Structural vibration testing might be a promising method to study the mechanical properties of spinal motion segments as an alternative to imaging and spinal manipulation techniques. Structural vibration testing is a non-destructive measurement technique that measures the response of a system to an applied vibration as a function of frequency, and allows determination of modal parameters such a...

متن کامل

Segmental instability of the lumbar spine.

The lumbar spine, although often described as a single functional unit, is composed of 5 vertebrae forming what are called "motion segments" connected in series.5 Each motion segment consists of 2 adjacent vertebral bodies and the connecting ligaments.6 Spinal motion segments represent the smallest segments of the spine exhibiting biomechanical characteristics similar to those of the entire spi...

متن کامل

Comparative histomorphometric study of the various segments of the spinal cord in the adult male and female mongoose (Herpestes edwardsii)

Background: Anatomical and histological studies of the spinal cord have always garnered anatomists’ attention because of their high importance in various fields of veterinary medicine, zoology and behavioral science. OBJECTIVES: This work was conducted to understand the detailed histomorphometric aspects of the spinal cord of Indian gray mongoose (Herpestes edwardsii). METHODS: Six adult Indian...

متن کامل

Torso flexion loads and the fatigue failure of human lumbosacral motion segments.

STUDY DESIGN Spine loads associated with lifting a 9-kg weight were estimated at three torso flexion angles (0 degrees, 22.5 degrees, and 45 degrees), and lumbosacral motion segments were cyclically loaded using these loads until failure or to a maximum of 10,020 cycles. OBJECTIVES To simulate the postures and loads experienced by the lumbar spine during repetitive lifting of moderate weights...

متن کامل

Effect of orientation on measured failure strengths of thoracic and lumbar spine segments.

Substantial research has been performed over many years to determine the compressive failure limits of spinal motion segments. However, the majority of studies have not considered the natural alignment of the spine, testing only for pure compression loads. This study tested 27 motion segments, ranging from the T6/T7 to L4/L5 levels, from 13 human cadaveric spines. The segments were oriented in ...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • Journal of biomechanics

دوره 37 2  شماره 

صفحات  -

تاریخ انتشار 2004