Mathematical Modeling of Normal, Degenerated, and Fused Cervical Spines Using IAR’S Concept

2001 ◽  
Author(s):  
Ali Meghdari ◽  
Amir H. Bahrami
Keyword(s):  
Mathematical Modeling ◽  
Cervical Spine ◽  
Time Lag ◽  
Biomechanical Model ◽  
Specific Time ◽  
Instantaneous Axis Of Rotation ◽  
Axis Of Rotation ◽  
Flexion Extension ◽  
Head Neck ◽  
Instantaneous Axis

Abstract During flexion/extension, of the head-neck system, cervical spine undergoes a stepwise motion from the upper to lower regions with a specific time lag. Motion of each vertebrae is composed of a translation and a rotation with respect to lower vertebrae, which may be considered as an absolute rotation about an axis called Instantaneous Axis of Rotation (IAR). Location of this axis is different between normal, and degenerated spines. In this research intersegmental force-moments are evaluated and compared in normal, degenerated, and fused subjects employing a biomechanical model of head-neck system based on IAR’s concept and the results are presented.

Cervical Plate Stiffness Affects the Distribution of Loads and the Location of the Instantaneous Axis of Rotation of the Spine In Vitro

2016 ◽  
Vol 16 (10) ◽  
pp. S260-S261 ◽  
Author(s):  
Josh Peterson ◽  
Carolyn Chlebek ◽  
Ashley Clough ◽  
Alexandra Wells ◽  
Eric H. Ledet
Keyword(s):  
Instantaneous Axis Of Rotation ◽  
Axis Of Rotation ◽  
Cervical Plate ◽  
Instantaneous Axis

Kinematics of the trunk in sitting posture: An analysis based on the instantaneous axis of rotation

Ergonomics ◽  
2009 ◽  
Vol 52 (6) ◽  
pp. 695-706 ◽  
Author(s):  
Álvaro Page ◽  
Helios de Rosario ◽  
Vicente Mata ◽  
Rosa Porcar ◽  
José Solaz ◽  
...  
Keyword(s):  
Sitting Posture ◽  
Instantaneous Axis Of Rotation ◽  
Axis Of Rotation ◽  
Instantaneous Axis

Clinical and Experimental Models of the Midtarsal Joint

2006 ◽  
Vol 96 (1) ◽  
pp. 24-31 ◽  
Author(s):  
Christopher J. Nester ◽  
Andrew H. Findlow
Keyword(s):  
Lower Limb ◽  
Biomechanical Model ◽  
Experimental Models ◽  
Joint Kinetics ◽  
Instantaneous Axis Of Rotation ◽  
Axis Of Rotation ◽  
Local Reference System ◽  
Local Reference ◽  
Recent Debate ◽  
Midtarsal Joint

Recent debate and literature have provided impetus to the growing body of thought that we should not model the midtarsal joint as having two simultaneous axes of rotation but as having a single instantaneous axis of rotation. Building on this concept, we present new reference terminology and propose that descriptions of midtarsal joint kinetics and kinematics relate to moments and motion in the cardinal body planes as defined by the x-, y-, and z-axes of the local reference system of the calcaneus. This replaces the existing terminology that describes the oblique and longitudinal axes for the midtarsal joint. The purpose of the new terms of reference and terminology is to aid in the communication of ideas and concepts regarding the biomechanics of the midtarsal joint among clinicians and between researchers and clinicians. It will also allow integration of the midtarsal joint into the emerging biomechanical model of the lower limb, promote consistency in discussions of the joint, and ease understanding of the interrelationships between the kinetics and the kinematics of the articulations in the foot and lower limb and their relationship to pathology and clinical practice. (J Am Podiatr Med Assoc 96(1): 24–31, 2006)

Kinematics of the Cervical Spine: Path of the Instant Axis of Rotation in Flexion and Extension

2000 ◽  
Author(s):  
Denis J. DiAngelo ◽  
Keith Vossel ◽  
Kevin T. Foley
Keyword(s):  
Cervical Spine ◽  
Vertebral Body ◽  
Measurement System ◽  
Axis Of Rotation ◽  
Rotational Components ◽  
Flexion Extension ◽  
Vertebral Kinematics ◽  
Set Up ◽  
Flexion And Extension

Abstract Previous Biomechanical Measures of Vertebral Kinematics. White and Panjabi (1990) have suggested that the Instant Axis of Rotation (IAR) be used to describe the 2-D motion of a vertebral body. However, the location of the IAR for the cervical spine varies amongst spine researchers. White and Panjabi (1990) have suggested the IAR of each vertebra is located in the anterior region of the subjacent vertebra; Porterfield and Derosa (1995) suggest it is located in the mid-region of the subjacent vertebra; and Mameren et al. (1992) found it to lay in the central region of the vertebral body being tracked. Goel and Winterbottom (1991) stated that during flexion and extension, the axis of rotation is located somewhere within the vertebral body itself. Unfortunately, no accurate calculations of the IAR paths of the cervical spine exist; typical vertebral measurements only include the rotational components. Estimation of the vertebrae’s IAR location in vitro depends on the experimental set-up (motion and loading mechanics), anatomical structure, mathematical reduction technique, and accuracy of the measurement equipment. Crisco et al. (1994) determined the theoretical error in calculating the location of the IAR as a function of the measurement system specifications and the placement of the markers on the spinal body. Conventional tracking systems having translational resolutions of 0.1mm to 0.05mm were found to calculate the location of the IAR to within 7mm to 10mm, respectively. This error became significantly larger as the resolution of the measurement system dropped off. Most investigators only calculate the rotational components of a body’s motion and seldom calculate the error involved in their mathematical analysis. Furthermore, overall head movement is often reported (i.e., C0 to T1), but smaller flexion-extension movements of individual spinal bodies are either void in the literature or suspect to large theoretical errors. The objective of the study was to determine the IAR of the sub-axial cervical vertebral bodies under physiological flexion and extension conditions in vitro.

Sign in / Sign up

Export Citation Format

Share Document