The cause of axial rotation of the scoliotic spine.
To explain the cause of axial rotation in a scoliotic vertebral column, the influence of the gravitation force on a spine with a C-scoliosis has been investigated by means of a mechanical model. In this model the gravitation force takes hold of the three-dimensionally curved vertebral column eccentrically. From these reflections it appears that the axial rotation in the scoliotic spine can be explained by the moment distribution caused by this eccentrical gravitation force. The moment distribution, necessary for correction of the spine, is supposed to be opposite to the moments caused by the gravitation force. The moment distribution caused by the Harrington and the Luque spinal correction systems are compared to the calculated optimum correction moments. It appears that the moment distribution for the Harrington and Luque methods, necessary for the correction of the lateral deviation, are almost the same as the calculated correction moments. But the axial rotation appears to be increasing instead of decreasing in both correction systems.
A Self-Contained 3D Biomechanical Analysis Lab for Complete Automatic Spine and Full Skeleton Assessment of Posture, Gait and Run
Quantitative functional assessment of Posture and Motion Analysis of the entire skeleton and spine is highly desirable. Nonetheless, in most studies focused on posture and movement biomechanics, the spine is only grossly depicted because of its required level of complexity. Approaches integrating pressure measurement devices with stereophotogrammetric systems have been presented in the literature, but spine biomechanics studies have rarely been linked to baropodometry. A new multi-sensor system called GOALS-E.G.G. (Global Opto-electronic Approach for Locomotion and Spine-Expert Gait Guru), integrating a fully genlock-synched baropodometric treadmill with a stereophotogrammetric device, is introduced to overcome the above-described limitations. The GOALS-EGG extends the features of a complete 3D parametric biomechanical skeleton model, developed in an original way for static 3D posture analysis, to kinematic and kinetic analysis of movement, gait and run. By integrating baropodometric data, the model allows the estimation of lower limb net-joint forces, torques and muscle power. Net forces and torques are also assessed at intervertebral levels. All the elaborations are completely automatised up to the mean behaviour extraction for both posture and cyclic-repetitive tasks, allowing the clinician/researcher to perform, per each patient, multiple postural/movement tests and compare them in a unified statistically reliable framework.
An in vivo study of the axial rotation of the human thoracolumbar spine.
Measurements of axial rotation of the thoracolumbar spine during conditions of standing, sitting, lateral bending, and level walking were made in living subjects; Steinmann pins were inserted in various thoracolumbar spinous processes of seven male subjects, between twenty and twenty-six years old, and direct measurements were made of the angular displacement of the pins during rotation.

The subjects (standing erect, then sitting, with rotation measured relative to the fixed pelvis) turned from side to side as far as possible. In one subject, 9 degrees of rotation occurred between the first and the fifth lumbar vertebrae during standing and 8 degrees during sitting; additional rotation of approximately 10 degrees was observed at the thoracolumbar joint. An average of approximately 6 degrees was measured at each of the remaining thoracic levels. Some individual variation in the amount of axial rotation was observed in the subjects tested.

In one half of a walking cycle during normal level walking on a treadmill, 5 degrees of rotation occurred at the first thoracic vertebra and, in the opposite direction, 6 degrees at the fifth lumbar vertebra. There appeared to be a transition point (displacement node) in the sixth to eighth thoracic vertebral region above which rotation was in the direction opposite to that below.

In an additional study, axial rotation was found to occur with motion of the spine in the coronal plane, an observation that supports the concept that axial rotation is an integral motion of the thoracolumbar spine during lateral bending.