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STUDY DESIGN Three-dimensional intervertebral motions of the subaxial cervical spine during head rotation were investigated in healthy volunteers using three-dimensional magnetic resonance imaging (MRI). OBJECTIVES To document intervertebral coupled motions of the subaxial cervical spine during rotation. SUMMARY OF BACKGROUND DATA In vivo(More)
In vivo three-dimensional (3D) kinematics of the lumbar spine has not been well evaluated by the conventional methods because of their methodological limitations, while 3D intervertebral motions have been quantitatively determined by cadaver studies. We thus developed a novel 3D analyzing system for the relative motions of individual vertebrae using 3D(More)
To justify lumbar fusion or stabilization, a quantitative assessment and definition of spinal instability are essential. To quantify spinal instability, the tensile stiffness of a motion segment (vertebra-disc-vertebra) was measured with a spinal distractor during spinal decompression surgery. Stiffness was indicated by the relationship between load and(More)
STUDY DESIGN Kinematics of the cervical spine during lateral bending were investigated using a novel system of three-dimensional motion analysis. OBJECTIVES To demonstrate in vivo intervertebral coupled motions of the cervical spine during lateral bending of the neck. SUMMARY OF BACKGROUND DATA No previous studies have successfully documented in vivo(More)
OBJECT Neurological deterioration due to spinal epidural hematoma (SEH) is a rare but significant complication of spinal surgery. The frequency of hematoma evacuation after spinal surgery is reportedly 0.1%-3%. The objective of this study was to investigate the symptomatology of SEH and the frequency of evacuation for each surgical procedure after spinal(More)
OBJECT Spinal fusion at the L4-5 disc space alters the normal biomechanics of the spine, and the loss of motion at the fused level is compensated by increased motion and load at the other unfused segments. This may lead to deterioration of the adjacent segments of the lumbar spine, called adjacent-segment disease (ASD). In this study, the authors(More)
We evaluated 30 patients with cervical myelopathy before and after decompressive surgery and compared them with 42 healthy controls. All were asked to grip and release their fingers as rapidly as possible for 15 seconds. Films recorded with a digital camera were divided into three files of five seconds each. Three doctors independently counted the number of(More)
OBJECT Although conducting cervical laminoplasty in patients with multisegmental cord compression provides good neurological results, it is not without shortcomings, including C-5 palsy, axial neck pain, and undesirable radiologically detectable changes. Postoperative kyphosis and segmental instability can cause neurological problems and are believed mainly(More)
OBJECT Double-door laminoplasty using hydroxyapatite (HA) spacers has been widely performed for compressive cervical myelopathy and has provided good neurological outcome. Although HA spacers are used for preventing reclosure of the opened laminae, they are often displaced or dislocated from their original position. The authors investigated the incidence(More)