• The Journal of Korean Physical Therapy
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• v.2 no.1
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• pp.103-112
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• 1990

The intervertebral disc in the anterior portion of the function unit gives the spine its flexibility. The disc is attached closely to the vertebral endplates. Between these endplates and the annulus fibrosus, the nucleus pulposus of the lumbar disc is enclosed in a circle of unyielding tissues. Compressive pressure placed on the disc is dissipated circumferentially in a passive manner In response to the greater axial forced exerted on the lumbar spine in comparison to the cervical and thoracic spines, the nucleus pulposus has its greatest surface area in the lumbar spine. The intervertebral disc is not only structure that helps diss pate stresses placed on the spine. With flexion, extension, rotation, or shear stress, the load distribution on the function unit is shared by the intervertebral disc, anterior and posterior longitudinal ligaments, the facet joints and capsules, and other ligamentous structures like the ligamentum flavum, interspinous and supraspinous ligaments, which attach to the posterior elements of the functional unit.

• Journal of Korean Neurosurgical Society
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• v.30 no.3
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• pp.358-365
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• 2001

Objectives : Although posterior lumbar fusion operations had been reported to accelerate spinal degeneration, there have been only a few studies for their biomechanical effects. We have studied the change of motion range at the vertebral joint one level above the fusion(UVJ) in pedicle screw fixation group(PSF)(n=13) where facet capsule was destroyed and in posterior lumbar interbody fusion group(PLIF)(n=8) where it was spared. Patients and Methods : The patients were divided into early(3 to 6 months) and late(over 12 months) according to postoperative follow-up period. The flexion, extension and flexion-extension angles(FA, EA, FEA) were measured at the UVJ with pre-operative, early and late post-operative films. Results : Mean age and male to female ratio were $52.7{\pm}9.3$ and 1 : 3.2. Mean follow-up periods were $144.1{\pm}30.0$ and $528.8{\pm}160.3$ days in early and late groups, respectively. The FEA and FA in the late PSF($11.8{\pm}3.1$, $8.5{\pm}2.9$) were significantly greater than pre-operative angles($7.8{\pm}3.9$, $5.1{\pm}3.7$)(p<0.01, p<0.05). All angles in the PLIF showed no significant changes with time. The FEA and FA in the late PSF($11.8{\pm}3.1$, $8.5{\pm}2.9$) were significantly greater than those of the late PLIF($7.6{\pm}2.3$, $3.4{\pm}2.0$)(p<0.01, p<0.001). All angles at early follow-up period were similar between PSF and PLIF. The EA showed no significant change in relation with follow-up period or fusion method. Conclusion : As a result, the facet capsule injury in pedicle screw fixation seems to be related with increased flexion angle or degeneration of the adjacent joint above the fused vertebra in the late phase.