Naslov
Shifting of the Nucleus Pulposus in Lumbar Syndrome

Autori
Jurčević-Lulić, Tanja ; Paladino, Josip ; Papa, Juraj

Vrsta, podvrsta i kategorija rada
Radovi u zbornicima skupova, cjeloviti rad (in extenso), znanstveni

Izvornik
Pain Management 98 / Erasmus Forum - Rotterdam : Boston (MA) : Taipei : Erasmus Forum, 1998, 98-99

Skup
Pain Management 98 (FBSS)

Mjesto i datum
Rotterdam, Nizozemska, 09.11.1998. - 12.11.1998

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
lumbar spine kinematics; motion of the nucleus pulposus; pressure

Sažetak
Kinetic analysis of the lumbar spine and lumbosacral curvature is a very complicated because of three-dimensional motion with high number of degrees of freedom, which significantly impede a precise mechanical analysis. In the existing literature of lumbar spine kinematics there are different, and sometimes contradictory statements which incited us to the investigation of relative motions between lumbar vertebrae. During the load transfer in the lower spine and lumbosacral curvature each vertebra is complexly loaded, meaning that besides compression and tension, there are also bending and torsion loading. In this complex chain transferable system the intervertebral disk and vertebral body are dampers of axial dynamic load. The spinal bending forwards and backwards has been analysed by relative turning of the body of vertebra towards to the body of another vertebra, which remained immobile. At this rotation connective fibres lengthen in some parts of annular layers since the distances between vertebral folds increased and there were the distances decreased, the fibres got deformed. Lengthened connective fibres of the internal round layers of the fibrous ring (annulus), like the sides of the bow, try to push forward the nucleus pulposus and to move its center forwards too. If the bending of the spine is in the lateral level backwards, then the described shift will be converse, and the nucleus pulposus will be directed backwards. Since in early adolescence the gelatinous characteristics of the nucleus pulposus decreases, the mass changes into a resistance substance conditioning the occurrence of stronger links between the nucleus and the surfaces of the upper and lower vertebrae, so, by the bending of vertebral bodies the nucleus will be significantly resist to the shift dictate by the fibrous ring. Therefore, tensions of connective fibres during the bending forwards and backwards cannot push the mass of the nucleus pulposus and high contact pressure occurs between gelatinous solidified nucleus and fibrous ring. This pressure can probably cause initial ruptures of the fibrous ring fibres. The carried out analysis of the simplified model of a vertebral segment, as well as the x-ray confirmation of functional motions, undoubtly indicate that nucleus pulposus center in lumbar spine moves towards the center of the instantaneous spine curvature. By analogy the shifts of the nucleus pulposus even in the lateral bending of the body (or any other direction) occur in the same direction as the bending does. We would like to note, that prolapsed disk the gelatinous nucleus discharges regardless the direction of bending, and that it only depends on differences in pressures in intervertebral and intermedular region. The carried out analysis also points out another fact, which can somewhat serve in explanation of the intervertebral disk damage occurrence. Namely, if results in the transformation of the pulposus nucleus into degenerated nucleus, it causes the pressure increasing in the border region with the fibrous ring layers, which gathered together with various kinds of loads (especially torsion) can cause initial ruptures of the ring. These initial ruptures gradually change into macrodemage, and in the end into complete prolapse of the intervertebral disk.

Izvorni jezik
Engleski

Znanstvena područja
Strojarstvo

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