Biomechanische Studien der thorakalen Wirbelsäule

Zusammenfassung

Die thorakale Wirbelsäule unterscheidet sich hinsichtlich ihrer biomechanischen Eigenschaften deutlich von der zervikalen und lumbalen Wirbelsäule. Wesentliche Einflussfaktoren für das charakteristische biomechanische Verhalten stellen neben den relativ flachen Bandscheiben die thorakale Kyphose und der Brustkorb dar. Die thorakale Wirbelsäule zeigt deutliche gekoppelte Bewegungen zwischen Seitneigung und axialer Rotation, die primär durch die kyphotische Krümmung verursacht werden. Alle Brustkorbstrukturen begrenzen die Flexibilität der thorakalen Wirbelsäule, insbesondere jedoch die sternokostale Verbindung, die den oberen und mittleren Bereich stabilisiert. Der Brustkorb reduziert nicht nur den Bewegungsumfang der thorakalen Wirbelsäule, v.a. in axialer Rotation, sondern verringert auch den intradiskalen Druck, erhöht die Steifigkeit, und vergrößert den Kompressionswiderstand. Die Kinematik der thorakalen Wirbelsäule wird insbesondere durch die Bandscheibe und die Facettengelenke bestimmt und stark von Degeneration beeinflusst, v.a. in Flexion/Extension. Zudem führt Degeneration zu nicht linearen intradiskalen Druckanstiegen und sogar negativen Druckwerten. Chirurgische Eingriffe und traumatische Verletzungen, auch des Brustkorbs, führen generell zu einer Destabilisierung der thorakalen Wirbelsäule, jedoch kann der stabilisierende Einfluss eines intakten Brustkorbs bei Frakturen die Möglichkeit für eine kurze posteriore Instrumentierung bieten sowie Anschlusssegmentdegeneration verringern.

Abstract

The biomechanical properties of the thoracic spine largely differ from those of the cervical and lumbar spine. Apart from the relatively flat intervertebral discs, essential determinants for the characteristic biomechanical behavior are the thoracic kyphosis and the rib cage. The thoracic spine exhibits considerable coupled motions between lateral bending and axial rotation, which are primarily caused by the kyphotic curvature. Every rib cage structure limits the flexibility of the thoracic spine, especially the sternocostal connection, which stabilizes the upper and middle section. The rib cage not only reduces the range of motion of the thoracic spine, particularly in axial rotation, but also decreases the intradiscal pressure, enlarges the stiffness, and increases the compression resistance. Thoracic spinal kinematics is especially determined by the intervertebral disc and the facet joints and is affected by disc degeneration, specifically in flexion/extension. Moreover, disc degeneration results in non-linear intradiscal pressure increases and even negative pressure values. Surgical interventions and traumatic injuries, also of the rib cage, generally lead to destabilization of the thoracic spine. However, the stabilizing effect of an intact rib cage can provide the option of short posterior instrumentation in case of fractures and can reduce adjacent segment degeneration.

Schlüsselwörter

Thorakale Wirbelsäule - Brustkorb - Biomechanik - Bewegungsumfang - Neutrale Zone - Gekoppelte Bewegungen - Kinematik - Center of Rotation - Helikale Achsen - Intradiskaler Druck

Keywords

Thoracic spine - Rib cage - Biomechanics - Range of motion - Neutral zone - Coupled motions - Kinematics - Center of rotation - Helical axes - Intradiscal pressure

Publication History

Article published online:
02 May 2023

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