Kurzfassung

The aim of the present study is the evaluation of the biomechanical effects on the range of motion (ROM) of adjacent lumbar segments after instrumentation with an interspinous device compared to a rigid posterior stabilization device. Interspinous devices are supposed to limit extension and expand the spinal canal at the symptomatic level, but with reduced effect on the range of motion of the adjacent segments. Eight fresh frozen human cadaver lumbar spines (L2-L5) were tested in a spinal...The aim of the present study is the evaluation of the biomechanical effects on the range of motion (ROM) of adjacent lumbar segments after instrumentation with an interspinous device compared to a rigid posterior stabilization device. Interspinous devices are supposed to limit extension and expand the spinal canal at the symptomatic level, but with reduced effect on the range of motion of the adjacent segments. Eight fresh frozen human cadaver lumbar spines (L2-L5) were tested in a spinal testing device with a moment of 7.5 Nm in flexion/extension, lateral bending and rotation with and without a preload (follower load of 400N). The ROM of the adjacent segments L2/L3 and L4/L5 was measured after implantation of Coflex® (Paradigm Spine, Wurmlingen) and Click´X (Synthes, Umkirch) into the segment L3/L4.
The Coflex device and the Click´X device caused a significant increase of ROM at both adjacent segments during all directions of motion, especially under preload, without significant difference between these devices. The ROM of the cranial adjacent segment L2/L3 tends to increase more than the ROM of the caudal adjacent segment L4/L5 after instrumentation of L3/L4.
The “dynamic” Coflex device caused a significant increase of ROM at both adjacent lumbar segments comparable to the increase of ROM after instrumentation with the rigid Click´X device.

Biomechanical effect of different interspinous devices on lumbar spinal range of motion under preload conditions
Interspinous devices are used as an alternative to the current gold standard treatment, decompressive surgery with or without fusion, for lumbar spinal stenosis. They are supposed to limit extension and expand the spinal canal and foramen at the symptomatic level, but still allow lateral bending and axial rotation in the motion segment. The aim of the present study is the biomechanical evaluation of the change of the range of motion of the affected and adjacent segments after implantation of different interspinous devices under load in all directions of motion. Eight fresh frozen human cadaver lumbar spines (L2-L5) were tested in a spinal testing device with a moment of 7.5 Nm in flexion/extension, lateral bending and rotation with and without a preload (follower load of 400N). The ROM was measured after implantation of Aperius® (Kyphon, Mannheim), In-Space® (Synthes, Umkirch), X-Stop® (Tikom, Fürth) and Coflex® (Paradigm Spine, Wurmlingen) into the segment L3/L4. All interspinous devices caused a significant reduction of extension of the instrumented segment without significantly affecting the other directions of motion. The flexion was reduced by all implants only when the follower load was applied. All devices caused a higher ROM of the whole spine during lateral bending and rotation. The actual evaluated interspinous devices led to a significant reduction of ROM during flexion-extension, but to a significant increase of ROM for the whole specimen (L2-L5) during lateral bending and rotation, which could increase the risk of adjacent segment degeneration.» weiterlesen» einklappen