Wiedenhöfer B, Akbar M, Fürstenberg C H, Carstens C, Hemmer S, Schilling C
Department für Orthopädie, Unfallchirurgie und Paraplegiologie, Stiftung Orthopädische Universitätsklinik Heidelberg, Schlierbacher Landstr. 200a, 69118, Heidelberg, Deutschland.
Orthopade. 2011 Feb;40(2):169-77. doi: 10.1007/s00132-010-1717-y.
Degeneration of the upper adjacent segment after operative treatment of degenerative spinal diseases of the lumbar spine (degenerative disc disease DDD) is an unsolved problem. There is also no consensus on whether a rigid or dynamic treatment of DDD should be carried out to protect the segments. This study was carried out to evaluate the effect of bisegmental rigid 360° fusion and bisegmental hybrid fusion on the treated segment as well as on the upper adjacent segment under the aspect of segment protection.
A total of six human spinal column preparations (L2-5) were tested under native conditions (NAT), with bisegmental rigid fusion (RIG 360°) and with hybrid fusion (Hybrid) in all three movement directions under physical load and with an preload. The range of motion (ROM) and neutral zone (NZ) were evaluated. The intradiscal pressure (IDP) was measured in the upper adjacent segment (OAS).
The RIG 360° led to a significant reduction in movement in all directions compared to NAT but Hybrid only in lateral bending (LB). In the OAS the NZ was showed a much greater increase than the ROM. The RIG 360° showed an increase of the NZ in flexion-extension of 86.8% and in LB of 49.6% as well as a significant increase in axial rotation of 52.5%. The increase in the Hybrid was not significant compared to NAT in all directions. Pressure measurements in OAS showed no significant differences for RIG 360° and for Hybrid compared to NAT for both load scenarios.
The range of motion of the treated segments for Hybrid were close to NAT in comparison to RIG 360° indicating a segment-protective effect. The hypothesis that rigid fusion has a significant effect on intersegmental mobility and the increase in intradiscal pressure in the upper adjacent segment could not be confirmed. The data indicate that the primary effect of fusion on the adjacent segment is very low but the fusion-linked increased frequency of extreme loads of the OAS falling within the significance level leads to degeneration. Even if the NZ values for Hybrid and RIG 360° do not significantly differ from NAT, the NZ alterations between the instrumentations tend to be strongly shifted in favor of Hybrid.
The data confirm that the clear and sometimes significant alterations of the NZ can be an essential factor for development of adjacent segment degeneration. A dynamic conclusion of instrumentation in the sense of a topping-off would appear to be useful if pathoanatomical indications for an intervertebral disc prosthesis are present.
腰椎退行性疾病（椎间盘退变疾病，DDD）手术治疗后上相邻节段的退变是一个尚未解决的问题。对于DDD应采用刚性还是动态治疗来保护节段也没有达成共识。本研究旨在从节段保护的角度评估双节段刚性360°融合和双节段混合融合对治疗节段以及上相邻节段的影响。
总共对六个人类脊柱标本（L2 - 5）在自然状态（NAT）下、双节段刚性融合（RIG 360°）以及混合融合（Hybrid）状态下，在物理负荷和预负荷下的三个运动方向进行测试。评估运动范围（ROM）和中性区（NZ）。测量上相邻节段（OAS）的椎间盘内压力（IDP）。
与NAT相比，RIG 360°导致所有方向的运动显著减少，而Hybrid仅在侧弯（LB）时运动减少。在OAS中，NZ的增加比ROM大得多。RIG 360°在屈伸时NZ增加86.8%，在LB时增加49.6%，并且在轴向旋转时显著增加52.5%。与NAT相比，Hybrid在所有方向上的增加均不显著。在两种负荷情况下，OAS中的压力测量显示RIG 360°和Hybrid与NAT相比均无显著差异。
与RIG 360°相比，Hybrid治疗节段的运动范围接近NAT，表明具有节段保护作用。刚性融合对节段间活动度有显著影响以及上相邻节段椎间盘内压力增加的假设未得到证实。数据表明融合对相邻节段的主要影响非常小，但与融合相关的OAS极端负荷频率增加且落在显著水平内会导致退变。即使Hybrid和RIG 360°的NZ值与NAT无显著差异，但两种器械固定之间的NZ改变倾向于强烈偏向Hybrid。
数据证实NZ的明显且有时显著的改变可能是相邻节段退变发展的一个重要因素。如果存在椎间盘假体的病理解剖学指征，从补充的意义上讲，器械固定的动态结论似乎是有用的。
