Mende Klaus Christian, Eicker Sven Oliver, Weber Friedrich
Department of Neurosurgery, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany.
Praxis für Neurochirurgie und Wirbelsäulentherapie, Bertram Blankstr. 8b, 51427, Bergisch Gladbach, Germany.
Neurosurg Rev. 2018 Jan;41(1):267-274. doi: 10.1007/s10143-017-0850-z. Epub 2017 Apr 4.
Subsidence of interbody cages is a frequently observed and relevant complication in anterior cervical discectomy and fusion (ACDF). Only a handful of studies concentrated on the modality of subsidence and its clinical impact. We performed a retrospective analysis of ACDF patients from 2004 to 2010. Numeric analog scale (NAS) score pre-op and post-op, Oswestry Disability Index (ODI) on x-rays, endplate (EP) and cage dimensions, implant position, lordotic/kyphotic subsidence patterns (>5°), and cervical alignment were recorded. Subsidence was defined as height loss >40%. Patients were grouped into single segment (SS), double segment (DS), and plated procedures. We included 214 patients. Prevalence of subsidence was 44.9% overall, 40.9% for SS, and 54.8% for DS. Subsidence presented mostly for dorsal (40.7%) and mid-endplate position (46.3%, p < 0.01); dorsal placement resulted in kyphotic (73.7%) and central placement in balanced implant migration (53.3%, p < 0.01). Larger cages (>65% EP) showed less subsidence (64.6 vs. 35.4%, p < 0.01). There was no impact of subsidence on ODI or alignment. NAS was better for subsided implants in SS (p = 0.06). Cages should be placed at the anterior endplate rim in order to reduce the risk of subsidence. Spacers should be adequately sized for the respective segment measuring at least 65% of the segment dimensions. The cage frame should not rest on the vulnerable central endplate. For multilevel surgery, ventral plating may be beneficial regarding construct stability. The reduction of micro-instability or over-distraction may explain lower NAS for subsided implants.
椎间融合器下沉是颈椎前路椎间盘切除融合术（ACDF）中常见且相关的并发症。仅有少数研究关注下沉的方式及其临床影响。我们对2004年至2010年的ACDF患者进行了回顾性分析。记录术前和术后的数字模拟量表（NAS）评分、X线片上的奥斯维斯特里功能障碍指数（ODI）、终板（EP）和融合器尺寸、植入物位置、前凸/后凸下沉模式（>5°）以及颈椎对线情况。下沉定义为高度损失>40%。患者分为单节段（SS）、双节段（DS）和带钢板手术组。我们纳入了214例患者。总体下沉发生率为44.9%，SS组为40.9%，DS组为54.8%。下沉主要出现在背侧（40.7%）和终板中部位置（46.3%，p<0.01）；背侧放置导致后凸（73.7%），中央放置导致植入物平衡移位（53.3%，p<0.01）。较大的融合器（>65%EP）下沉较少（64.6%对35.4%，p<0.01）。下沉对ODI或对线无影响。SS组中，下沉植入物的NAS评分较好（p=0.06）。为降低下沉风险，融合器应放置在终板前缘。椎间融合器的尺寸应与相应节段相匹配，至少为节段尺寸的65%。融合器框架不应置于易受损的中央终板上。对于多节段手术，腹侧钢板固定可能有助于提高结构稳定性。微不稳定性或过度撑开的减少可能解释了下沉植入物NAS评分较低的原因。
