Department of Orthopedic Surgery, Spine and Scoliosis Service, Hospital for Special Surgery/Weill Cornell Medical Center, New York, NY 10021, USA.
Spine (Phila Pa 1976). 2013 Mar 1;38(5):415-8. doi: 10.1097/BRS.0b013e31826ff084.
Retrospective case-control study.
To determine the association of Hounsfield unit (HU) measurements with adjacent segment fractures after spinal fusion.
Adjacent segment fracture is a potentially devastating complication after spinal fusion surgery in osteoporotic patient. Recently, a technique for assessing bone mineral density using HU measurements from computed tomography was described and correlated with both dual-energy x-ray absorptiometry-assessed bone mineral density and compressive strength in an osseous model.
Patients with adjacent segment fractures after spinal fusion were identified from a prospectively collected patient database and matched 1:1 with nonfracture controls on the basis of age, sex, and fusion construct. Minimum follow-up was 6 months. Patients with metabolic bone disease other than osteoporosis or those taking medications known to negatively alter bone strength were excluded. HU assessment was done according to the previously published protocol using the preoperative computed tomography.
Twenty patients had complete imaging data and could be matched to nonfracture controls. The groups were well matched with respect to age, sex, body mass index, and number of levels fused. Following the index surgical procedure, the fracture group had more positive sagittal balance than the control group (10.7 cm vs. 9.1 cm). Analysis of HU values at the fracture level showed a significantly lower value in the fracture group than in the controls (145.6 vs. 199.4, P = 0.006). Similarly, global assessment of HU across the thoracic and lumbar spines was significantly lower in the fracture group (139.9 vs. 170.1, P = 0.032).
HU was significantly lower both locally and globally in the fracture cohort. Because computed tomographic scans are frequently part of preoperative planning for spinal fusion, this information should be incorporated in preoperative planning. Studies to prospectively validate HU as a predictor of adjacent segment fracture risk and to assess the effect of increasing HU preoperatively with medications for osteoporosis are needed.
回顾性病例对照研究。
确定 Hounsfield 单位 (HU) 测量值与脊柱融合后相邻节段骨折的关系。
在骨质疏松症患者中，脊柱融合手术后发生相邻节段骨折是一种潜在的灾难性并发症。最近，一种使用 CT 中的 HU 测量值评估骨密度的技术被描述出来，并与双能 X 射线吸收法评估的骨密度和骨模型中的抗压强度相关联。
从前瞻性收集的患者数据库中确定脊柱融合后发生相邻节段骨折的患者，并根据年龄、性别和融合结构与非骨折对照组进行 1:1 匹配。最低随访时间为 6 个月。排除患有除骨质疏松症以外的代谢性骨病或服用已知会降低骨强度的药物的患者。根据先前发表的方案，使用术前 CT 进行 HU 评估。
20 例患者有完整的影像学数据，可与非骨折对照组相匹配。两组在年龄、性别、体重指数和融合节段数量方面匹配良好。在索引手术之后，骨折组的矢状面平衡比对照组更差（10.7cm 对 9.1cm）。对骨折水平的 HU 值进行分析显示，骨折组的 HU 值明显低于对照组（145.6 对 199.4，P = 0.006）。同样，在骨折组中，整个胸腰椎的 HU 总体评估也明显较低（139.9 对 170.1，P = 0.032）。
HU 在骨折组中无论是局部还是整体都明显较低。由于 CT 扫描通常是脊柱融合术前计划的一部分，因此应将此信息纳入术前计划。需要前瞻性验证 HU 作为预测相邻节段骨折风险的指标，并评估术前用骨质疏松症药物增加 HU 的效果。
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