Park Young-Seop, Hyun Seung-Jae, Choi Ho Yong, Kim Ki-Jeong, Jahng Tae-Ahn
Department of Neurosurgery, Gyeongsang National University Changwon Hospital, Gyeongsang National University Graduate School of Medicine, Jinju; and.
Department of Neurosurgery, Spine Center, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Gyeonggi, Korea.
J Neurosurg Spine. 2017 May;26(5):638-644. doi: 10.3171/2016.10.SPINE16535. Epub 2017 Mar 3.
OBJECTIVE The aim of this study was to investigate the risk of upper instrumented vertebra (UIV) fractures associated with UIV screw fixation (unicortical vs bicortical) and polymethylmethacrylate (PMMA) augmentation after adult spinal deformity surgery. METHODS A single-center, single-surgeon consecutive series of adult patients who underwent lumbar fusion for ≥ 4 levels (that is, the lower instrumented vertebra at the sacrum or pelvis and the UIV of the thoracolumbar spine [T9-L2]) were retrospectively reviewed. Age, sex, follow-up duration, sagittal UIV angle immediately postoperatively including several balance-related parameters (lumbar lordosis [LL], pelvic incidence, and sagittal vertical axis), bone mineral density, UIV screw fixation type, UIV PMMA augmentation, and UIV fracture were evaluated. Patients were divided into 3 groups: Group U, 15 patients with unicortical screw fixation at the UIV; Group P, 16 with bicortical screw fixation and PMMA augmentation at the UIV; and Group B, 21 with bicortical screw fixation without PMMA augmentation at the UIV. RESULTS The mean number of levels fused was 6.5 ± 2.5, 7.5 ± 2.5, and 6.5 ± 2.5; the median age was 50 ± 29, 72 ± 6, and 59 ± 24 years; and the mean follow-up was 31.5 ± 23.5, 13 ± 6, and 24 ± 17.5 months in Groups U, P, and B, respectively (p > 0.05). There were no significant differences in balance-related parameters (LL, sagittal vertical axis, pelvic incidence-LL, and so on) among the groups. UIV fracture rates in Groups U (0%), P (31.3%), and B (42.9%) increased in sequence by group (p = 0.006). UIV bicortical screw fixation increased the risk for UIV fracture (OR 5.39; p = 0.02). CONCLUSIONS Bicortical screw fixation at the UIV is a major risk factor for early UIV compression fracture, regardless of whether a thoracolumbosacral orthosis is used. To reduce the proximal junctional failure, unicortical screw fixation at the UIV is essential in adult spinal deformity correction surgery.
目的 本研究旨在调查成人脊柱畸形手术后，上固定椎（UIV）螺钉固定（单侧皮质与双侧皮质）及聚甲基丙烯酸甲酯（PMMA）强化与UIV骨折风险之间的关系。方法 回顾性分析单中心、单术者连续收治的成年患者，这些患者均接受了≥4节段的腰椎融合手术（即骶骨或骨盆处的下固定椎以及胸腰椎脊柱的UIV [T9-L2]）。评估患者的年龄、性别、随访时长、术后即刻的矢状面UIV角度，包括几个与平衡相关的参数（腰椎前凸[LL]、骨盆入射角和矢状垂直轴）、骨密度、UIV螺钉固定类型、UIV的PMMA强化情况以及UIV骨折情况。患者分为3组：U组，15例患者UIV采用单侧皮质螺钉固定；P组，16例患者UIV采用双侧皮质螺钉固定并进行PMMA强化；B组，21例患者UIV采用双侧皮质螺钉固定但未进行PMMA强化。结果 融合节段的平均数量分别为6.5±2.5、7.5±2.5和6.5±2.5；中位年龄分别为50±29、72±6和59±24岁；U组、P组和B组的平均随访时间分别为31.5±23.5、13±6和24±17.5个月（p>0.05）。各组之间与平衡相关的参数（LL、矢状垂直轴、骨盆入射角-LL等）无显著差异。U组（0%）、P组（31.3%）和B组（42.9%）的UIV骨折率按组依次增加（p = 0.006）。UIV双侧皮质螺钉固定增加了UIV骨折的风险（比值比5.39；p = 0.02）。结论 无论是否使用胸腰骶矫形器，UIV双侧皮质螺钉固定都是早期UIV压缩骨折的主要危险因素。为减少近端交界性失败，在成人脊柱畸形矫正手术中，UIV采用单侧皮质螺钉固定至关重要。
