Department of Pediatric Orthopedics, Cohen Children's Medical Center, New Hyde Park, NY.
Department of Orthopedic Surgery, Nicklaus Children's Hospital, Miami, FL.
Spine (Phila Pa 1976). 2017 Nov 15;42(22):E1305-E1310. doi: 10.1097/BRS.0000000000002153.
MINI: The objective of this study was to determine the safety limits of anterior/anterolateral pedicle screw breaches. Through clinical and cadaveric study, it appears that less than 4 mm of breach has a significantly lower likelihood of impingement on vital structures (P < 0.001).
Clinical retrospective chart review and basic science study.
To determine the safety limits of an anterior/anterorolateral misplaced pedicle screw on computed tomography (CT) scan in spinal deformity.
Although the limits of medial breaches (<4 mm) are known, the safe limits for anterior/anterolateral breaches in spine deformity are not yet defined.
The present study had two parts. In part I, postoperative CT scans of 165 patients operated on for spine deformity were reviewed for screw misplacement (2800 screws). The amount of anterior/anterolateral breach was measured. Protrusions were also evaluated for proximity to vital structures. All scans were reviewed by musculoskeletal radiologist. In part II, eight cadavers were instrumented with 6 × 30 and 6 × 40 mm bilaterally from T1-S1. Screws were randomly inserted under navigation guidance either "IN" or "OUT-anterior/lateral." CT scan was performed, followed by gross dissection to determine screw position.
Part I: 116(4.2%) screws were misplaced anterior/anterolaterally. Thirty-one (26.7%) were adjacent to vital structures. Fisher exact test showed 4 mm or less breach has significantly lower likelihood of impingement (P < 0.001). Screws adjacent/impinging the aorta protruded an average 5.7 ± 0.6 mm, whereas screws not involving the aorta breached an average 3.9 ± 0.2 mm, (P < 0.001). Part II: 285 screws were inserted. On CT scan, 125 were misplaced anterior/anterolaterally. On gross dissection, 89 were visibly misplaced; 23 were covered entirely by soft tissue but were palpable; and 13 were contained in bone. All 23 screws did not endanger any structures and protruded less than 4 mm on CT scan.
Anterior/anterolateral breaches of 4 mm or less on CT poses no significant risk of impingement and therefore can be considered safe.
确定脊柱畸形患者前路/前外侧置钉螺钉偏位在 CT 扫描时的安全界限。
临床回顾性图表回顾和基础科学研究。
虽然内侧偏位（<4mm）的安全界限是已知的，但脊柱畸形前路/前外侧偏位的安全界限尚未确定。
本研究分为两部分。在第一部分中，对 165 例脊柱畸形患者的术后 CT 扫描进行了回顾性研究，共分析了 2800 枚螺钉，测量了前路/前外侧螺钉的偏位程度，并评估了突起与重要结构的接近程度。所有扫描均由肌肉骨骼放射科医生进行评估。在第二部分中，8 具尸体双侧 T1-S1 植入 6×30 和 6×40mm 器械，在导航引导下随机将螺钉插入“IN”或“OUT-前/外侧”。行 CT 扫描，然后进行大体解剖以确定螺钉位置。
第一部分：116 枚（4.2%）螺钉前/前外侧偏位，31 枚（26.7%）毗邻重要结构。Fisher 确切检验显示，偏位 4mm 或以下的螺钉发生撞击的可能性显著降低（P<0.001）。毗邻/撞击主动脉的螺钉平均突出 5.7±0.6mm，而不涉及主动脉的螺钉平均偏位 3.9±0.2mm（P<0.001）。第二部分：共置入 285 枚螺钉，其中 125 枚在 CT 扫描时偏位至前路/前外侧，大体解剖发现 89 枚螺钉明显偏位，23 枚虽完全被软组织覆盖但可触及，13 枚被骨包裹。所有 23 枚螺钉均未危及任何结构，在 CT 扫描上突出小于 4mm。
CT 扫描时前路/前外侧偏位 4mm 或以下不会显著增加撞击风险，因此可认为是安全的。
3 级。
