Sarwahi Vishal, Ayan Saankritya, Amaral Terry, Wendolowski Stephen, Gecelter Rachel, Lo Yungtai, Thornhill Beverly
Department of Pediatric Orthopaedics, Cohen Children's Medical Center, Northwell Health System, New Hyde Park, NY, USA.
Department of Orthopaedic Surgery, Montefiore Medical Center, Bronx, NY, USA.
Spine Deform. 2017 Mar;5(2):109-116. doi: 10.1016/j.jspd.2016.10.007.
Retrospective case series.
The objective of this study was to determine the safety of postoperative radiographs to assess screw placement.
Previously defined criteria are frequently employed to determine pedicle screw placement on intraoperative supine radiographs. Postoperatively, radiographs are typically used as a precursor to identify screws of concern, and a computed tomographic (CT) is typically ordered to confirm screw safety.
First, available postoperative PA and lateral radiographs were reviewed by 6 independently blinded observers. Screw misplacement was assessed using previously defined criteria. A musculoskeletal radiologist assessed all CT scans for screw placement. Pedicle screw position was classified either as acceptable or misplaced. Misplacements were subclassified as medial, lateral, or anterior.
One hundred four patients with scoliosis or kyphosis underwent posterior spinal fusion and had postoperative CT scan available were included. In total, 2,034 thoracic and lumbar screws were evaluated. On CT scan, 1,772 screws were found to be acceptable, 142 were laterally misplaced, 30 medially, and 90 anteriorly. Of the 30 medially placed screws, 80% to 87% screws were believed to be in positions other than medial, with a median of 73% (63% to 92%) of these screws presumed to be in normal position. Similarly, of the 142 screws placed laterally, 49% to 81% screws were identified in positions other than lateral, with a median of 77% (59% to 96%) of these screws felt to be in normal position. Of the 90 anteriorly misplaced screws, 16% to 87% screws were identified in positions other than anterior, with 72% (20% to 98%) identified as normal. The criteria produced a median 52% sensitivity, 70% specificity, and 68% accuracy across the 6 observers.
Radiograph is a poor diagnostic modality for observing screw position.
Level IV.
回顾性病例系列研究。
本研究的目的是确定术后X线片评估螺钉置入安全性的情况。
先前定义的标准常被用于术中仰卧位X线片上确定椎弓根螺钉的置入位置。术后，X线片通常作为识别可疑螺钉的前期检查手段，通常还会要求进行计算机断层扫描（CT）以确认螺钉的安全性。
首先，6名独立的盲法观察者对现有的术后正位和侧位X线片进行评估。使用先前定义的标准评估螺钉位置不当情况。一名肌肉骨骼放射科医生评估所有CT扫描的螺钉置入情况。椎弓根螺钉位置分为可接受或位置不当。位置不当进一步细分为内侧、外侧或前方。
纳入104例患有脊柱侧弯或后凸畸形且术后有CT扫描资料的患者。总共评估了2034枚胸腰椎螺钉。在CT扫描中，发现1772枚螺钉位置可接受，142枚外侧位置不当，30枚内侧位置不当，90枚前方位置不当。在30枚内侧位置不当的螺钉中，80%至87%的螺钉被认为处于非内侧位置，这些螺钉中，中位值为73%（63%至92%）的螺钉被推测处于正常位置。同样，在142枚外侧位置不当的螺钉中，49%至81%的螺钉被识别为处于非外侧位置，这些螺钉中，中位值为77%（59%至96%）的螺钉被认为处于正常位置。在90枚前方位置不当的螺钉中，16%至87%的螺钉被识别为处于非前方位置，72%（20%至98%）被识别为正常。这些标准在6名观察者中产生的中位敏感性为52%，特异性为70%，准确性为68%。
X线片对于观察螺钉位置是一种较差的诊断方式。
四级。
