Park Daniel K, Rhee John M, Kim Sung S, Enyo Yoshio, Yoshiok Katsuhito
*Department of Orthopedic Surgery, William Beaumont Hospital, Royal Oak, MI †Department of Orthopedic Surgery, Emory Spine Center, Emory University, Atlanta, GA ‡Department of Orthopedic Surgery, Seoul Spine Institute, Inje University Sanggye-Paik Hospital, Seoul, Korea §Department of Orthopedic Surgery, Wakayama Medical University, Wakayama, Japan.
J Spinal Disord Tech. 2015 Mar;28(2):41-6. doi: 10.1097/BSD.0b013e31829a37ac.
This study is a radiographic analysis.
To compare the fusion rates after anterior cervical discectomy and fusion (ACDF) using x-rays versus computerized tomography (CT).
Although fusion status may be obvious when evaluating ACDFs performed in the remote past, determining the presence of a solid fusion at earlier time points after ACDF is often ambiguous but a necessary part of practice. Commonly used tools include radiographs and CT scans. Currently, there is no gold standard imaging modality to determine fusion status.
Twenty-two patients status post-ACDF (cortical allograft with anterior plates) at 34 levels with CT scans and dynamic x-rays obtained at 3, 6, and 12 months postoperatively were included. Four spine surgeons blinded to the time point independently determined fusion status according to the criteria.
On the basis of the x-ray criteria, the fusion rates were 26%, 41%, and 65% at 3, 6, and 12 months, respectively, postoperatively. On the basis of CT criteria, the fusion rates were 79%, 79%, and 91% at 3, 6, and 12 months, respectively. There was a significant difference in the predicted fusion rate at each time point comparing x-ray versus CT criteria. In addition, at 3 months, 41% of the levels (11/27) thought to be fused by CT criteria demonstrated >1 mm motion on dynamic x-rays. At 6 months, 33% (9/27) of the levels thought to be fused by CT demonstrated persistent motion of ≥1 mm. At 12 months, 23% (7/31) of the levels considered fused by CT still had persistent motion.
X-ray criteria for fusion, which incorporate both static and dynamic factors, predicted lower fusion rates at each time point when compared with CT scans, which evaluate only static factors. Depending on the time point, anywhere from 23% to 41% of levels thought to be fused by CT criteria demonstrated persistent motion on dynamic x-rays. Although <1 mm motion is not a sufficient criteria for fusion by itself, levels demonstrating >1 mm motion are less likely to be solidly fused. Thus, we conclude that CT scans may overestimate the fusion rate during the early stages of ACDF healing with cortical allograft, and that CT scans alone may not accurately determine fusion status. Reliable determination of fusion may thus require dynamic information obtained from flexion-extension x-ray in association with high-resolution static information from CT.
本研究为影像学分析。
比较颈椎前路椎间盘切除融合术（ACDF）后使用X线与计算机断层扫描（CT）评估的融合率。
虽然在评估既往进行的ACDF时融合状态可能很明显，但在ACDF术后早期确定是否存在牢固融合往往不明确，但这是临床实践中必要的一部分。常用的工具包括X线片和CT扫描。目前，尚无确定融合状态的金标准成像方式。
纳入22例行ACDF术后（使用皮质骨同种异体移植并前路钢板固定）的患者，共34个节段，术后3、6和12个月均有CT扫描及动态X线片。4名对时间点不知情的脊柱外科医生根据标准独立确定融合状态。
根据X线标准，术后3、6和12个月的融合率分别为26%、41%和65%。根据CT标准，术后3、6和12个月的融合率分别为79%、79%和91%。比较X线与CT标准，各时间点预测的融合率存在显著差异。此外，在3个月时，根据CT标准认为已融合的节段中有41%（11/27）在动态X线片上显示运动超过1mm。在6个月时，根据CT标准认为已融合的节段中有33%（9/27）显示持续运动≥1mm。在12个月时，根据CT标准认为已融合的节段中有23%（7/31）仍有持续运动。
融合的X线标准纳入了静态和动态因素，与仅评估静态因素的CT扫描相比，在各时间点预测的融合率较低。根据时间点不同，根据CT标准认为已融合的节段中有23%至41%在动态X线片上显示持续运动。虽然<1mm的运动本身并非融合的充分标准，但运动超过1mm的节段牢固融合的可能性较小。因此，我们得出结论，在使用皮质骨同种异体移植的ACDF愈合早期，CT扫描可能高估了融合率，且仅CT扫描可能无法准确确定融合状态。可靠地确定融合可能需要从屈伸位X线片获得的动态信息以及来自CT的高分辨率静态信息。
