Petilon Julio, Hardenbrook Mitchell, Sukovich William
Medical Corps, United States Navy, Portsmouth, Virginia, USA.
J Spinal Disord Tech. 2008 Aug;21(6):422-9. doi: 10.1097/BSD.0b013e31815708a6.
Fluoroscopy imaging evaluation for total disc arthroplasty.
To describe the effect of fluoroscopic parallax on the relative position of the Charité and identify the most reliable method for evaluating intraoperative disc position.
Results of the Investigational Device Exemption study revealed that clinical outcomes of the Charité artificial disc correlated with accurate placement of the prosthesis. This is the first study to quantitatively evaluate the technique of intraoperative fluoroscopy during positioning of an artificial lumbar disc.
A Charité artificial disc (DePuy Spine, Raynham, MA) was implanted at the L5-S1 disc space of a radiopaque lumbar spine model in ideal position. A true anteroposterior fluoroscopic image of the L5-S1 disc space was obtained as were additional images as the central ray was moved to the left and right in 1 cm increments and with rotation at 1, 2, and 3 degrees. Images were also evaluated on a poorly placed and minimally displaced disc. Measurements of the distances from the middle tooth of the endplates to the anatomic center (spinous process) and alternative measurements for evaluating disc position were examined from computer-enhanced images.
An ideally placed prosthesis appeared more displaced with increasing rotation and distance of the C-arm away from center when the spinous process was used as the midline reference. As little as 3 degrees of rotation of the fluoroscopic ray from the true anteroposterior image, made an ideally placed disc appear in poor position. Conversely, a poorly placed disc seemed to be in ideal position. Calculated displacement using measurements off the vertebral bodies remained more constant. Calculated displacement of an ideally placed prosthesis fell within 2 mm whereas all poorly placed discs had calculated differences greater than 4 mm.
The spinous process is an unreliable anatomic midline marker. In contrast, the borders of the vertebral bodies can more reliably be used to calculate the displacement of the prosthesis from centerline to determine prosthesis position. Fluoroscopic parallax can cause an ideally placed prosthesis to appear more displaced with increasing rotation and distance away from the true anteroposterior image. The spinous process was determined to be an unreliable midline marker. The vertebral borders provided a more dependable anatomic reference point to establish the disc-space midline.
全椎间盘置换术的荧光透视成像评估
描述荧光透视视差对Charité假体相对位置的影响，并确定评估术中椎间盘位置的最可靠方法。
研究器械豁免研究结果显示，Charité人工椎间盘的临床疗效与假体的准确放置相关。这是第一项在人工腰椎间盘定位过程中对术中荧光透视技术进行定量评估的研究。
将一枚Charité人工椎间盘（DePuy Spine公司，雷纳姆，马萨诸塞州）植入不透射线的腰椎模型的L5-S1椎间盘间隙的理想位置。获取L5-S1椎间盘间隙的真实前后位荧光透视图像，以及当中心射线以1厘米的增量向左和向右移动并分别旋转1度、2度和3度时的额外图像。还对位置不佳和移位最小的椎间盘的图像进行了评估。从计算机增强图像中检查终板中间齿到解剖中心（棘突）的距离测量以及用于评估椎间盘位置的替代测量。
当以棘突作为中线参考时，随着C形臂旋转角度增加以及远离中心的距离增大，位置理想的假体看起来移位更大。荧光透视射线相对于真实前后位图像仅旋转3度，就会使位置理想的椎间盘看起来位置不佳。相反，位置不佳的椎间盘似乎处于理想位置。使用椎体测量计算出的移位更恒定。位置理想的假体计算出的移位在2毫米以内而所有位置不佳的椎间盘计算出的差异大于4毫米。
棘突是不可靠的解剖学中线标记。相比之下，椎体边界可更可靠地用于计算假体从中心线的移位以确定假体位置。荧光透视视差可导致位置理想的假体随着旋转角度增加和远离真实前后位图像而看起来移位更大。棘突被确定为不可靠的中线标记。椎体边界为确定椎间盘间隙中线提供了更可靠的解剖学参考点。
