Zhang Xingkai, Ordway Nathaniel R, Tan Rong, Rim Byeong Cheol, Fayyazi Amir H
Shanghai Jiaotong University Medical College Ruijin Hospital, Shanghai Institute of Orthopedics and Traumatology, Shanghai, China.
J Spinal Disord Tech. 2008 Aug;21(6):400-5. doi: 10.1097/BSD.0b013e318157d382.
This study was designed to evaluate the effectiveness of preoperative computed tomography (CT) scan in predicting endplate strength.
To demonstrate a correlation between the cervical trabecular bone density and the failure strength of the endplate.
Cervical total disc arthroplasty devices have to transmit the force to the endplate for the remainder of the patients' life. One potential complication at this interface is endplate fracture and implant subsidence, which usually occurs early postoperatively and may be related to weakness of the boney endplate.
Six fresh human cadaver cervical spines were harvested and scanned for the determination of trabecular density using a peripheral quantitative CT (QCT) scanner. The specimens were then disarticulated and the inferior endplate of each vertebral segment was biomechanically tested using a 2-mm indentation probe to determine average endplate strength. The superior endplate of each vertebral body was then fitted with the appropriately sized ProDisc-C endplate and biomechanically tested until failure. Regression analyses were used to compare the interface failure stress of the implant with the bone mineral content and the average endplate stress as measured with the indentation probe.
The average bone mineral content of the specimens was 322+/-57 mg/cm. The average endplate strength and stress measured by the indentation test was 176+/-129 N and 56+/-34 N/mm, respectively. The average ProDisc-C/endplate failure load and failure stress were 1875+/-1023 N and 10.2+/-4.1 N/mm, respectively. There was a direct correlation between the ProDisc-C/endplate failure stress and the bone mineral content measured by peripheral QCT (R=0.48, P<0.01). There was also a significant correlation between ProDisc-C/endplate failure stress and the endplate indentation stress.
This study demonstrates the utility of a preoperative QCT scan in predicting the failure stress of the cervical endplate before total disc replacement. This information may potentially decrease early complications of device subsidence or endplate fracture.
本研究旨在评估术前计算机断层扫描（CT）在预测终板强度方面的有效性。
证明颈椎小梁骨密度与终板破坏强度之间的相关性。
颈椎全椎间盘置换装置必须在患者余生中将力传递至终板。该界面的一个潜在并发症是终板骨折和植入物下沉，这通常发生在术后早期，可能与骨终板薄弱有关。
采集6具新鲜人尸体颈椎，使用外周定量CT（QCT）扫描仪进行扫描以测定小梁密度。然后将标本分离，使用2毫米压痕探针对每个椎体节段的下终板进行生物力学测试，以确定平均终板强度。然后在每个椎体的上终板安装尺寸合适的ProDisc-C终板，并进行生物力学测试直至失效。使用回归分析比较植入物的界面破坏应力与骨矿物质含量以及用压痕探针测量的平均终板应力。
标本的平均骨矿物质含量为322±57毫克/立方厘米。压痕试验测得的平均终板强度和应力分别为176±129牛和56±34牛/平方毫米。ProDisc-C/终板的平均失效载荷和失效应力分别为1875±1023牛和10.2±4.1牛/平方毫米。ProDisc-C/终板失效应力与外周QCT测量的骨矿物质含量之间存在直接相关性（R = 0.48，P < 0.01）。ProDisc-C/终板失效应力与终板压痕应力之间也存在显著相关性。
本研究证明了术前QCT扫描在预测全椎间盘置换术前颈椎终板破坏应力方面的实用性。该信息可能会降低装置下沉或终板骨折的早期并发症。
