Department of Orthopaedic Surgery, Duke University Medical Center, Durham, NC, USA.
Foot Ankle Int. 2013 Dec;34(12):1624-8. doi: 10.1177/1071100713505534. Epub 2013 Sep 16.
The majority of total ankle arthroplasty (TAA) systems use extramedullary alignment guides for tibial component placement. However, at least 1 system offers intramedullary referencing. In total knee arthroplasty, studies suggest that tibial component placement is more accurate with intramedullary referencing. The purpose of this study was to compare the accuracy of extramedullary referencing with intramedullary referencing for tibial component placement in total ankle arthroplasty.
The coronal and sagittal tibial component alignment was evaluated on the postoperative weight-bearing anteroposterior (AP) and lateral radiographs of 236 consecutive fixed-bearing TAAs. Radiographs were measured blindly by 2 investigators. The postoperative alignment of the prosthesis was compared with the surgeon's intended alignment in both planes. The accuracy of tibial component alignment was compared between the extramedullary and intramedullary referencing techniques using unpaired t tests. Interrater and intrarater reliabilities were assessed with intraclass correlation coefficients (ICCs).
Eighty-three tibial components placed with an extramedullary referencing technique were compared with 153 implants placed with an intramedullary referencing technique. The accuracy of the extramedullary referencing was within a mean of 1.5 ± 1.4 degrees and 4.1 ± 2.9 degrees in the coronal and sagittal planes, respectively. The accuracy of intramedullary referencing was within a mean of 1.4 ± 1.1 degrees and 2.5 ± 1.8 degrees in the coronal and sagittal planes, respectively. There was a significant difference (P < .001) between the 2 techniques with respect to the sagittal plane alignment. Interrater ICCs for coronal and sagittal alignment were high (0.81 and 0.94, respectively). Intrarater ICCs for coronal and sagittal alignment were high for both investigators.
Initial sagittal plane tibial component alignment was notably more accurate when intramedullary referencing was used. Further studies are needed to determine the effect of this difference on clinical outcomes and long-term survivability of the implants.
Level III, retrospective comparative study.
大多数全踝关节置换术（TAA）系统使用髓外定位导向器来放置胫骨组件。然而，至少有一个系统提供髓内参考。在全膝关节置换术中，研究表明髓内参考可使胫骨组件的放置更准确。本研究的目的是比较髓外参考与髓内参考在全踝关节置换术中胫骨组件放置的准确性。
对 236 例连续固定轴承 TAA 的术后负重前后位（AP）和侧位 X 线片进行冠状面和矢状面胫骨组件对线的评估。由 2 名研究者进行盲法测量。术后假体的对线与术中计划的对线在两个平面上进行比较。使用配对 t 检验比较髓外和髓内参考技术的胫骨组件对线准确性。采用组内相关系数（ICC）评估组内和组间的可靠性。
83 个胫骨组件采用髓外参考技术放置，153 个胫骨组件采用髓内参考技术放置。髓外参考的准确性在冠状面和矢状面分别为平均 1.5°±1.4°和 4.1°±2.9°。髓内参考的准确性在冠状面和矢状面分别为平均 1.4°±1.1°和 2.5°±1.8°。两种技术在矢状面的对线差异有统计学意义（P<0.001）。冠状面和矢状面的组内相关系数均较高（分别为 0.81 和 0.94）。两名观察者的冠状面和矢状面的组内相关系数均较高。
当使用髓内参考时，初始矢状面胫骨组件对线明显更准确。需要进一步研究以确定这种差异对临床结果和植入物的长期存活率的影响。
III 级，回顾性比较研究。
