University of Ulm, Helmholzstraße 16, 89081, Ulm, Germany.
Mayo Clinic Health System in Eau Claire, Luther Campus Clinic, 1400 Bellinger Street, Eau Claire, WI, 54703, USA.
Knee Surg Sports Traumatol Arthrosc. 2018 Nov;26(11):3219-3229. doi: 10.1007/s00167-018-4836-3. Epub 2018 Jan 25.
The purpose of the present study is to compare newer designs of various symmetric and asymmetric tibial components and measure tibial bone coverage using the rotational safe zone defined by two commonly utilized anatomic rotational landmarks.
Computed tomography scans (CT scans) of one hundred consecutive patients scheduled for total knee arthroplasty were obtained pre-operatively. A virtual proximal tibial cut was performed and two commonly used rotational axes were added for each image: the medio-lateral axis (ML-axis) and the medial 1/3 tibial tubercle axis (med-1/3-axis). Different symmetric and asymmetric implant designs were then superimposed in various rotational positions for best cancellous and cortical coverage. The images were imported to a public domain imaging software, and cancellous and cortical bone coverage was computed for each image, with each implant design in various rotational positions.
One single implant type could not be identified that provided the best cortical and cancellous coverage of the tibia, irrespective of using the med-1/3-axis or the ML-axis for rotational alignment. However, it could be confirmed that the best bone coverage was dependent on the selected rotational landmark. Furthermore, improved bone coverage was observed when tibial implant positions were optimized between the two rotational axes.
Tibial coverage is similar for symmetric and asymmetric designs, but depends on the rotational landmark for which the implant is designed. The surgeon has the option to improve tibial coverage by optimizing placement between the two anatomic rotational alignment landmarks, the medial 1/3 and the ML-axis. Surgeons should be careful assessing intraoperative rotational tibial placement using the described anatomic rotational landmarks to optimize tibial bony coverage without compromising patella tracking.
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本研究的目的是比较各种对称和非对称胫骨组件的新设计，并使用两个常用解剖旋转标志定义的旋转安全区来测量胫骨骨覆盖。
我们获得了 100 例计划行全膝关节置换术的连续患者的术前计算机断层扫描（CT）扫描。对虚拟的胫骨近端进行截骨，并为每个图像添加两个常用的旋转轴：横向（ML 轴）和内侧 1/3 胫骨结节轴（med-1/3 轴）。然后，根据最佳松质骨和皮质骨覆盖的需要，将不同的对称和非对称植入物设计叠加在各种旋转位置上。将图像导入公共域成像软件，并为每个图像计算不同旋转位置的每个植入物设计的松质骨和皮质骨覆盖。
无论使用 med-1/3 轴还是 ML 轴进行旋转对线，都无法确定一种单一的植入物类型可以提供最佳的胫骨皮质和松质骨覆盖。然而，可以确认最佳的骨覆盖取决于所选的旋转标志。此外，当在两个旋转轴之间优化胫骨植入物位置时，观察到骨覆盖的改善。
对称和非对称设计的胫骨覆盖相似，但取决于植入物设计的旋转标志。外科医生可以通过在两个解剖旋转对线标志（内侧 1/3 和 ML 轴）之间优化植入物位置来改善胫骨覆盖，而不会影响髌骨轨迹。外科医生应该小心评估术中旋转胫骨位置，使用描述的解剖旋转标志来优化胫骨骨覆盖，而不会损害髌骨轨迹。
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