Senior Department of Orthopedics, the Fourth Medical Center of PLA General Hospital, Beijing, People's Republic of China.
School of Medicine, Nankai University, Tianjin, People's Republic of China.
J Bone Joint Surg Am. 2023 Sep 6;105(17):1338-1343. doi: 10.2106/JBJS.23.00076. Epub 2023 Jul 6.
Sagittal alignment determines the extension and flexion of knee prostheses in total knee arthroplasty (TKA). The definition of the sagittal axes may be different between the Mako TKA system (Stryker) and the conventional manual intramedullary approach. Whether there is any discrepancy between the 2 approaches has not been well studied.
We retrospectively analyzed 60 full-length computed tomographic (CT) scans of the lower extremities of 54 patients. The femur and tibia were modeled by using Mimics (Materialise). The Mako mechanical axes were determined according to the Mako TKA Surgical Guide. The manual intramedullary axes were determined according to the central axis of the tibial proximal and femoral distal medullary cavities. The femoral, tibial, and combined angular discrepancies were measured in the sagittal plane.
On the femoral side, the Mako mechanical axis was more likely to be located in an extended position relative to the manual intramedullary axis (56 of 60 knees). The median angular discrepancy was 2.46° (interquartile range [IQR], 1.56° to 3.43° [range, -1.06° to 5.24°]). On the tibial side, the Mako mechanical axis was likely to be located in a flexed position relative to the manual intramedullary axis (57 of 60 knees). The median angular discrepancy was 2.40° (IQR, 1.87° to 2.84° [range, -0.79° to 4.20°]). The angular discrepancy of the femoral-tibial sagittal angle was 4.63° (IQR, 3.71° to 5.64° [range, 1.20° to 9.02°]).
Compared with manual TKA, the Mako system is more likely to result in a decreased posterior tibial slope and extension of the femoral prosthesis. It may also influence the evaluation of lower-extremity extension and flexion. When using the Mako system, special attention should be given to these discrepancies.
Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.
在全膝关节置换术（TKA）中，矢状面对线决定了膝关节假体的屈伸。Mako TKA 系统（Stryker）和传统的髓内手动入路之间，矢状轴的定义可能不同。这两种方法之间是否存在差异尚未得到很好的研究。
我们回顾性分析了 54 例患者的 60 例下肢全长 CT 扫描。使用 Mimics（Materialise）对股骨和胫骨进行建模。Mako 机械轴根据 Mako TKA 手术导板确定。髓内手动轴根据胫骨近端和股骨远端髓腔的中心轴确定。在矢状面测量股骨、胫骨和联合角偏差。
在股骨侧，Mako 机械轴相对于髓内手动轴更倾向于位于伸展位置（60 膝中的 56 膝）。中位角度偏差为 2.46°（四分位距[IQR]，1.56°至 3.43°[范围，-1.06°至 5.24°]）。在胫骨侧，Mako 机械轴相对于髓内手动轴更倾向于位于弯曲位置（60 膝中的 57 膝）。中位角度偏差为 2.40°（IQR，1.87°至 2.84°[范围，-0.79°至 4.20°]）。股骨-胫骨矢状角的角度偏差为 4.63°（IQR，3.71°至 5.64°[范围，1.20°至 9.02°]）。
与手动 TKA 相比，Mako 系统更有可能导致胫骨后倾减小和股骨假体的伸展。它还可能影响下肢伸展和屈曲的评估。使用 Mako 系统时，应特别注意这些差异。
治疗水平 IV。有关证据水平的完整描述，请参见作者说明。
