Anterior tibial curved cortex is a reliable landmark for tibial rotational alignment in total knee arthroplasty

ABSTRACT Purpose We hypothesized that the anterior tibial surface curvature is a more reliable landmark for correct tibial component rotational positioning in TKA respect to the ‘Akagi’ line and the medial third of the tibial tubercle. Methods Three independent investigators reviewed 124 knee MRI scans, identifying independently the femoral transepicondylar axis (TEA), the femoral posterior condylar axis (PCA), a line connecting the middle of the posterior cruciate ligament and the medial edge of the patellar tendon attachment (Akagi's line), the medial third of the tibial tubercle and the anterior tibial surface curvature. The most appropriate tibial baseplate tracing for the NexGen Total Knee System (Zimmer, Warsaw, USA) was superimposed matching the anterior tibial cortex with its anterior surface. At this point, the rotation of the tibial plate tracing was calculated in respect to the TEA, the medial third of the tibial tubercle line, the Akagi's line and the PCA. Customized software was created and used for analysis of the MRI datasets. Results: The investigators agreed on the localization of the Akagi's line in 64% of the cases within 3° and in 85% of the cases within 5° (minimum –16°, maximum –7°): this landmark might lead to internal rotation of the tibial component. The observers agreed on the localization of the medial third of the tibial tubercle in 29% of the cases within 3° and, in 70% of the cases, within 5° (minimum –4°, maximum +4°): this landmark might lead to external rotation of the tibial component. The investigators agreed on the localization of the anterior tibial surface curvature in 89% of the cases within 3° and in 99% of the cases within 5° (minimum –1°, maximum +4°): component alignment along the anterior cortex guaranteed full matching ±3° to the epicondylar axis in 75% of the knees. Conclusion Alignment of the tibial component, when based on the anterior tibial surface, was more reliable and easier identifiable than either the Akagi's line or the medial third of the tibial tubercle. Level of evidence Level 3 (Retrospective cohort study). Indelli PF, Baldini A, Manfredini L, Marcucci M. Rotational Alignment Landmarks in Primary Total Knee Arthroplasty. The Duke Orthop J 2014;4(1):8-12.

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The Adjustment of the Rotational Alignment of the Distal End of the Extramedullary Guide to the Anteroposterior Axis of the Proximal Tibia in Total Knee Arthroplasty

The Journal of Knee Surgery ◽

10.1055/s-0040-1722660 ◽

2021 ◽

Author(s):

Hideki Mizu-uchi ◽

Hidehiko Kido ◽

Tomonao Chikama ◽

Kenta Kamo ◽

Satoshi Kido ◽

...

Keyword(s):

Total Knee Arthroplasty ◽

Knee Arthroplasty ◽

Navigation System ◽

Proximal Tibia ◽

Rotational Alignment ◽

Coronal Alignment ◽

Ideal Position ◽

Total Knee ◽

Alignment Guide ◽

The Ideal

AbstractThe optimal placement within 3 degrees in coronal alignment was reportedly achieved in only 60 to 80% of patients when using an extramedullary alignment guide for the tibial side in total knee arthroplasty (TKA). This probably occurs because the extramedullary alignment guide is easily affected by the position of the ankle joint which is difficult to define by tibial torsion. Rotational direction of distal end of the extramedullary guide should be aligned to the anteroposterior (AP) axis of the proximal tibia to acquire optimal coronal alignment in the computer simulation studies; however, its efficacy has not been proven in a clinical setting. The distal end of the guide can be overly displaced from the ideal position when using a conventional guide system despite the alignment of the AP axis to the proximal tibia. This study investigated the effect of displacement of the distal end of extramedullary guide relative to the tibial coronal alignment while adjusting the rotational alignment of the distal end to the AP axis of the proximal tibia in TKA. A total of 50 TKAs performed in 50 varus osteoarthritic knees using an image-free navigation system were included in this study. The rotational alignment of the proximal side of the guide was adjusted to the AP axis of the proximal tibia. The position of the distal end of the guide was aligned to the center of the ankle joint as viewed from the proximal AP axis (ideal position) and as determined by the navigation system. The tibial intraoperative coronal alignments were recorded as the distal end was moved from the ideal position at 3-mm intervals. The intraoperative alignments were 0.5, 0.9, and 1.4 degrees in valgus alignment with 3-, 6-, and 9-mm medial displacements, respectively. The intraoperative alignments were 0.7, 1.2, and 1.7 degrees in varus alignment with 3-, 6-, and 9-mm lateral displacements, respectively. In conclusion, the acceptable tibial coronal alignment (within 2 degrees from the optimal alignment) can be achieved, although some displacement of the distal end from the ideal position can occur after the rotational alignment of the distal end of the guide is adjusted to the AP axis of the proximal tibia.

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