Nantawat Raksamani, MD¹ , Attaporn Piyaphanee, MD¹, Montri Wattanakaewsripetch, MD¹

Background: In Asian populations, proximal tibial vara is mostly present. The tibial cut referenced from the center of the intercondylar eminence to the center of the ankle often leads to varus malalignment.

Objective: To evaluate the effect of lateralizing the tibial reference point on the coronal plane alignment in postoperative radiographic evaluation.

Materials and Methods: In this retrospective study, radiographs of 41 patients (79 knees) with primary osteoarthritis with proximal tibial vara underwent primary total knee arthroplasty (TKA) between May 2017 and April 2024. The tibial alignment of 40 knees used a conventional landmark with a proximal tibial reference point at the center of the intercondylar eminence, and 39 knees used a lateralized proximal tibial reference point from the individual pre-operative radiographs. The postoperative medial proximal tibial angle (MPTA) of both groups were compared with the chisquare and Odds ratio. The lateralized distance between the tibial reference point and the center of the intercondylar eminence was measured in the lateralized tibial alignment group. The degree of correlation between the magnitude of tibia vara and the lateralized distance of the proximal tibial reference point was analyzed using linear regression analysis.

Results: The MPTA outlier over 3 degrees found 9 knees in the conventional tibial alignment method and 2 knees in the lateralized tibial alignment method of TKA. A significant interaction was found (chi-square 4.972, p=0.026, odds ratio 5.371). The mean lateralized distance of the proximal tibial reference point was 6.17 mm (SD 1.58). There was a strong correlation between the magnitude of the tibial vara and the lateralized distance of the proximal tibial reference point (R²=0.751, p<0.001).

Conclusion: TKA in patients with osteoarthritis of the knee with proximal tibia vara can use the lateralized proximal tibial reference point for tibial alignment to increase the acceptable coronal alignment of the tibial prosthesis. The proximal tibial vara angle had a high degree of positive correlation with the lateralized distance of the proximal tibial reference point.

Received 2 October 2025 | Revised 18 February 2026 | Accepted 22 February 2026

J Med Assoc Thai 2026;109(7):597-603

DOI: 10.35755/jmedassocthai.2026.7.03288