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Table 3 Classification of the coronal alignment based on HKA and FTA

From: Using short knee radiographs to predict the coronal alignment after TKA: Is it an accurate proxy for HKA on full-length images?

HKA

Varus

Neutral

Valgus

Agreement rate (%)

P value

FTA calculated in this study

 Varus (FTA < 3.7°)

102

10

–

79.8

0.54

 Neutral (3.7° ≤ FTA ≤ 9.5°)

24

70

8

  

 Valgus (FTA > 9.5°)

–

3

6

  

FTA reported by Morgan

 Varus (FTA < 4°)

107

11

–

82.5

 

 Neutral (4° ≤ FTA ≤ 9°)

19

68

5

  

 Valgus (FTA > 9°)

–

4

9

  

FTA reported by Kim

 Varus (FTA < 3°)

85

7

–

72.2

0.013

 Neutral (3° ≤ FTA ≤ 7.5°)

41

65

3

  

 Valgus (FTA > 7.5°)

–

11

11

  

FTA reported by Ritter

 Varus (FTA < 2.4°)

74

4

–

68.2

0.0006

 Neutral (2.4° ≤ FTA ≤ 7.2°)

52

66

2

  

 Valgus (FTA > 7.2°)

–

12

12

  
  1. HKA hip-knee-ankle angle, FTA femorotibial angle