Accuracy assessment of measuring component position after total ankle arthroplasty using a conventional method

Table 2 Accuracy of implant position after total ankle arthroplasty according to preoperative deformity

	Preoperative coronal alignment^a					Preoperative sagittal alignment^b
	Varus (n = 80)	Neutral (n = 42)	Valgus (n = 28)	p value		Extension (n = 85)	Neutral (n = 58)	Flexion (n = 7)	p value
α angle^a	92.4 ± 2.7	91.6 ± 2.4	90.7 ± 2.8	0.061	β angle^a	84.5 ± 3.8	84.6 ± 2.8	83.8 ± 1.3	0.808
Outcomes^b					Outcomes^b
Excellent	41 (51.2%)	30 (71.5%)	15 (53.6%)	0.244	Excellent	52 (61.2%)	41 (70.7%)	5 (71.4%)	0.769
Acceptable	28 (35.0%)	9 (21.4%)	11 (39.3%)		Acceptable	23 (27.0%)	12 (20.7%)	2 (28.6%)
Outlier	11 (13.8%)	3 (7.1%)	2 (7.1%)		Outlier	10 (11.8%)	5 (8.6%)	–
γ angle^a	91.9 ± 3.3	91.2 ± 2.9	90.2 ± 2.6	0.286	δ angle^a	91.4 ± 3.9	91.3 ± 4.2	90.4 ± 6.0	0.225
Outcomes^b					Outcomes^b
Excellent	43 (53.8%)	29 (69.1%)	18 (64.3%)	0.385	Excellent	45 (52.9%)	29 (50.0%)	2 (28.6%)	0.584
Acceptable	26 (32.4%)	10 (23.8%)	9 (32.1%)		Acceptable	25 (29.4%)	18 (31.0%)	2 (28.6%)
Outlier	11 (13.8%)	3 (7.1%)	1 (3.6%)		Outlier	15 (17.7%)	11 (19.0%)	3 (42.8%)

^aValues are given as the mean and the standard deviation
^bValues are given as the number of ankles with the percentage in parentheses
Neutral is within 5° of tibiotalar angle on anteroposterior radiograph. Varus and valgus ankles are defined as those greater than 5° from optimal values
Neutral is within 5° of extension and flexion on lateral radiograph. Extension and flexion ankles are defined as those greater than 5° from optimal values
The ideal value of α, γ, and δ angle is 90°, that of β angle is 84°. Outcome was defined as “excellent” when values were within 3°, “acceptable” when within 5°, and as “outlier” when more than 5° from optimum value. Outcome values are shown as percentage with the number of ankles in parentheses

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