More accurate component alignment in navigated total knee arthroplasty has no clinical benefit at 5-year follow-up

Figures & data

Table 1. Demographics preoperatively and postoperatively, including reoperations. Ages are mean (SD)

	Preoperatively		5 years postop.		Lost	Reoperation
	knees	age	knees	age
Image-based	26	69 (9)	24	76 (9)	2/26	4/26
p-value ^a		0.2 ^e		0.2 ^e	0.6 ^d	0.1 ^d
Image-free	29	73 (7)	28	77 (7)	1/29	1/29
p-value ^b		0.7 ^e		0.2 ^e	0.5 ^d	0.5 ^d
Conventional	31	74 (7)	28	77 (8)	3/31	2/31
p-value ^c		0.1 ^e		0.2 ^e	0.5 ^d	0.1 ^d
Total	86		80		6/86	7/86

^a Comparison between the image-based group and the image free-group.

^b Comparison between the image-free group and the conventional group.

^c Comparison between the image-based group and the conventional group.

^d Fisher’s test.

^e Mann-Whitney U test.

Table 2. Knee Society score, functional score and active range of motion preoperatively, and 2 years and 5 years postoperatively. Scores and angles are mean (SD)

	Preope- ratively	p-value ^d	2 years postop.	p-value ^e	5 years postop.	p-value ^f
Knee score (points)
Image-based	33 (14)	0.03	81 (12)	0.7	90 (13)	0.03
p-value ^a	0.4		0.5		0.6
Image-free	34 (15)	0.02	88 (4)	0.5	94 (6)	0.02
p-value ^b	0.8		0.8		0.6
Conventional	29 (14)	0.04	88 (11)	0.3	94 (12)	0.03
p-value ^c	0.3		0.5		0.2
Functional score (points)
Image-based	44 (15)	0.03	80 (16)	0.7	82 (15)	0.02
p-value ^a	0.4		0.5		0.6
Image-free	52 (16)	0.01	81 (19)	0.7	84 (14)	0.01
p-value ^b	0.5		0.4		0.6
Conventional	39 (16)	0.02	82 (22)	0.2	84 (16)	0.02
p-value ^c	0.9		0.8		0.3
Range of motion
Image-based	96° (16°)	0.1	107° (10°)	0.5	113° (8°)	0.1
range	75°–120°		85°–125°		100°–120°
p-value ^a	0.3		0.4		0.4
Image-free	100° (14°)	0.3	108° (11°)	0.5	110° (9°)	0.3
range	70–115		100°–125°		90°–120°
p-value ^b	0.3		0.6		0.2
Conventional	102° (16°)	0.3	116° (11°)	0.4	117° (7°)	0.3
range	75°–125°		95°–130°		105°–125°
p-value ^c	0.5		0.5		0.4

^a Comparison between the image-based group and the image free-group.

^b Comparison between the image-free group and the conventional group.

^c Comparison between the image-based group and the conventional group.

^d Comparison between preoperatively and 2 years postoperatively.

^e Comparison between 2 years and 5.3 years postoperatively.

^f Comparison between preoperatively and 5.3 years postoperatively.

^a–f Mann-Whitney U-test.

Table 3. Preoperative varus/valgus alignment of > 10°. Angles are mean (SD)

	Varus		Valgus		Reoperations
	n	angle	n	angle
Image-based	5	17.0° (9.6°)	4	16.3° (5.5°)	1/9
p-value ^a		0.2 ^e		0.1 ^e	0.4 ^d
Image-free	4	17.8° (4.3°)	3	18.7° (5.5°)	0/7
p-value ^b		0.4 ^e		0.1 ^e	0.2 ^d
Conventional	5	19.0° (9.6°)	4	15.3° (1.5°)	0/9
p-value ^c		0.2 ^e		0.2 ^e	0.9 ^d
Total	14		11		1/25

^a Comparison between the image-based and the image free-group.

^b Comparison between the image-free and the conventional group.

^c Comparison between the image-based and the conventional group.

^d Fisher’s exact test.

^e Mann-Whitney U-test.