Table 1 Comparison of baseline characteristics between the ‘natural’ and ‘artificial’ knee joint perception groups
|
Total
n = 60
|
Natural perception
n = 26
|
Artificial perception
n = 34
|
P Value
|
Age, years
|
74.1 ± 7.1
|
74.1 ± 7.1
|
74.1 ± 7.3
|
.884
|
Male, n (%)
|
10 (16.7)
|
4 (15.4)
|
6 (17.6)
|
.816
|
Body mass index, kg/m2
|
24.9 ± 3.0
|
24.4 ± 3.3
|
25.3 ± 3.2
|
.745
|
Follow-up duration, years
|
2.6 ± 1.3
|
2.5 ± 1.0
|
2.7 ± 1.1
|
.873
|
Kellgren-Lawrence classification, n
|
|
|
|
|
Garde II: III: IV
|
2 :18: 40
|
1: 9: 16
|
1: 16: 17
|
.625
|
Charlson Comorbidity Index, n (%)
|
|
|
|
.998
|
0
|
21 (35.0)
|
9 (34.6)
|
12 (35.3)
|
|
1 – 2
|
32 (53.3)
|
14 (53.8)
|
18 (52.9)
|
|
3+
|
7 (11.7)
|
3 (11.5)
|
4 (11.8)
|
|
Knee extension angle, degrees
|
-10.5 ± 8.3
|
-10.1 ± 7.6
|
-10.8 ± 8.5
|
.846
|
Knee flexion angle, degrees
|
116.4 ± 15.2
|
117.1 ± 15.3
|
115.9 ± 15.1
|
.772
|
Knee score, points
|
50.8 ± 13.2
|
51.2 ± 12.3
|
50.5 ± 13.6
|
.537
|
Functional score, points
|
48.6 ± 21.9
|
49.2 ± 21.3
|
48.1 ± 20.5
|
.473
|
Hip knee ankle angle, degrees
|
9.8 varus ± 4.2
|
9.7 varus ± 4.1
|
9.9 varus ± 4.5
|
.671
|
Data are expressed as the mean ± standard deviation or count (%) as appropriate for the data type.
A P-value < .05 is indicative of a significant between-group difference.
Table 2 Between-group comparisons of intraoperative soft tissue balance measures
|
Distraction force, lbf
|
Natural perception
|
Artificial perception
|
P Value
|
Extension gap, mm
|
5
|
7.45 ± 0.91
|
7.49 ± 0.92
|
.875
|
|
10
|
8.25 ± 1.03
|
8.21 ± 1.04
|
.474
|
|
20
|
9.63 ± 1.51
|
9.70 ± 1.46
|
.376
|
|
30
|
11.22 ± 2.02
|
11.23 ± 2.03
|
.762
|
|
40
|
12.64 ± 2.48
|
12.70 ± 2.52
|
.881
|
Flexion gap, mm
|
5
|
7.90 ± 1.41
|
7.94 ± 1.43
|
.173
|
|
10
|
8.73 ± 1.71
|
8.72 ± 1.74
|
.536
|
|
20
|
11.22 ± 2.19 *
|
10.46 ± 2.22
|
.041
|
|
30
|
12.10 ± 2.79
|
11.53 ± 2.81
|
.372
|
|
40
|
13.83 ± 3.41
|
13.56 ± 3.43
|
.793
|
Gap difference, mm
|
5
|
0.45 ± 1.01
|
0.45 ± 1.04
|
.556
|
|
10
|
0.48 ± 1.11
|
0.51 ± 1.12
|
.648
|
|
20
|
1.59 ± 1.32 *
|
0.76 ± 1.35
|
<.001
|
|
30
|
0.88 ± 1.59 *
|
0.30 ± 1.64 *
|
.022
|
|
40
|
1.19 ± 2.01
|
0.86 ± 1.97 *
|
.038
|
Data are expressed as the mean ± standard deviation.
*, statistical difference relative to the lesser distraction force (P < .05).
P < .05 in boldface indicates a significant between-group difference.
Table 3 Between-group comparisons of post-operative outcomes at the last follow-up
|
Natural perception
|
Artificial perception
|
P Value
|
Knee extension angle, degrees
|
-5.2 ± 3.2
|
-6.8 ± 3.8
|
.583
|
Knee flexion angle, degrees
|
125.8 ± 8.8
|
124.3 ± 7.1
|
.782
|
Knee score, points
|
87.0 ± 11.8
|
86.1 ± 10.3
|
.764
|
Functional score, points
|
79.1 ± 17.6
|
65.4 ± 13.1
|
.021
|
VAS-knee pain, mm
|
15.3 ± 17.2
|
16.7 ± 9.6
|
.684
|
VAS-satisfaction, mm
|
25.1 ± 9.3
|
35.6 ± 11.2
|
.017
|
KOOS-JR, points
|
77.8 ± 7.8
|
70.1 ± 8.5
|
.032
|
Stiffness
|
After first wakening in the morning
|
0.9 ± 0.8
|
1.6 ± 1.0
|
.026
|
Pain
|
Twisting/pivoting on your knee
|
0.2 ± 0.7
|
0.3 ± 0.8
|
.524
|
|
Straightening knee fully
|
0.4 ± 0.7
|
0.6 ± 0.6
|
.312
|
|
Going up or down stairs
|
1.0 ± 0.6
|
1.0 ± 0.7
|
.813
|
|
Standing upright
|
0.4 ± 0.7
|
0.6 ± 0.8
|
.473
|
Function, daily living
|
Rising from sitting
|
0.7 ± 0.9
|
1.8 ± 1.1
|
<.001
|
|
Bending to floor/pick up an object
|
0.9 ± 0.8
|
1.6 ± 0.7
|
.013
|
EQ-5D-5L, points
|
0.72 ± 0.13
|
0.59 ± 0.11
|
.029
|
Hip knee ankle angle, degrees
|
0.4 ± 1.1
|
0.7 ± 0.9
|
.748
|
Femoral component medial angle, degrees
|
96.7 ± 1.2
|
97.3 ± 1.1
|
.826
|
Femoral component flexion angle, degrees
|
4.3 ± 1.3
|
5.6 ± 1.8
|
.091
|
Tibial component medial angle, degrees
|
89.3 ± 1.2
|
88.8 ± 1.3
|
.126
|
Posterior tibia slope, degrees
|
83.7 ± 2.1
|
85.1 ± 1.9
|
.637
|
Data are expressed as mean ± standard deviation or a count (%), as appropriate for the data type.
P < .05 in boldface indicates a significant between-group difference.
EQ-5D-5L, EuroQol 5-Dimension 5-Level scale; KOOS-JR, Knee Injury and Osteoarthritis Outcome Score for Joint Replacement; VAS, visual analog scale.
a Composite measure of pain and function, scored on a scale ranging from 0 to 100, with a higher value representing improved function and decreased pain.
b Pain after total knee arthroplasty was evaluated using a 100-mm VAS, with anchors at “0” mm (best) and “100” mm (worst). Satisfaction with the total knee arthroplasty was evaluated using a 100-mm VAS from “0” mm (complete satisfaction) to “100” mm (complete dissatisfaction).
Table 4 Predictive risk factors for an artificial knee joint perception post-TKA
|
Univariate analysis
|
Multivariate analysis
|
|
P Value
|
Odds ratio
|
95% CI
|
P Value
|
Age
|
.354
|
|
|
|
Male
|
.569
|
|
|
|
Gap difference at 20 lbf, mm
|
|
|
|
|
|
≥1.0
|
Reference
|
|
|
|
|
<1.0
|
.012 a
|
1.63
|
1.33 – 4.54
|
< .001 b
|
Statistically significant P-values are in boldface.
CI, confidence interval; TKA, total knee arthroplasty
a P < .2, statistically significant.
b P < .05, statistically significant.
Table 5 Comparison of demographic and outcome variables for a gap difference ≥1.0 mm or <1.0 mm
|
Gap difference at 20 lbf, mm
|
|
≥1.0
n = 27
|
<1.0
n = 33
|
P Value
|
Age, years
|
74.5 ± 7.2
|
73.8 ± 7.3
|
.756
|
Male, n (%)
|
4 (14.8)
|
6 (18.2)
|
.728
|
Body mass index, kg/m2
|
24.5 ± 3.2
|
25.2 ± 3.4
|
.662
|
Knee extension angle, degrees
|
-5.6 ± 3.1
|
-6.5 ± 3.5
|
.348
|
Knee flexion angle, degrees
|
125.3 ± 7.4
|
124.7 ± 6.4
|
.656
|
Patient’s joint perception, n (%)
|
|
|
.006
|
Natural perception
|
18 (66.7)
|
8 (24.2)
|
|
Artificial joint with no restriction
|
3 (11.1)
|
9 (27.3)
|
|
Artificial joint with minimal restriction
|
5 (18.5)
|
8 (24.2)
|
|
Artificial joint with major restriction
|
1 (3.7)
|
8 (24.2)
|
|
Non-functional joint
|
0 (0.0)
|
0 (0.0)
|
|
VAS-knee pain a, mm
|
14.8 ± 5.6
|
17.2 ± 5.7
|
.015
|
VAS-satisfaction a, mm
|
13.2 ± 7.4
|
45.7 ± 8.6
|
< .001
|
KOOS-JR, points
|
83.8 ± 6.4
|
65.0 ± 7.2
|
< .001
|
EQ-5D-5L, points
|
0.81 ± 0.08
|
0.52 ± 0.11
|
.032
|
Data are expressed as mean ± standard deviation or as a count (%), as appropriate for the data type.
P < .05 in boldface indicates a significant between-group difference.
EQ-5D-5L, EuroQol 5-Dimension 5-Level scale; KOOS-JR, Knee Injury and Osteoarthritis Outcome Score for Joint Replacement; VAS, Visual Analog Scale.
a Pain after total knee arthroplasty was evaluated using a 100-mm VAS, with anchors at “0” mm (best) and “100” mm (worst). Satisfaction with the total knee arthroplasty was evaluated using a 100-mm VAS from “0” mm (complete satisfaction) to “100” mm (complete dissatisfaction).