A total of 181 subjects were selected to participate in this study; the mean age was 67.3 ± 6.8 years, 56.35% were female, and 43.64% were male. The radiological severity are described in Table 1. A total of 53.57% of the females were included in the grades 0 and 1 group, and 60.86% were included in the grades 2 to 4 group.
Table 1. Description of the sample by radiological severity (K&L).
Radiological Grade
|
0
|
1
|
2
|
3
|
4
|
Number of elderly
|
60
|
52
|
24
|
32
|
13
|
Frequency (%)
|
33.15
|
28.73
|
13.26
|
17.68
|
7.18
|
When the K&L scale grades were divided into two groups, classified by the presence (grades 2 to 4) or absence (grades 0 and 1) of knee osteoarthritis (KOA), 69 and 112 subjects were included in the grades 2 to 4 and grades 0 and 1 groups, accounting for 38.12% and 61.88% of the study population, respectively. Most of the population evaluated in this study had radiological grades that were not indicative of the presence of KOA. A minority of the population were diagnosed with the disease, with a predominance of grade 3 (moderate).
The average scores for the GDS, MMSE and WOMAC tests indicated that the population was generally had a “mild” level of depressive symptoms and cognitive loss and a “low” level of pain, stiffness and functional difficulty. The average scores in the TUG and BBS tests indicated that the elderly people had a low risk of falling (Table 2).
3.1 Relationship between the scores of the instruments evaluated and the radiological grades of the Kellgren-Lawrence scale.
When each of the grades of the K&L scale, including 0, 1, 2, 3 and 4, were compared to the GDS, MMSE, WOMAC, TUG and BBS scores, no significant differences were observed in any of the categorical variables (Table 2). The same result was observed in the comparative analysis in relation to the continuous variables (Table 3).
Table 2. Comparison between grades of the Kellgren-Lawrence between categorical variables and description of the sample regarding the performance in the evaluated tests.
|
Grade 0
|
Grade 1
|
Grade 2
|
Grade 3
|
Grade 4
|
|
|
Variable
|
N (%)
|
N (%)
|
N (%)
|
N (%)
|
N (%)
|
p-Value*
|
Mean (SD)
|
GDS
|
|
|
|
|
|
p=0.988
|
6.89 (1.68)
|
0 - 5
|
9 (16.36)
|
5 (12.50)
|
6 (18.75)
|
8 (20.00)
|
2 (15.38)
|
|
|
6 – 10
|
43 (78.18)
|
35 (85.00)
|
25 (78.13)
|
30 (75.00)
|
11 (84.62)
|
|
|
11 - 15
|
3 (5.45)
|
1 (2.50)
|
1 (3.13)
|
2 (5.00)
|
0 (0.00)
|
|
|
MMSE
|
|
|
|
|
|
p=0.774
|
23.45 (3.98)
|
0 - 9
|
1 (1.82)
|
0 (0.00)
|
0 (0.00)
|
0 (0.00)
|
0 (0.00)
|
|
|
10 - 20
|
9 (16.36)
|
8 (20.00)
|
7 (21.88)
|
12 (30.00)
|
3 (23.08)
|
|
|
21 - 26
|
28 (50.51)
|
22 (55.00)
|
13 (46.88)
|
22 (33.00)
|
6 (46.15)
|
|
|
>=27
|
17 (30.91)
|
10 (25.00)
|
10 (31.23)
|
6 (15.00)
|
4 (30.77)
|
|
|
WOMAC
|
|
|
|
|
|
p=0.450
|
16.25 (21.4)
|
0 - 25
|
19 (31.67)
|
18 (34.62)
|
8 (33.33)
|
5 (15.63)
|
2 (15.38)
|
|
|
26 - 50
|
29 (48.33)
|
24 (46.15)
|
12 (50.00)
|
18 (56.23)
|
4 (30.77)
|
|
|
51 - 75
|
8 (13.33)
|
6 (11.54)
|
2 (8.33)
|
5 (15.63)
|
4 (30.77)
|
|
|
76 - 100
|
4 (6.67)
|
4 (7.69)
|
2 (8.33)
|
4 (12.50)
|
3 (23.08)
|
|
|
TUG
|
|
|
|
|
|
p=0.124
|
10.88 (4.74)
|
0 – 10
|
32 (53.33)
|
28 (53.85)
|
15 (62.50)
|
19 (59.30)
|
5 (38.46)
|
|
|
11 – 20
|
27 (45.00)
|
24 (46.15)
|
9 (37.50)
|
11 (34.38)
|
6 (46.15)
|
|
|
21 – 29
|
1 (1.67)
|
0 (0.00)
|
0 (0.00)
|
0 (0.00)
|
2 (15.38)
|
|
|
>=30
|
0 (0.00)
|
0 (0.00)
|
0 (0.00)
|
2 (6.25)
|
0 (0.00)
|
|
|
BBS
|
|
|
|
|
|
p=0.061
|
50.28 (6.65)
|
0 – 36
|
3 (5.000
|
1 (1.92)
|
2 (8.33)
|
2 (6.25)
|
3 (23.08)
|
|
|
37 - 44
|
1 (1.67)
|
2 (3.85)
|
1 (4.17)
|
4 (12.50)
|
1 (7.69)
|
|
|
45 - 56
|
56 (93.33)
|
49 (94.23)
|
21 (87.50)
|
26 (81.25)
|
9 (69.23)
|
|
|
* p-Value for the Fisher's exact test.
Table 3. Comparison between grades of the Kellgren-Lawrence between continuos variables.
|
Grade 0
|
Grade 1
|
Grade 2
|
Grade 3
|
Grade 4
|
|
Variable
|
Mean (SD)
|
Mean (SD)
|
Mean (SD)
|
Mean (SD)
|
Mean (SD)
|
p- Value*
|
|
|
|
|
|
|
|
GDS
|
6.98 (1.84)
|
6.95 (1.50)
|
6.47 (1.61)
|
7.08 (1.76)
|
6.77 (1.48)
|
p=0.314
|
MEEM
|
23.87 (4.06)
|
23.63 (3.56)
|
24.13 (4.32)
|
22.43 (3.63)
|
22.62 (4.87)
|
p=0.205
|
WOMAC
|
13.60 (19.07)
|
13.23 (18.58)
|
15.08 (19.70)
|
19.69 (24.17)
|
34.23 (30.06)
|
p=0.064
|
TUG
|
10.28 (3.31)
|
10.21 (2.27)
|
10.32 (2.46)
|
12.16 (8.53)
|
14.19 (6.38)
|
p=0.265
|
BBS
|
50.92 (5.86)
|
51.37 (6.12)
|
50.54 (6.23)
|
48.66 (7.29)
|
46.46 (9.70)
|
p=0.179
|
* p-Value for the Kruskal-Wallis test.
The results suggest that when the radiological grades are independently evaluated, the K&L scale is not statistically related to any of the tests evaluated.
3.2 Relationship between the scores of the instruments evaluated and the radiological grades of the Kellgren-Lawrence scale divided into two groups.
When the grades of the K&L scale classified into two groups, “0 and 1” and “2 to 4”, were compared with the categorical variables, the BBS score significantly differed by the K&L grade, with a higher frequency of high and moderate grades, from 2 to 4, with higher BBS scores (p=0.031, Additional file 1). This result suggests that elderly people with KOA more commonly have a moderate or high risk of falling. For the other instruments evaluated, no significant differences were found (Additional file 1).
The comparison between groups and continuous variables showed a significant difference in the WOMAC and BBS scores (Table 4). These results indicate that the levels of pain, stiffness, functional difficulty and risk of falling are higher in elderly people with KOA than in elderly people without KOA.
Table 4. Comparative analysis between groups and continuous variables.
|
Group 0 and 1 (N=112)
|
Group 2 to 4 (N=69)
|
|
Variable
|
Mean (SD)
|
Mean (SD)
|
p-Value*
|
GDS
|
6.97 (1.70)
|
6.80 (1.67)
|
p=0.298
|
MMSE
|
23.77 (3.84)
|
23.09 (4.13)
|
p=0.295
|
WOMAC
|
13.43 (18.76)
|
20.83 (24.57)
|
p=0.026
|
TUG
|
10.25 (2.86)
|
11.90 (6.65)
|
p=0.408
|
BBS
|
51.13 (5.96)
|
48.90 (7.49)
|
p=0.035
|
|
|
|
|
|
*p-Value for the Mann-Whitney test.
3.3 Correlation between continuous variables and the grades of the Kellgren-Lawrence scale.
In the correlation analysis between the continuous variables and grades of KOA (in the total study population and subgroups), a significant correlation was found for the WOMAC score (Table 5).
Table 5. Analysis of correlation between continuous variables and the grades of the Kellgren-Lawrence.
|
Total Sample (N=181)
|
Group 0 and 1 (N=112)
|
Group 2 to 4 (N=69)
|
Variable
|
r
|
p
|
r
|
p
|
r
|
p
|
GDS
|
-0.03544
|
0.6367
|
-0.01559
|
0.8808
|
0.16215
|
0.1382
|
MEEM
|
-0.01185
|
0.8746
|
-0.07265
|
0.4841
|
0.05039
|
0.6470
|
WOMAC
|
0.17099
|
0.0214
|
-0.02285
|
0.8110
|
0.22709
|
0.0606
|
TUG
|
0.08274
|
0.2681
|
0.00831
|
0.9307
|
0.20181
|
0.0963
|
BBS
|
-0.14007
|
0.0600
|
0.04691
|
0.6234
|
-0.15289
|
0.2098
|
* r = Spearman's correlation coefficient; p = p-Value; N = number of subjects.
This result suggests that the higher the radiological grade of KOA, the higher the WOMAC score is.
3.4 Comparative and correlation analyses between the Kellgren-Lawrence grades and WOMAC domain scores.
Based on the results presented, significant differences between the WOMAC domains and the Kellgren-Lawrence scale were suspected, and the differences were investigated. The three WOMAC domains (pain, stiffness and functional limitations) were compared with the individual grades and groups of grades (0 and 1 and 2 to 4) (Additional files 2 and 3). In addition, a correlation analysis was performed between the WOMAC domain scores and the radiological scores in the total study population and in subgroups (Additional file 4). No significant differences were observed in any of the analyses.