Correlation between Kellgren-Lawrence classification of osteoarthritis and Knee Injury and Osteoarthritis Outcome Score

Table 1 Sociodemographic details

Sociodemographic details		Number	%
Age	< 18	4	2.4
	19-29	8	4.9
	30-39	12	7.3
	40-49	29	17.7
	50-59	49	29.9
	≥ 60	62	37.8
Gender	Female	102	62.2
	Male	62	37.8
Body mass index	Underweight	2	1.2
	Normal	18	11.0
	Overweight	42	25.6
	Obese	102	62.2
Grading on X-rays for osteoarthritis	1	9	5.5
	2	43	26.2
	3	55	33.5
	4	57	34.8

Data are presented as number (n) and percentage (%). Grading on X-rays is based on Kellgren-Lawrence classification for osteoarthritis.

Table 2 Comparison of age of patients with different domains of Knee Injury and Osteoarthritis Outcome Score

Domain scale (0-100)	Age	Number	Mean	SD	P value
Pain	< 18	4	75.69	7.98	< 0.001
	19-29	8	68.06	23.00
	30-39	12	53.94	26.34
	40-49	29	51.72	21.38
	50-59	49	49.60	23.06
	≥ 60	62	38.40	21.83
Symptoms	< 18	4	70.54	6.10	0.573
	19-29	8	64.73	7.50
	30-39	12	59.23	6.18
	40-49	29	58.00	17.57
	50-59	49	57.87	15.36
	≥ 60	62	57.20	18.66
Activities of daily living	< 18	4	86.40	10.36	< 0.001
	19-29	8	79.41	18.20
	30-39	12	67.65	25.81
	40-49	29	60.95	20.49
	50-59	49	55.25	24.08
	≥ 60	62	46.54	22.09
Sport and recreation function	< 18	4	70.00	20.00	< 0.001
	19-29	8	68.75	30.68
	30-39	12	55.00	30.90
	40-49	29	43.10	30.37
	50-59	49	38.27	31.55
	≥ 60	62	30.32	26.96
Knee-related quality of life	< 18	4	56.25	13.50	< 0.001
	19-29	8	66.41	30.42
	30-39	12	52.60	25.76
	40-49	29	46.34	23.24
	50-59	49	44.01	19.97
	≥ 60	62	34.38	18.55

The age wise comparison of five outcome scale is shown in Table 2. Scores range from 0 (worst) to 100 (best). Statistical analysis was performed using one-way analysis of variance.

Table 3 Comparison of patients’ gender with different domains of Knee Injury and Osteoarthritis Outcome Score

Domain scale (0-100)	Gender	Number	Mean	SD	P value
Pain	Female	102	46.4869	23.77010	0.445
	Male	62	49.4176	23.76337
Symptoms	Female	102	56.1275	16.87450	0.022
	Male	62	62.0968	14.60926
Activities of daily living	Female	102	54.2532	23.47466	0.291
	Male	62	58.3729	25.28356
Sport and recreation function	Female	102	37.8922	31.57920	0.364
	Male	62	42.4194	29.70817
Knee-related quality of life	Female	102	41.1152	21.81855	0.216
	Male	62	45.5645	22.87000

Scores range from 0 (worst) to 100 (best). Independent sample t-test was used for comparison.

Table 4 Correlation of scores of five outcomes

		Symptoms	Activities of daily living	Sport and recreation function	Knee-related quality of life
Pain	Rho	0.363	0.871	0.688	0.754
	P value	< 0.001	< 0.001	< 0.001	< 0.001
Symptoms	Rho	-	0.396	0.298	0.474
	P value		< 0.001	< 0.001	< 0.001
Activities of daily living	Rho	-	-	0.752	0.755
	P value			< 0.001	< 0.001
Sport and recreation function	Rho	-	-	-	0.709
	P value				< 0.001

Correlations calculated using Pearson’s correlation coefficient. All P values are two-tailed and statistically significant at P < 0.001.

Table 5 Logistic regression to predict factors related to severe Knee Injury and Osteoarthritis Outcome Score (< 40)

	Predictor variable	Odds ratio	95%CI	P value
Age	19-29	1.38	0.45-4.20	0.769
	40-49	1.94	0.88-4.28	0.574
	50-59	2.43	1.15-5.12	< 0.001
	≥ 60	1.81	0.79-3.09	0.122
	≤ 18	Reference
Gender	Female	1.04	1.03-2.95	0.339
	Male	Reference
Body mass index	Underweight	2.16	0.29-15.91	0.455
	Overweight	1.36	0.65-2.87	0.415
	Obese	2.79	1.41-5.51	0.003
	Normal	Reference
Kellgren-Lawrence grading	Grade 2	2.11	0.85-5.27	0.107
	Grade 3	4.32	1.73-10.78	0.002
	Grade 4	7.88	3.10-20.04	< 0.001
	Grade 1	Reference