Patient characteristics

By type of knee prosthesis
By diagnosis
Age category
Previous surgery

Knee » Patient characteristics » By type of knee prosthesis

TABLE Patient characteristics of all patients with a registered primary knee arthroplasty by type of knee arthroplasty in the Netherlands in 2020

	TKA	UKA	PFA	Total¹
N	(n=19,501)	(n=4,677)	(n=158)	(n=24,359)
Mean age (years) (SD)	68.9 (8.8)	64.7 (8.7)	55.8 (9.9)	68.0 (9.0)
Age (years) (%)
<50	1	3	25	2
50-59	14	25	41	16
60-69	34	41	25	36
70-79	40	27	9	37
≥80	11	4	0	9
Gender (%)
Men	38	47	25	39
Women	62	53	75	61
ASA score (%)
I	12	19	32	13
II	64	67	58	65
III-IV	24	14	9	22
Type of hospital (%)
General	80	71	81	78
UMC	1	0	3	1
Private	19	29	16	21
Diagnosis (%)
Osteoarthritis	97	98	97	97
Post-traumatic	2	0	2	1
Rheumatoid arthritis	1	0	0	1
Osteonecrosis	0	1	0	1
Other	0	0	1	0
Charnley-score (%)
A One knee joint affected	37	49	45	39
B1 Both knee joints affected	35	32	34	35
B2 Contralateral knee joint with a total knee prosthesis	24	17	18	23
C Multiple joints affected or chronic disease that affects quality of life	4	2	3	3
Mean Body Mass Index (kg/m²) (SD)	29.5 (5.0)	28.9 (4.3)	27.7 (3.9)	29.4 (4.9)
Body Mass Index (kg/m²) (%)
Underweight (≤18,5)	0	0	0	0
Normal weight (>18,5-25)	18	19	24	18
Overweight (>25-30)	41	45	50	42
Obesity (>30-40)	38	35	25	37
Morbid obesity (>40)	3	1	1	3
Smoking (%)
No	93	91	91	93
Yes	7	9	9	7

¹ Also contains 15 (0.06%) primary knee arthroplasties that were registered as other and 8 (0.03%) primary knee arthroplasties of which the type of prosthesis had not been registered.
TKA: total knee arthroplasty; UKA: unicondylar knee arthropalsty; PFA: patellofemoral knee arthroplasty; General: general hospital; UMC: university medical centre; Private: private hospital; SD: standard deviation.

Knee » Patient characteristics » By diagnosis

TABLE Patient characteristics of all patients with a registered primary knee arthroplasty by type of diagnosis in the Netherlands in 2020

	Osteoarthritis	Post-traumatic	Rheumatoid arthritis	Osteonecrosis	Total
N	(n=23,450)	(n=337)	(n=234)	(n=142)	(n=24,359)
Mean age (years) (SD)	68.1 (8.9)	62.2 (10.6)	65.0 (9.2)	69.6 (10.6)	68.0 (9.0)
Age (years) (%)
<50	2	11	4	2	2
50-59	16	29	22	10	16
60-69	36	34	41	35	36
70-79	37	22	28	35	37
≥80	10	4	5	18	9
Gender (%)
Men	40	39	24	39	39
Women	60	61	76	61	61
ASA score (%)
I	13	19	1	9	13
II	65	64	65	69	65
III-IV	22	17	34	22	22
Type of hospital (%)
General	78	71	91	79	78
UMC	1	9	4	4	1
Private	21	20	5	17	21
Charnley-score (%)
A One knee joint affected	39	76	24	76	39
B1 Both knee joints affected	35	14	35	11	35
B2 Contralateral knee joint with a total knee prosthesis	23	6	17	7	23
C Multiple joints affected or chronic disease that affects quality of life	3	4	24	6	3
Mean Body Mass Index (kg/m²) (SD)	29.4 (4.8)	28.6 (5.1)	29.1 (5.7)	28.9 (4.5)	29.4 (4.9)
Body Mass Index (kg/m²) (%)
Underweight (≤18,5)	0	2	1	0	0
Normal weight (>18,5-25)	18	23	24	19	18
Overweight (>25-30)	42	40	37	44	42
Obesity (>30-40)	37	32	34	35	37
Morbid obesity (>40)	3	3	4	2	3
Smoking (%)
No	93	86	88	90	93
Yes	7	14	12	10	7

Please note: In 2020, 115 (0.5%) patients had a primary knee arthroplasty after a diagnosis that is not listed in the table. Of 81 (0.3%) primary knee arthroplasties the diagnosis was not registered.
General: general hospital; UMC: university medical centre; Private: private hospital; SD: standard deviation.

Knee » Patient characteristics » Age category

FIGURE Trend (proportion [%] per year) in age category in primary total knee arthroplasties in the Netherlands in 2010-2020

Year

Age category (%)

<50

2.62

2.89

2.79

2.64

2.38

2.41

2.01

2.19

1.76

1.50

1.38

2.21

50-59

14.92

14.82

15.58

15.06

14.75

14.88

14.39

14.37

13.99

13.15

13.97

14.50

60-69

34.50

34.60

35.86

36.68

37.10

36.06

36.52

35.07

34.15

34.20

34.24

35.39

70-79

34.33

34.53

33.65

33.99

34.13

35.07

35.86

36.72

38.33

39.69

39.59

36.07

>80

13.63

13.15

12.13

11.63

11.64

11.58

11.23

11.65

11.77

11.46

10.81

11.83

Total (n):

251,989

18,483

19,483

21,675

22,266

24,216

24,237

24,864

25,551

25,837

25,877

19,500

TKA: total knee arthroplasty.

Knee » Patient characteristics » Previous surgery

TABLE Trend (proportion [%] per year) in previous surgeries to the same joint in patients who underwent a primary knee arthoplasty in the Netherlands in 2014-2020

Year	2014	2015	2016	2017	2018	2019	2020	Total
Primary knee arthroplasty (n)	26,035	26,479	27,805	29,297	28,216	28,007	24,205	190,089
Previous surgery to the relevant knee (total) Proportion¹ (%)	35.7	34.5	33.4	28.0	25.2	24.6	23.1	29.2
Meniscectomy	28.4	27.3	26.6	22.1	20.6	19.9	18.4	23.3
Arthroscopy	17.7	18.9	19.3	17.1	15.6	15.3	14.3	16.9
Osteotomy	3.0	3.0	2.8	2.9	2.8	2.4	2.3	2.7
Osteosynthesis	1.7	1.7	1.4	1.5	1.5	1.6	1.4	1.5
ACL reconstruction	1.3	1.5	1.5	1.5	1.4	1.5	1.8	1.5
Synovectomy	1.2	1.2	1.0	0.8	0.6	0.6	0.7	0.9
Patella realignment	0.7	0.6	0.5	0.6	0.6	0.5	0.5	0.6
Other	2.6	2.3	2.6	2.4	2.4	2.8	2.6	2.5

¹ A patient may have undergone multiple previous surgeries to the same joint. As such, the total proportion is more than the total proportion of patiens with one or more previous surgeries to the same joint.

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