Table I.
Demographics and procedure characteristics. High-usage centres are defined as centres where ≥ 20% of annually performed knee arthroplasties in the surgical centre are medial unicompartmental knee arthroplasty (mUKA), and low-usage centres as centres where < 20% of annually performed knee arthroplasties in the surgical centre are mUKA.
| Variable | Overall | High-usage | Low-usage |
|---|---|---|---|
| Total, n | 3,757 | 2,377 | 1,380 |
| Mean age, yrs (SD) | 66.2 (9.2) | 66.2 (9.2) | 66.2 (9.4) |
| Mean BMI, kg/m2 (SD) | 28.8 (4.7) | 28.9 (4.6) | 28.8 (4.8) |
| Median length of stay, days (IQR) | 1 (0 to 1) | 1 (0 to 1) | 1 (1 to 2) |
| Male n (%) | 1,762 (46.9) | 1,138 (47.9) | 624 (45.2) |
| Year of surgery, n (%) | |||
| 2010 to 2012 | 497 (13.2) | 389 (16.4) | 108 (7.8) |
| 2013 to 2015 | 1,502 (40.0) | 1,005 (42.3) | 497 (36.0) |
| 2016 to 2018 | 1,758 (46.8) | 983 (41.4) | 775 (56.2) |
| Anaemia n (%) | 566 (15.9) | 319 (14.5) | 247 (18.1) |
| Use of walking aid, n (%) | |||
| No | 3,311 (88.1) | 2,108 (88.7) | 1,203 (87.2) |
| Yes | 380 (10.1) | 216 (9.1) | 164 (11.9) |
| Missing | 66 (1.8) | 53 (2.2) | 13 (0.9) |
| Hypertension n (%) | 1,976 (52.6) | 1,303 (54.8) | 673 (48.8) |
| Diabetes type, n (%) | |||
| No DM/diet | 3,421 (91.1) | 2,163 (91.0) | 1,258 (91.2) |
| Insulin-dependent DM | 68 (1.8) | 41 (1.7) | 27 (2.0) |
| Non-insulin-dependent DM | 268 (7.1) | 173 (7.3) | 95 (6.9) |
| Living situation, n (%) | |||
| With others | 2,818 (75.0) | 1,824 (76.7) | 994 (72.0) |
| Alone | 899 (23.9) | 533 (22.4) | 366 (26.5) |
| Institution | 6 (0.2) | 4 (0.2) | 2 (0.1) |
| Missing | 34 (0.9) | 16 (0.7) | 18 (1.3) |
| Cardiac disease, n (%) | |||
| No | 3,269 (87.0) | 2,039 (85.8) | 1,230 (89.1) |
| Yes | 480 (12.8) | 335 (14.1) | 145 (10.5) |
| Missing | 8 (0.2) | 3 (0.1) | 5 (0.3) |
| Pulmonary disease, n (%) | |||
| No | 3,399 (90.5) | 2,157 (90.7) | 1,242 (90.0) |
| Yes | 353 (9.4) | 218 (9.2) | 135 (9.8) |
| Missing | 5 (0.1) | 2 (0.1) | 3 (0.2) |
| Psychiatric disease, n (%) | 549 (14.6) | 335 (14.9) | 194 (14.1) |
| Potent antichoagulants, n (%) | 164 (4.4) | 110 (4.6) | 54 (3.9) |
| Cemented prosthesis, n (%) | 2,174 (57.9) | 1,377 (57.9) | 797 (57.8) |
*
Vitamin K-antagonists or novel oral anticoagulants.
DM, diabetes mellitus; IQR, interquartile range; SD, standard deviation.