Procedure description and patient characteristics
| Characteristic, n (%) | Denmark* | Luxembourg† | Norway‡ | Sweden§ | UK¶ | US** |
| Established/start date | July 2005 | March 2011 | June 2004 | January 2005 | March 2013 | February 2005 |
| Primary procedures | 21 820 | 300 | 17 556 | 30 422 | 2972 | 28 055 |
| Age (at time of surgery) (years) | ||||||
| <15 | 635 (2.9) | 10 (3.3) | 374 (2.1) | 788 (2.6) | 45 (1.5) | 948 (3.4) |
| 15–19 | 4635 (21.2) | 61 (20.3) | 4219 (24.0) | 7982 (26.2) | 452 (15.3) | 7506 (26.7) |
| 20–24 | 4271 (19.6) | 55 (18.3) | 3135 (17.9) | 6570 (21.6) | 602 (20.4) | 4178 (14.9) |
| 25–29 | 3195 (14.6) | 57 (19.0) | 2484 (14.1) | 4652 (15.3) | 612 (20.7) | 3673 (13.1) |
| 30–34 | 2721 (12.5) | 42 (14.0) | 2143 (12.2) | 3223 (10.6) | 379 (12.8) | 3310 (11.8) |
| 35–39 | 2522 (11.6) | 27 (9.0) | 2074 (11.8) | 2800 (9.2) | 281 (9.5) | 2851 (10.2) |
| ≥40 | 3841 (17.6) | 48 (16.0) | 3127 (17.8) | 4407 (14.5) | 586 (19.8) | 5589 (19.9) |
| Gender | ||||||
| Male | 13 244 (60.7) | 215 (71.7) | 9975 (56.8) | 17 548 (57.7) | 2153 (72.4) | 17 618 (62.8) |
| Female | 8576 (39.3) | 85 (28.3) | 7581 (43.2) | 12 874 (42.3) | 819 (27.6) | 10 437 (37.2) |
| BMI (kg/m2) | ||||||
| <25 | – | 176 (58.7) | 2983 (56.4) | 8452 (62.5) | 525 (51.0) | 10 890 (39.3) |
| 25–29 | – | 101 (33.7) | 1773 (33.5) | 4246 (31.4) | 377 (36.6) | 10 381 (37.4) |
| ≥30 | – | 23 (7.6) | 537 (10.1) | 834 (6.2) | 128 (12.4) | 6455 (23.3) |
| Prior procedure to the index knee | – | 22 (7.3) | 3427 (19.5) | – | – | 1193 (4.3) |
| No injury to the contralateral ACL | 19 682 (92.1) | 248 (82.7) | 13 958 (92.0) | 23 107 (91.7) | – | 12 876 (93.5) |
| Operative side | ||||||
| Right | 10 926 (50.9) | 166 (55.3) | 8941 (50.9) | 15 729 (51.7) | 1357 (51.0) | 13 793 (49.2) |
| Left | 10 525 (49.1) | 134 (44.7) | 8615 (49.1) | 14 684 (48.3) | 1303 (49.0) | 14 262 (50.8) |
| Time to reconstruction (months)†† | ||||||
| 0–3 | 4665 (22.3) | 107 (35.8) | 3383 (24.0) | 3825 (13.8) | 249 (40.9) | 7002 (43.8) |
| 4–6 | 4772 (22.8) | 74 (24.7) | 3120 (22.1) | 6347 (22.9) | 155 (25.5) | 3739 (23.4) |
| 7–12 | 4633 (22.1) | 52 (17.4) | 3263 (23.1) | 8060 (29.1) | 120 (19.7) | 2260 (14.1) |
| >12 | 6875 (32.8) | 66 (22.1) | 4346 (30.8) | 9428 (34.1) | 85 (14.0) | 2980 (18.6) |
| Follow-up time (years)‡‡, median (IQR) | 4.6 (2.3–6.8) | 0.4 (0.2–0.9) | 5.0 (2.6–7.6) | 4.4 (2.2–6.9) | 1 (–) | 2.8 (1.3–4.8) |
*Missing data: no contralateral injury: 439 (2.0); operative side: 369 (1.7%); time to reconstruction: 875 (4.0%).
†Missing data: time to reconstruction: 1 (0.3%).
‡Missing data: BMI: 12 263 (69.8%); no contralateral injury: 2391 (13.6); time to reconstruction: 3444 (19.6%).
§Missing data: BMI: 16 890 (55.5%); no contralateral injury: 5235 (17.2); operative side: 9 (0.0%); time to reconstruction: 2762 (9.1%).
¶Missing data: age: 15 (0.5%); BMI: 1942 (65.3%); operative side: 312 (10.5%); time to reconstruction: 2363 (79.5%).
**Missing data: BMI: 329 (1.2%); no contralateral injury: 14 285 (50.9%); time to reconstruction: 12 074 (43.0%).
††Calculated as the difference between the date of surgery and date of injury.
‡‡Calculated as the difference between the censoring date and the date for surgery. The censoring date is the last date of follow-up or the study end date (31 December 2014), whichever came first.
§§Loss to follow-up defined as death, emigration or membership termination (for KP) prior to the study end date.
–, not reported; ACL, anterior cruciate ligament; BMI, body mass index; KP, Kaiser Permanente.