Risk of bias assessment
| Newcastle-Ottawa scale domain | Evaluation of risk of bias in included studies | |||
| Not appropriate, n (%) | High risk, n (%) | Unclear, n (%) | Low risk, n (%) | |
| Selection | ||||
| Representativeness of exposed cohort | 63 (84) | 1 (1) | 11 (15) | |
| Representativeness of the controls | 69 (92) | 1 (1.3) | 5 (6.7) | |
| Demonstration that outcome of interest was not present at start of the study | 51 (68) | 5 (7) | 19 (25) | |
| Ascertainment of the exposure (ACL injury treatment) | 75 (100) | |||
| Comparability | ||||
| Comparability of cohorts | 73 (97) | 1 (1.3) | 1 (1.3) | |
| Outcome | ||||
| Assessment of outcome | 52 (69) | 21 (28) | 2 (3) | |
| Was follow-up long enough for outcomes to occur (minimum 2 years) | 15 (20) | 3 (4) | 57 (76) | |
| Adequacy of follow-up of cohorts (minimum 80%) | 25 (33) | 9 (12) | 41 (55) | |
ACL, anterior cruciate ligament.