KOOS thresholds corresponding to the three responder criteria MIC, PASS and TF at 6–24 months following ACL reconstruction in a random sample from the Norwegian knee ligament registry7 9
| KOOS subscale (0–100, worst to best) | MIC | PASS | TF |
| Pain | 2.5 | 89 | 57 |
| Symptoms | −1.2 | 83 | 56 |
| ADL | 2.4 | 95 | 71 |
| Sport/recreation | 12.1 | 72 | 28 |
| QOL | 18.3 | 73 | 28 |
| KOOS4* | 9 | 79 | 42 |
*KOOS4 thresholds were calculated from a previous cohort7 9 for the purpose of this study. KOOS4 scores correspond to the average score for four of the five KOOS subscales: pain, symptoms, sport/recreation and QOL.11 The KOOS QOL question given in table 1 was used as the anchor item.
ADL, activities of daily living; KOOS, Knee injury and Osteoarthritis Outcome Score; MIC, minimal important change; PASS, patient acceptable symptom state; QOL, quality of life; TF, treatment failure.