Table 1.
Study measures
| Construct assessed | Data collection instrument | Time of collection |
| Primary outcome measure | Patient-reported outcomes | |
| Pain | Pain subscale of the KOOS | 0, 3, 6, 12 and 24 months |
| Secondary outcome measures | Data collection instrument | Time of collection |
| Patient-reported outcomes | ||
| Symptoms, ADL, QOL, sport & recreation | Four individual subscales of the KOOS | 0, 3, 6, 12 and 24 months |
| Pain intensity, sites, & interference with functioning | Brief Pain Inventory | 0, 3, 6, 12 and 24 months |
| Health-related quality of life | EuroQol-5D-5L | 0, 3, 6, 12 and 24 months |
| Ability to forget about the knee | Forgotten Joint Score | 0, 3, 6, 12 and 24 months |
| Pain catastrophizing | Pain Catastrophizing Scale | 0, 3, 6, 12 and 24 months |
| Anchor measures of satisfaction | Patient acceptable symptom state | 0, 3, 6, 12 and 24 months |
| Treatment failure | 3, 6, 12 and 24 months | |
| Global perceived effect | 3, 6, 12 and 24 months | |
| Objective measures | ||
| Functional lower extremity test | 30-s sit-to-stand test | 0, 3, 6, 12 and 24 months |
| Adverse events | Treatment records, hospital records, questionnaire | Continuously – 12 monts |
| Other measures | Time of collection | |
| Patient-reported outcomes | ||
| Sleep quality | Pittsburgh Sleep Quality Index | 0, 3, 6, 12 and 24 months |
| Mood states | Hospital Anxiety and Depression Scale | 0, 3, 6, 12 and 24 months |
| Pain-related fear of movement | Fear-Avoidance Belief Questionnaire | 0, 3, 6, 12 and 24 months |
| Health locus of control | Health Locus of Control Scale | 0, 3, 12 and 24 months |
| Self-reported level of physical activity level and readiness for change | HUNT2, Stages of Change physical activity | 0, 3, 6, 12 and 24 months |
| Digital health literacy | The eHealth Literacy Questionnaire | 0 and 6 months |
| Health literacy | The International Health Literacy Population survey Questionnaire 2019–2021 | 0 and 6 months |
| Comorbidity | Self-Administered Comorbidity Questionnaire | 0 months |
| Objective measures | ||
| Time in active position/number of steps | ActiGraph Professional Single Axis accelerometer | 0, 6, 12 and 24 months |
| Physical function -walking | 40-m fast paced walk test | 0, 3, 6, 12 and 24 months |
| Lower body strength and balance | Stair climb test | 0, 3, 6, 12 and 24 months |
| Body mass index | Weight from baseline to follow-up | 0, 3, 6, 12 and 24 months |
| Radiological assessments | Weightbearing AP, lateral view, Rosenberg view and long leg weightbearing AP view (HKA) | 0 and 12 months |
| Registry-based data | ||
| Use of health care resources | KUHR-system | 0 to 24 months |
| Norwegian Patient Registry | 0 to 24 months | |
| FD trygd social security data base | 0 to 24 months | |
| Norwegian Prescription Database | 0 to 24 months | |
| The Norwegian Arthroplasty registry | 0 to 24 months | |
Abbreviations: ADL Activities of daily living, KOOS Knee injury and Osteoarthritis Outcome Score