Table 3 Overview of outcome domains and prioritized hierarchy of outcomes

Primary outcome

Sport function

1. KOOS-child ‘Sport/play’ 0-100 subscale (7 items)

Secondary outcomes

Secondary outcomes

Patient-acceptable Symptom-state

2. PASS question (Y/N)

Knee-related Quality of Life

3. KOOS-child ‘Quality of Life’ 0-100 subscale (5 items)

Pain intensity and frequency (Pain flares)

4. 4-week-average episodes of pain flares (≥4 on 0-10 NPRS)

5. Worst pain past week (0-10 NPRS)

11. KOOS-child question P1 on ‘Pain’ subscale (1-5 Likert scale)

12. Level of pain/discomfort (EQ-D5-Y 4)

Participation in sports and physical activity

6. 4-week average hours of sports participation

13. 4-week average hours of MVPA

14. Satisfaction with extent of sports participation

15. Pre knee pain level of sports participation

16. Pre knee pain level of physical activity

17. Time to return to sport (week no.)

Osgood-Schlatter morphology (ultrasound imaging)

7. Flaviis composite severity score

18. Tendinosis signs (thickening or hyperemia)

19. Infrapatellar bursitis signs (effusion or hyperemia

20. Hyperemia of the tibial tubercle ad modum Öhberg

Pain during knee loading

8. Anterior Knee Pain Provocation test (0-10 NPRS)

21. Pain during knee extension test (0-10 NPRS)

22. Pressure-pain threshold at the tibial tubercle (kPa)

23. KOOS-child ‘Pain’ 0-100 subscale (8 items)

24. Known pain during manual palpation

25. Pain during countermovement jump (0-10 NPRS)

Objective knee function

26. Maximal isometric knee extension strength (Nm/kg)27. Countermovement jump height (cm)28. Countermovement power (W)29. Knee extensor flexibility change (°)

Global rating of change

9. 7-point Likert scale

30. Satisfaction with treatment (Y/N)

Usual activities

10. Patient-specific function scale (NRS 0-10)

31. Problems with usual activities (EQ-D5-Y 3)

Pain beliefs

32. Kinesiophobia (Tampa Scale of Kinesiophobia, 17 items)

Health

33. Self-rated health (EQ-D5-Y 0-100 VAS)

Safety outcomes

1. Any adverse events