Background Knee pain affects one in three adolescents, which makes it one of the most common pain sites. Guideline recommendations about the clinical selection of patients likely to benefit from interventions are unclear, which leads to treatment heterogeneity and the potential of wasted resources among adolescents with a good prognosis. In contrast, adolescents with a poorer prognosis may not receive sufficient care. A newly developed clinical decision-support tool (The MAP-Knee Tool) intends to support clinicians in engaging with patients and adjusting the clinicians' evidence-based practices to accommodate patient preferences and treatment needs via a shared decision-making process. The aims of this trial are 1) to investigate the effectiveness of using a clinical decision-support tool (The MAP-Knee Tool) compared with usual care in adolescents with non-traumatic knee pain in reducing pain measured by KOOS-Child Pain after 12 weeks and 2) to investigate how the intervention worked, for whom, why and under which circumstances applying realist evaluation methodology. Methods This trial is a cluster-randomised superiority trial with a delayed intervention and a realist evaluation. Six hospital departments start with a usual care period of 4 months before randomly crossing over to using the intervention (The MAP-Knee Tool) after 4, 6, or 8 months, respectively. We will recruit 290 adolescents suffering from non-traumatic knee pain diagnoses who are followed for one year, with the change in KOOS-Child Pain after 12 weeks considered the primary endpoint. Secondary outcomes include 1) Global Rating of Change, 2) EQ-5D-Youth, 3) Anterior Knee Pain Youth, 4) the International Physical Activity Questionnaire short version, and 5) sports participation. The realist evaluation will utilise a prospective, qualitative approach for collecting data needed to develop and test a program theory and identify context-mechanism-outcome configurations essential for understanding how outcomes are achieved within specific contexts. Discussion This trial focuses on how the initial clinical encounter can be improved to meet the support and management needs of adolescents with chronic knee pain seeking treatment for knee pain in secondary care and investigates how the intervention worked, for whom, why and under which circumstances. Trial registration Clinicaltrials.gov (NCT05791513). Prospectively registered on March 30th, 2023.

The authors have declared no competing interest.

NCT05791513

This study was funded by TrygFonden and The Independent Research Fund Denmark

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The trial was approved by the Ethics Committee of the North Denmark Region (N-20220043).

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All data produced in the present study are available upon reasonable request to the authors