The aim of the stepped-wedge cluster randomised trial is to investigate the effectiveness of using a clinical support tool (The MAP-Knee Tool) in managing adolescents aged 10-19 years with non-traumatic knee pain compared to not using the tool. Six participating hospitals will start to use the tool within 4, 6, or 8 months after recruitment start in a randomised order. We will investigate if using the tool is superior in terms of reducing symptoms compared to not using the tool.

The trial will be designed as a stepped-wedge cluster randomised superiority trial to be conducted across 6 hospital departments across Denmark. Any orthopaedic or similar hospital department in Denmark to which adolescents suffering from non-traumatic knee pain may be referred is eligible for participation. Any medical doctor or physiotherapist employed at either of the study sites who regularly see adolescents with non-traumatic knee pain will be eligible to participate in the trial.

Before crossover occurs at the study site, the adolescents will be treated as usual which is at the discretion of the treating clinician. Based on our current research on the usual care pathway, this will be heterogenous and include advice to wait and see, imaging (most often MRI and x-ray), or a rehabilitation plan for the municipality. After crossing over to using the MAP-Knee Tool, the treating clinician will use the MAP-Knee Tool together with the adolescent. The tool was designed to support the entire consultation from diagnosing the condition (patellofemoral pain, Osgood-Schlatter, Sinding-Larsson-Johansson, growth pain, patellar tendinopathy, or iliotibial band syndrome) to deciding on future management. The MAP-Knee Tool includes four separate components: 1) a tool for diagnosing the most common types of non-traumatic knee pain (SMILE), 2) credible explanations of the aetiology and pathogenesis specific to the diagnosis based on multiple methods with an iterative design, 3) a presentation of prognostic factors based on an individual participant data meta-analysis, and 4) an option grid that presents the users of the tool with pros and cons of commonly used management options based on a systematic literature search of systematic and narrative reviews within non-traumatic adolescent knee pain. An overarching focus of all components was to support shared decision-making and base decisions on all three pillars of evidence-based medicine: patient values, clinical expertise, and relevant research. Therefore, the tool should not provide the users with definitive answers simply based on available evidence. After the initial prototype of the tool including all four components had been made, the investigators performed end-user testing using think-aloud sessions with adolescents suffering from non-traumatic knee pain, adolescents with no history of knee pain, and medical doctors.

Inclusion Criteria:

• Having been referred to a hospital due to non-traumatic knee pain
• Age between 10 and 19 years

Exclusion Criteria:

• Knee pain with a traumatic origin
• Lack of ability to cooperate

De-identified data will be made available upon reasonable request.