Introduction Patient decision aids can support patient-clinician shared decision-making, yet little is known about the underlying change-mechanisms which facilitates patient-clinician collaboration in clinical settings. The MAP-Knee Tool was developed with GPs and adolescents with non-traumatic knee pain. It incorporated different components (diagnosis tool, credible explanations, prognostic factors, and an option grid) to support the consultation process and enhance patient-clinician collaboration. Our study was a Realist Evaluation of the effectiveness of the MAP-Knee Tool tested in a stepped-wedge randomised cluster trial in hospital settings.

Methods and Materials The Realist Evaluation investigates how, why, for whom and under which circumstances adolescents with knee pain and clinicians (GPs, physiotherapists, surgeons) benefitted from the MAP-Knee Tool though a theory-gleaning process. Data comprised intervention documents, survey data and qualitative realist interviews with researchers, adolescents, and clinicians. Thematic Realist Analysis of the qualitative data was applied, and findings were integrated with quantitative findings to establish an initial program theory and identify context-mechanism-outcome configurations.

Results Data indicated that absence of observable symptoms in adolescents increased the complexity of treatment situations, heightened diagnostic uncertainty, and complicated shared decision-making. However, clinicians employed various strategies to mitigate this complexity. Five context-mechanism-outcome configurations were identified, relating to clinicians’ confidence, recognizing patients pain experience, diagnostic uncertainty, credible explanations, defensive actions, and systemic barriers.

Conclusion Theory-gleaning indicated that the MAP-Knee tool likely facilitates shared decision-making by reducing the complexity within the treatment situation. However, additional data is needed to refine and expand the identified change-mechanisms, providing a more comprehensive understanding of their impact.