Objective To use individual patient data (IPD) to investigate if the effect of pain on sports-related disability is mediated through physical (lower extremity isometric strength) or psychological (depression/anxiety and knee confidence) factors in adolescents with non-traumatic anterior knee pain.
Methods This study included four datasets from a previously harmonised IPD dataset. Prior to analysis, the protocol and analysis approach were predefined and published on Open Science Framework. Potential mediators were pre-sepcified as isometric knee and hip strengths, self-reported anxiety/depression and confidence in the knee, all
measured at 12 weeks after baseline evaluation. Mediation analyses were undertaken using the CMAVerse package in RStudio using the regression-based approach to decompose the total effect of the exposure (pain at baseline evaluation) on the outcome (sports-related disability at 6 months) into the ‘indirect effect’ (the portion of the total effect acting through the mediators) and the ‘direct effect’.
Results Two-hundred and seventy-nine adolescents with non-traumatic knee pain were included in the analysis. Median age was 13 (range 10–19), and 72% were women. Baseline pain was associated with sports-related disability at 6 months. There was no evidence of the association being mediated by any of the proposed mediators (total natural indirect effect for strength 0.01 (−1.14 to 1.80) and psychological factors 0.00 (−0.66 to 2.02)).
Conclusion We found an effect of pain on sports-related disability at 6 months which appears to be independent of lower extremity muscle strength, or depression/anxiety and knee confidence in adolescents with non-traumatic anterior knee pain.
Data availability statement
Data are available upon reasonable request. Not applicable.
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Twitter @Sinead_Holden, @mvanmiddelkoop
Collaborators Adolescent Knee Health group authors: Ewa M Roos, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark. Jens Lykkegaard Olesen, Center for General Practice at Aalborg University, Denmark.Thomas Graven-Nielsen, Center for Neuroplasticity and Pain (CNAP), Dept. of Health Science and Technology, The Faculty of Medicine, Aalborg University, Denmark. Lars Arendt Nielsen, Center for Neuroplasticity and Pain (CNAP), Dept. of Health Science and Technology, The Faculty of Medicine, Aalborg University, Denmark.Per Hölmich, Sports Orthopedic Research Center - Copenhagen (SORC-C), Department of Orthopaedic Surgery, Copenhagen University Hospital, Amager-Hvidovre, Denmark.Kristian Thorborg, Sports Orthopedic Research Center–Copenhagen (SORC-C), Department of Orthopaedic Surgery, Copenhagen University Hospital, Amager-Hvidovre, Denmark.Sten Rasmussen, Department of Clinical Medicine, Aalborg University, Denmark.Pascal Madeleine, Sports Sciences–Performance and Technology, Department of Health Science and Technology, The Faculty of Medicine, Aalborg University, Denmark.Mitchell Selhorst, Sports and Orthopedic Physical Therapy, Nationwide Children’s Hospital, USA.
Contributors All authors participated in the conception and design of the study. SH, HL, MSR and MvM developed the protocol prior to study initiation, with input from all group authors. SH and HL developed the statistical analysis approach, informed by directed acyclic graphs (DAGs). Members of the adolescent knee health group, MvM, MSR and SH were responsible for collection of the datasets included in this individual participant data analysis. SH and MSR were responsible for data agreements and acquiring the data. SH was responsible for data checking, harmonisation, conducting statistical analyses and presentation of the results. SH wrote the first draft of the manuscript. All authors critically revised the manuscript for important intellectual content and approved the final version of the manuscript. SH is the guarantor.
Competing interests None declared.
Patient and public involvement Patients and/or the public were involved in the design, or conduct, or reporting, or dissemination plans of this research. Refer to the Methods section for further details.
Provenance and peer review Not commissioned; externally peer reviewed.
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