Children and adolescents with anterior knee pain can show construct validity and reliability with anterior knee pain scale, lower extremity functional scale and visual analogue scale

Structured Abstract and Levels of Evidence Background To investigate validity and reliability of the Anterior Knee Pain Scale, Lower Extremity Functional Scale and the Visual Analogue Scale Usual and Worst in 8-16-year-old children and adolescents with symptoms of Anterior knee pain commonly present to emergency and orthopaedic outpatients departments at Australian public tertiary/quaternary hospitals Method 50 participants aged 8-16 years with anterior knee pain participated in this prospective pre- and post-test methodological study. Measures employed included the Anterior Knee Pain Scale (AKPS), the Lower Extremity Functional Scale (LEFS), Visual Analogue Scale Usual (VAS-U) and Visual Analogue Scale Worst (VAS-W). Correlations between these outcome measures and the participant-perceived Global Rating of Change (GRC) categories (incomplete improvement, complete improvement) were determined. Results Test-retest reliability Intraclass Coefficient (ICC) values indicated good to excellent reliability in VAS-U (0.86), VAS-W (0.70), AKPS (0.98) and LEFS (0.98). Validity All measures showed convergent validity in comparison to the combined GRC assessment of complete score. The adjusted mean change scores had moderate evidence of a difference in AKPS (p=0.015) and LEFS (0.050); and very strong evidence for difference in VAS-U (p=0.006) and VAS-W (p<0.001) in the improvement groups, with a larger mean change exhibited in the complete improvement group. Responsiveness ANCOVA results indicated all the outcomes had larger adjusted mean scores in the complete group compared to the incomplete improvement group, suggesting these measures are responsive to measure change. Conclusion Anterior Knee pain is a common knee condition from child to adults. Just like in adults, questionnaires AKPS, LEFS, VAS-U, and VAS-W are valid, reliable and responsive measures in child and adolescent populations aged 8 - 16 years with anterior knee pain. These PROMs (Patient Reported Outcome Measures) can now be used in anterior knee pain conditions 8 years and above.