Reproducibility analysis and reference values for the tibiocalcaneal angle, the calcaneal-first metatarsal angle and the metatarsus adductus angle: systematic review and meta-analysis

Objectives: Primarily, this systematic review aimed to critically appraise, compare, and summarize or meta-analyze reliability coefficients of the tibiocalcaneal angle (TCA), the calcaneal – first metatarsal angle (C1MA) and the metatarsus adductus angle (MAA), and secondly, to estimate reference values of these measurements for adults. Methods: Systematic searches were conducted and were followed by study screening, data extraction, and appraisal of measurement property and quality of evidence according to the Consensus-based standards for the selection of health measurement instruments (COSMIN) guidelines. Results: Systematic searches identified 1532 potentially eligible studies; of these, 24 studies were included in the qualitative synthesis, and 22 were included in the meta-analyses. We ran meta-analyses of Intraclass Correlation Coefficients (ICC) and good reliability was found for the TCA – bisecting lines method (inter-rater ICC=0.951); TCA – 40% to 60% division method (intra-rater ICC=0.781) in adults; C1MA (intra-rater ICC=0.985) in young adults; MAA (intra-rater ICC=0.953) in young adults and (intra-rater ICC=0.973) in adults; and MAA (inter-rater ICC=0.942) in adults. Significance: TCA (bisecting lines method), C1MA and MAA demonstrated excellent intra-rater reliability. TCA (40-60% division method) and MAA demonstrated good and excellent inter-rater reliability, respectively. Nonetheless, these findings should be interpreted cautiously since the quality of evidence was low or moderate.