Validity, reliability, and clinical usefulness of instruments for measuring thoracic kyphosis: a systematic review and meta-analysis.

Introduction: Thoracic hyperkyphosis is related to different health conditions, requiring precise evaluation in clinical settings. Several instruments have been proposed for assessing thoracic kyphosis, and previous studies have investigated their reliability and validity.

Aims: Systematically review studies evaluating the validity and reliability of instruments designed to measure thoracic kyphosis and classify their clinical utility.

Methods: MEDLINE and EMBASE (via Ovid) databases were used to search studies published until December 2023, and additional searches were conducted in Google Scholar and by hand search. Studies that analyzed the reliability and validity of noninvasive instruments for measuring thoracic kyphosis, regardless of population, study design, and language, were included. Two independent reviewers analyzed the titles, abstracts, and full text and assessed the methodological quality. Clinical utility was assessed using a 10-point scale.

Results: Seventy-two studies were included, and 15 instruments had their measurement properties explored: seven were grouped in a meta-analysis for validity, seven for intra-rater reliability, and six for inter-rater reliability. Despite the heterogeneity of estimated data, they presented a strong to moderate correlation with the gold standard and excellent intra- and inter-rater reliability. The instruments most frequently studied were the Flexicurve Angle and the Analog Inclinometer.

Conclusion: The meta-analysis demonstrated that the Analog Inclinometer, Flexicurve Angle and Index, Photogrammetry, Smartphone applications, and Spinal Mouse were valid and reliable for assessing thoracic kyphosis. Also, the utility analysis suggested that the Analog Inclinometer, Flexicurve Angle, and Smartphone applications are recommended for clinical settings.