Authors
- Sonja Ostojić – Faculty of Dental Medicine and Health Osijek, J. J. Strossmayer University Osijek, Osijek, Croatia
- Ivan Jurak – University of Applied Health Sciences Zagreb, Department of Physiotherapy, Zagreb, Croatia; Alma Mater Europaea University – European Centre Maribor, Maribor, Slovenia
DOI
https://doi.org/10.65241/wh.9.1.3
Article type:
Original Scientific Paper
Abstract:
Background: The infrasternal angle (ISA) has recently gained attention as a potentially relevant clinical and kinematic parameter because of its associations with breathing patterns, abdominal muscle function, and thoracic–pelvic interaction. However, the absence of a standardized measurement protocol and the variability of manual techniques limit its broader clinical and research application. Photogrammetry using Kinovea software may represent a practical and objective alternative, although its application for ISA measurement has not yet been systematically investigated. This study aimed to compare manual goniometry and Kinovea-based photogrammetry in assessing ISA in healthy young adults, with the hypothesis of a high level of inter-method agreement.
Methods: ISA was measured in 94 healthy young adults using manual goniometry and frontal photographs analyzed with Kinovea software. Continuous data were summarized using descriptive statistics, while normality was assessed using the Shapiro–Wilk test. Systematic differences between methods were evaluated with a paired-samples t-test. Absolute agreement at the individual level was quantified using a two-way single-measure intraclass correlation coefficient (ICC). Measurement error was characterized by the standard error of measurement (SEM) and minimal detectable change at the 95% confidence level (MDC95). Agreement between methods was further examined using Bland–Altman analysis.
Results: The ICC (2,1) for absolute agreement was 0.955 (95% CI 0.941–0.970), indicating excellent agreement between methods. SEM was 2.54°, and MDC95 was 7.04°. Bland–Altman analysis demonstrated a mean bias of 1.63°, with 95% limits of agreement ranging from –4.84° to 8.09°, with most values falling within these limits.
Conclusions: Kinovea photogrammetry demonstrates excellent agreement with manual goniometry, with small and consistent inter-method differences below the MDC95 threshold. These findings suggest that Kinovea represents a reliable and methodologically consistent alternative to manual goniometry for ISA assessment, offering advantages such as objective documentation, reduced examiner dependency, and suitability for research, education, and large-scale data collection.
Keywords:
Infrasternal angle, goniometry, photogrammetry.