{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,27]],"date-time":"2026-08-27T08:20:33Z","timestamp":1787818833799,"version":"build-2784847793"},"reference-count":35,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2026,8,27]],"date-time":"2026-08-27T00:00:00Z","timestamp":1787788800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Sensor-based three-dimensional surface topography provides non-invasive quantitative measurements of sagittal spinal alignment, but categorical posture profiles also depend on the thresholds and category structure used to transform continuous measurements. This cross-sectional methodological study compared an operationalised five-category classification with the nine-type Wilczy\u0144ski typology using the same sensor-derived thoracic kyphosis and lumbar lordosis measurements obtained with the DIERS Formetric III 4D rasterstereographic system. A total of 952 children aged 10\u201312 years (478 girls, 474 boys) were assessed. Category distributions were summarised descriptively, cross-classified in a 9 \u00d7 5 contingency table, and evaluated using Cram\u00e9r\u2019s V and Shannon entropy. The five-category classification concentrated 94.1% of participants in two categories, whereas the nine-type typology produced a more dispersed and even distribution. Normalised Shannon entropy was higher for the nine-type typology (0.85 vs. 0.57), and Cram\u00e9r\u2019s V was 0.55. Because both systems were deterministic transformations of the same sensor-derived measurements, these statistics were interpreted descriptively. The findings show that classification thresholds and category architecture substantially influence categorical representations derived from identical sensor-based measurements. Greater granularity and higher entropy indicate distributional differentiation, not superior clinical validity; independent external validation is required to establish clinical relevance.<\/jats:p>","DOI":"10.3390\/s26175408","type":"journal-article","created":{"date-parts":[[2026,8,27]],"date-time":"2026-08-27T08:02:27Z","timestamp":1787817747000},"page":"5408","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Three-Dimensional Surface Topography for Entropy-Based Comparison of Sagittal Postural Classifications in Children"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2564-8623","authenticated-orcid":false,"given":"Jacek","family":"Wilczy\u0144ski","sequence":"first","affiliation":[{"name":"Laboratory of Posturology, Collegium Medicum, Jan Kochanowski University of Kielce, 25-317 Kielce, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ma\u0142gorzata","family":"Gawlik","sequence":"additional","affiliation":[{"name":"Laboratory of Posturology, Collegium Medicum, Jan Kochanowski University of Kielce, 25-317 Kielce, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-5455-4301","authenticated-orcid":false,"given":"Katarzyna","family":"Bieniek","sequence":"additional","affiliation":[{"name":"Laboratory of Posturology, Collegium Medicum, Jan Kochanowski University of Kielce, 25-317 Kielce, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0008-8089-5022","authenticated-orcid":false,"given":"Paulina","family":"Szumilas","sequence":"additional","affiliation":[{"name":"Laboratory of Posturology, Collegium Medicum, Jan Kochanowski University of Kielce, 25-317 Kielce, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6876-5160","authenticated-orcid":false,"given":"Natalia","family":"Habik-Tatarowska","sequence":"additional","affiliation":[{"name":"Laboratory of Posturology, Collegium Medicum, Jan Kochanowski University of Kielce, 25-317 Kielce, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kamil","family":"Markowski","sequence":"additional","affiliation":[{"name":"Laboratory of Posturology, Collegium Medicum, Jan Kochanowski University of Kielce, 25-317 Kielce, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wiktoria","family":"\u015awietlak","sequence":"additional","affiliation":[{"name":"Laboratory of Posturology, Collegium Medicum, Jan Kochanowski University of Kielce, 25-317 Kielce, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5249-7157","authenticated-orcid":false,"given":"Agata","family":"Michalska","sequence":"additional","affiliation":[{"name":"Laboratory of Posturology, Collegium Medicum, Jan Kochanowski University of Kielce, 25-317 Kielce, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"676","DOI":"10.2106\/JBJS.22.00977","article-title":"Spinal sagittal alignment changes during childhood: Results of a national cohort analysis of 1,059 healthy children","volume":"105","author":"Pesenti","year":"2023","journal-title":"J. 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