3-Dimensional Buttocks Response to Sitting: A Case Report

Sharon Sonenblum, Stephen Sprigle, John Cathcart, John Winder

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)


Aim of the study: The aim of this study was to describe an individual’s 3-dimensional buttocks response to sitting. Within that exploration, we specificallyconsidered tissue (i.e., fat and muscle) deformations, including tissue displacementsthat have not been identified by research published to date.Materials and methods: The buttocks anatomy of an able-bodied female duringsitting was collected in a FONAR Upright MRI. T1-weighted Fast Spin Echo scanswere collected with the individual seated on a custom wheelchair cushion witha cutout beneath the pelvis (“unloaded”), and seated on a 300 foam cushion(“loaded”). 2D slices of the MRI were analyzed, and bone and muscle weresegmented to permit 3D rendering and analyses.Results: MRIs indicated a marked decrease in muscle thickness under the ischialtuberosity during loaded sitting. This change in thickness resulted from a combinationof muscle displacement and distortion. The gluteus and hamstrings overlappedbeneath the pelvis in an unloaded condition, enveloping the ischial tuberosity. Butthe overlap was removed under load. The hamstrings moved anteriorly, while thegluteus moved posterior-laterally. Under load, neither muscle was directly beneaththe apex of the ischial tuberosity. Furthermore, there was a change in muscleshape, particularly posterior to the peak of the ischial tuberosity.
Original languageEnglish
Pages (from-to)12-18
JournalJournal of Tissue Viability
Publication statusPublished (in print/issue) - 2013


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