Objective: The objective of this study was to investigate the stresses and displacements of the sacroiliac joint as well as ligament strains under 3 conditions of manipulation of hip and knee flexion (MHKF).
Methods: A pelvis-femur finite element model was established. Three MHKFs were applied to the model, which involved 3 states of the hip joint. The 3 states were as follows - MHKF-F1: the hip was flexed to 155° and abducted to 35°; MHKF-F2: the hip was flexed to 155° and placed at neutral place; MHKF-F3: the hip was flexed to 155° and intorted to 35°. The stresses and displacements of the sacroiliac joint were calculated, and ligament strains were analyzed.
Results: Under 3 MHKFs, the maximum stresses on the pelvis produced by MHKF-F1, F2, and F3 were 154.1, 123.4, and 180.3 MPa, respectively. The maximum stresses on the sacroiliac joint produced by MHKF-F1, F2, and F3 were 3.9, 3.3, and 2.8 MPa, respectively. The sacroiliac joint displacements were all less than 0.252 mm under the 3 MHKFs. MHKF-F1 produced the largest displacement. Different levels of ligament strain were observed, and the greatest ligament strains were caused by MHKF-F3.
Conclusions: Three MHKFs produced different degrees of stress in the pelvis and sacroiliac joint. Three MHKFs could produce small sacroiliac joint displacements. However, they could produce different levels of ligament strains, and MHKF-F3 produced the greatest ligament strain.
Author keywords: Finite Element Analysis; Musculoskeletal Manipulations; Sacroiliac Joint.
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