Morphogenetic development of trochlear groove and thigh muscles from embryo to fetus in humans.

Publisher: Public Library of Science Country of Publication: United States NLM ID: 101285081 Publication Model: eCollection Cited Medium: Internet ISSN: 1932-6203 (Electronic) Linking ISSN: 19326203 NLM ISO Abbreviation: PLoS One Subsets: MEDLINE

Original Publication: San Francisco, CA : Public Library of Science

Thigh*/embryology ; Thigh*/diagnostic imaging ; Muscle, Skeletal*/embryology ; Muscle, Skeletal*/diagnostic imaging ; Fetus* ; Morphogenesis*; Knee Joint/embryology ; Knee Joint/diagnostic imaging ; Femur/embryology ; Humans ; Female ; Magnetic Resonance Imaging ; Tomography, X-Ray Computed ; Pregnancy

Mechanical forces caused by fetal movements are essential for normal musculoskeletal development. However, the relationship between skeletal development and knee joint motion in utero remains unclear. We aimed to clarify the development of lower limb musculoskeletal structures during the embryonic and early fetal stages from a kinematic perspective and to compare muscle and skeletal developmental processes. We analyzed 29 human embryonic and fetal specimens. Using phase-contrast X-ray computed tomography and magnetic resonance imaging, we analyzed the morphogenesis of the knee joint components, trochlear groove angle, and hypothetical joint motion of the thigh muscles in three dimensions. To analyze chronological morphogenesis, Procrustes analysis was performed, and Principal component analysis and linear discriminant analysis were subsequently conducted using the Procrustes coordinates. The trochlear groove angle on the plane vertical to the femoral axis decreased from approximately 160° to 130° until 120 mm Crown-rump length (CRL) and remained constant until 185 mm CRL. All hypothetical joint motions increased slowly between 30 and 100 mm CRL, whereas rapidly after approximately 100 mm CRL. The protrusions of the lateral femoral condyle became more pronounced from fetal stage as they grew. The timing of the onset of fetal movement and the increase in muscle mass and joint motion during early pregnancy were consistent with those of previous studies, and the timing of the angle stabilization occurred almost simultaneously with the rapid increase in femoral muscle mass and hypothesized joint motion. It suggested that stabilization of joint morphology enables smooth joint motion, which leads to an increase in muscle mass and joint motion.
(Copyright: © 2026 Ishikawa et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The authors have declared that no competing interests exist.

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Date Created: 20260202 Date Completed: 20260202 Latest Revision: 20260205

20260205

PMC12863510

10.1371/journal.pone.0339167

41628144