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Morphological characteristics of the developing proximal femur: A biomechanical perspective

Đurić Marija (Medicinski fakultet, Institut za anatomiju, Laboratorija za antropologiju, Beograd)
Milovanović Petar (Medicinski fakultet, Institut za anatomiju, Laboratorija za antropologiju, Beograd)
Đonić Danijela (Medicinski fakultet, Institut za anatomiju, Laboratorija za antropologiju, Beograd)
Minić Arsa (Evropski univerzitet, Američki medicinski fakultet u Beogradu, Beograd)
Hahn Michael (Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany)

Introduction. In contrast to a plethora of studies on the proximal femur in adults, its external and internal morphology in growing children has not been sufficiently analyzed. Objective. We analyzed changes in external and internal morphology of the proximal femur during growth and development to interpret the links between them and concepts of the human femoral biomechanics. Methods. We assessed external geometry, internal trabecular and cortical arrangement, and bone mineral density (BMD) of the proximal femur in 29 children (age at death from 1 month to 14 years) from archaeological context by using microscopic and radiographic methods. Results. The results showed that both the femoral neck width and length increased with age, with the femoral neck becoming more elongated, while the collo-diaphyseal angle decreased. A strong relationship between age and adjusted areal BMD was found, showing continuous increase during childhood. Parallel trabecular pattern at birth changed to mature three distinct trabecular groups (longitudinal – principal compressive, transversal – tensile and randomly scattered) starting from the age of 8 months. In older children the superior and inferior aspects of the femoral neck differently changed with growth, with medial neck having thicker cortex and trabeculae. Conclusion. In the light of bone adaptation principle, the observed changes in external and internal morphology are governed by mechanical forces acting on the developing femur. Our findings on the development of trabecular pattern and cortical distribution are compatible with recent views on the femoral biomechanics which point out the predominance of compressive stresses in the femoral neck, adaptation to shear stresses, multiaxial loading perspective, prevalence of muscle effects over body weight, and existence of adaptational eccentricity.

Keywords: proximal femur, growth, bone adaptation, mechanical loading

Projekat Ministarstva nauke Republike Srbije, br. 45005