Osteocyte lacunar strain determination using multiscale finite element analysis.

Area of Science:

• Biomechanical Engineering
• Cellular Mechanobiology
• Skeletal Biology

Background:

• Osteocytes are key mechanosensors in bone, regulating resorption and formation.
• Osteocyte activation by mechanical forces, including Wnt/β-catenin signaling, is heterogeneous.
• Previous finite element models often used simplified geometries and single osteocytes.

Purpose of the Study:

• To investigate how osteocyte lacunae size and orientation affect micro-heterogeneity in bone strain.
• To explain the observed heterogeneous patterns of osteocyte activation under mechanical loading.
• To develop multi-scale computational models of osteocyte mechanotransduction.

Main Methods:

• Developed microscale and nanoscale finite element (FE) models of osteocytes.
• Analyzed lacunar and perilacunar strain responses based on lacunar orientation and size.
• Utilized 3D confocal image stacks of mouse femur osteocytes for realistic geometries.
• Performed parametric analysis by varying perilacunar modulus.

Main Results:

• Lacunar strains decreased with increased perilacunar modulus, indicating stress shielding.
• Osteocytes aligned with the loading axis experienced lower strains than those perpendicular.
• Larger lacunae resulted in increased lacunar strains.
• FE models with multiple osteocytes, including realistic geometries, were employed.

Conclusions:

• Osteocyte lacunae orientation and size are critical factors in heterogeneous strain distribution.
• These factors contribute to the observed varied osteocyte activation patterns following mechanical loading.
• Understanding lacunar-level strain mechanics enhances knowledge of osteocyte mechanotransduction and bone adaptation.