Cortical bone development under the growth plate is regulated by mechanical load transfer

Area of Science:

• Orthopedics
• Bone Biology
• Biomechanics

Background:

• Longitudinal bone growth occurs at growth plates, producing trabecular bone that transitions into the cortical shell.
• The development of cortical bone and its relationship to mechanical stimuli are not fully understood.
• It is hypothesized that mechanical stimuli govern cortical bone development and share regulatory mechanisms with trabecular bone.

Purpose of the Study:

• To investigate the role of mechanical stimuli in the development of tibial cortical bone in growing pigs.
• To test the hypothesis that trabecular bone adaptation mechanisms can explain cortical bone development.
• To evaluate a mechanical stimulation theory for bone remodeling in both trabecular and cortical bone.

Main Methods:

• Longitudinal monitoring of tibial cortex development in growing pigs.
• Utilized micro-computer tomography and histology for detailed morphological analysis.
• Developed and applied a computer model based on mechanical stimulation theory.

Main Results:

• Observed gradual filling of trabecular pores with bone from the growth plate towards the diaphysis, increasing bone density and forming cortical bone.
• The computer model successfully predicted the observed morphological development of the tibial cortex.
• Demonstrated a transition of metaphyseal trabecular bone into diaphyseal cortical bone.

Conclusions:

• Merging of metaphyseal trabeculae into the cortical bone is likely regulated by mechanical stimuli.
• Cortical bone development in growing long bones can be explained as a form of trabecular bone adaptation.
• The findings suggest that distinct regulatory mechanisms for cortical and trabecular bone adaptation are not necessary.