Related Experiment Video
Updated: Jul 3, 2026
05:55
Tension-Free Weight-Bearing Model of Steroid-Induced Osteonecrosis of Femoral Head in Rats
Published on: September 27, 2024
The effect of weight loading and subsequent release from loading on the postnatal skeleton
Adi Reich1, Amnon Sharir, Elazar Zelzer
1Institute of Biochemistry and Nutrition, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, Israel. reich@agri.huji.ac.il
Bone
|July 16, 2008
Summary
External loading on young chicks’ bones negatively impacts growth plate development and bone properties. Despite a temporary catch-up, mechanical strength is compromised, highlighting risks during skeletal development.
Area of Science:
- Orthopedics
- Developmental Biology
- Biomechanics
Background:
- The relationship between mechanical load and bone properties is well-established for mature bones.
- This relationship is less understood in immature bones, particularly the cartilaginous growth plate during postnatal development.
Purpose of the Study:
- To investigate the effects of external loading on the growth plate and subsequent bone structural and mechanical properties in young, fast-growing chicks.
Main Methods:
- Tibial growth plates and bones from loaded and control chicks were analyzed using histological staining and quantitative PCR.
- Mechanical testing (three-point bending) and micro-computed tomography (micro-CT) were used to assess structural and mechanical properties.
Main Results:
- Externally loaded tibias were shorter with narrower growth plates initially.
- A 'catch-up' phenomenon was observed after load release, with increased growth plate thickness but unchanged chondrocyte differentiation gene expression.
- Upregulation of genes related to ossification and calcification occurred during catch-up.
- Loaded bones exhibited inferior mechanical and structural properties compared to controls after the catch-up period.
Conclusions:
- External loading during bone elongation adversely affects skeletal mechanical and structural integrity.
- The primary impact is on the growth plate, with consequences for bone phenotype appearing after a delay.
Related Concept Videos
01:09Changes in the Appendicular Skeleton with Age
The upper and lower limb initially develops as a small bulge called a limb bud, which appears on the lateral side of the early embryo. The upper limb bud appears near the end of the fourth week of development, with the lower limb bud appearing shortly after.
Initially, the limb buds consist of a core of mesenchyme covered by a layer of ectoderm. The ectoderm at the end of the limb bud thickens to form a narrow crest called the apical ectodermal ridge. This ridge stimulates the underlying...
Initially, the limb buds consist of a core of mesenchyme covered by a layer of ectoderm. The ectoderm at the end of the limb bud thickens to form a narrow crest called the apical ectodermal ridge. This ridge stimulates the underlying...
01:40Bone Remodeling
Bone remodeling is a continuous and balanced process of bone resorption by osteoclasts and bone formation by osteoblasts. In adults, it helps maintain bone mass and calcium homeostasis. While mechanical stress can stimulate turnover as part of the normal maintenance and reparative process, several hormones also regulate bone remodeling.
01:11Deformation of Member under Multiple Loadings
When a rod is made of different materials or has various cross-sections, it must be divided into parts that meet the necessary conditions for determining the deformation. These parts are each characterized by their internal force, cross-sectional area, length, and modulus of elasticity. These parameters are then used to compute the deformation of the entire rod.
In the case of a member with a variable cross-section, the strain is not constant but depends on the position. The deformation of an...
In the case of a member with a variable cross-section, the strain is not constant but depends on the position. The deformation of an...
01:18Residual Stresses in Bending
In the study of elastoplastic members subjected to bending moments, understanding the loading and unloading phases is crucial for assessing material behavior and structural integrity. During the loading phase, as the bending moment increases, the material initially responds elastically, adhering to Hooke's Law, where stress is directly proportional to strain. When the load exceeds the yield strength, plastic deformation occurs, resulting in permanent strain and deformation that remains even...
01:24Bone Formation by Endochondral Ossification
Bone formation, or ossification, begins around the sixth to seventh week of embryonic development. Most bones develop from a cartilaginous template through the process of endochondral ossification. Cartilage formation begins when clusters of mesenchymal cells differentiate into chondrocytes. These chondrocytes proliferate rapidly and secrete an extracellular matrix that becomes encased in a membrane called the perichondrium. The resulting cartilage model provides a template that resembles the...
01:29Bone Disorders
Aging and its effect on bone remodeling is the most common cause of bone disorders. In young and healthy people, bone deposition and resorption happen at an equal rate to maintain optimal bone health.
Bone deposition is also affected by the levels of sex hormones like estrogen and testosterone that promote osteoblast activity and bone matrix synthesis. When the level of these hormones decreases due to aging, it causes a reduction in bone deposition. As a result, bone resorption by osteoclasts...
Bone deposition is also affected by the levels of sex hormones like estrogen and testosterone that promote osteoblast activity and bone matrix synthesis. When the level of these hormones decreases due to aging, it causes a reduction in bone deposition. As a result, bone resorption by osteoclasts...