How your bones
work

Bones constantly change throughout our lives. Learn how bones remodel themselves and stay strong.

Bones have many jobs in the body. They protect your organs, store minerals and make blood cells. They also give your body structure. This enables you to move around and do the activities you enjoy.

On this page, we explain how your bones work and how this changes when you have osteoporosis.

What happens inside your bones?

Bones change throughout your life.

Our bones are made up of:

  • a thick outer shell called cortical bone

  • strong scaffolding inside the bone called trabecular bone.

There are holes inside the scaffolding (trabecular bone).

There are also two types of cells inside your bones that work to keep them strong.

  • osteoclast cells break down old bone

  • osteoblast cells build new bone.

This process is called bone remodelling. As long as this process is in balance, your bones stay healthy and strong.

The diagram below shows the bone remodelling process.

Diagram showing the outer shell of the bone and scaffolding inside the bone, and two types of cells called osteoclast and osteoblast cells.
This diagram shows the outer shell of the bone and scaffolding inside the bone. It also show two types of cells called osteoclast and osteoblast cells.

What happens inside bones with osteoporosis?

When the bone remodelling process becomes out of balance, it causes changes to the bone. The shell of the bone gets thinner. The scaffolding inside the bone also thins and sometimes breaks down. This is osteoporosis.

Osteoporosis is a condition where your bones lose strength, making you more likely to break a bone (fracture).

The thinning happens on the inside of the bones. This means your bones won’t look any different. You also won’t feel any different.

The diagram below compares what happens to the outer shell (cortical bone) and scaffolding (trabecular bone) inside a normal bone and a bone with osteoporosis.

An illustration comparing a normal bone with a bone with osteoporosis
This diagram compares a normal bone with a bone with osteoporosis.


About this information

Last reviewed
1 April 2026
Next review
1 April 2029

Support Group

Support us as a member

From just £3 a month, you'll receive exclusive content, our member magazine, early access to events and more.

Laptop

Get news and updates via your inbox

Don't miss our expert insights, recipes, and tips for living well with osteoporosis.


Help fund vital support for people with osteoporosis

To change a life like Ann's, please give today

A lady called Ann who has osteoporosis