Bone repair involves hematoma and callus formation, and remodeling (clinical)

Hormonal Controls

Determine when remodeling occurs.

Mechanical Stress

Determines where remodeling occurs.

Bone Mass Balance

In healthy young adults, bone deposition and resorption are roughly equal.

Factors Affecting Bone Balance – Genetics and environment can cause bone loss or bone formation.

Nondisplaced Fracture

Bone ends remain in normal alignment.

Displaced Fracture

Bone ends are out of normal alignment.

Complete Fracture

Bone is broken all the way through.

Incomplete Fracture

Bone is not broken all the way through.

Open (Compound) Fracture

Broken bone penetrates the skin.

Closed (Simple) Fracture

Broken bone does not penetrate the skin.

Fracture Treatment

Reduction

Realignment of broken bone ends.

Fracture Treatment

Closed (external) reduction

Physician manually moves bone ends back into position.

Fracture Treatment

Open (Internal) Reduction

Surgery uses screws and plates to hold broken bone ends together.

Fracture Treatment

Fracture Immobilization

A cast or traction keeps the bone in place while it heals.

Fracture Treatment

Fracture Healing Time

Simple fractures in young adults usually heal in 6–8 weeks. Larger bones and older adults take longer.

Four Stages of Fracture Repair

Stage 1

Hematoma Formation – Torn blood vessels cause blood to clot at the fracture site, forming a hematoma. Swelling, pain, and inflammation occur.

Four Stages of Fracture Repair

Stage 2

Fibrocartilaginous Callus Formation – New blood vessels grow into the clot. Fibroblasts produce collagen, and chondroblasts produce cartilage, forming a soft callus that connects the broken ends.

Soft Callus

A mass of collagen and cartilage that splints the broken bone together.

Four Stages of Fracture Repair

Stage 3

Bony Callus Formation – Osteoblasts form new spongy bone, gradually replacing the soft callus with immature bone. A firm union usually forms in about two months.

Bony Callus

Immature bone that replaces the fibrocartilaginous callus and connects the broken bone fragments.

Four Stages of Fracture Repair

Stage 4

Bone Remodeling – Excess material and dead bone are removed. Compact bone rebuilds the shaft, restoring the bone's original structure.

What Helps Guide Bone Remodeling After a Fracture?

Mechanical stresses help the repaired bone return to its original shape and structure.