MBBS Year
1st Year
Subject
What Is Usually Asked
Bone structure, blood supply, ossification
Resource HubAll Years (1st-Final)All UniversitiesFracture Healing
Fracture Healing: Notes, PPT and PYQs for MBBS
Fracture healing is the process by which a broken bone repairs itself and restores its original structure and strength. Bone is one of the few tissues that heals by regeneration rather than scar formation. Fracture healing is a classic short note in 2nd Year Pathology, and its complications and treatment are examined in Final Year Orthopaedics within General Surgery.
SME-reviewed. Updated 2026.
Open in GeckoMed for PPT slides and notes. Quick Summary: What You Need to Know for University Exams
- Bone heals by primary (direct) or secondary (indirect) healing.
- Secondary healing is the usual type and forms a callus; primary healing occurs with rigid fixation and close contact of fragments.
- Classic stages of secondary healing: haematoma and inflammation, soft callus, hard callus, and remodelling.
- Remodelling follows Wolff's law: bone adapts to the loads placed on it.
- Healing is helped by good blood supply, immobilisation and nutrition; it is delayed by movement at the fracture site, infection, smoking and poor blood supply.
- Important complications: delayed union, non-union and malunion.
- Children's fractures heal faster and remodel better than adults' fractures.
Fracture Healing Across MBBS Subjects
| MBBS Year | Subject | What Is Usually Asked |
|---|---|---|
| 1st Year | Anatomy | Bone structure, blood supply, ossification |
| 1st Year | Physiology | Calcium metabolism, hormones affecting bone |
| 2nd Year | Pathology | Stages of fracture healing, factors affecting healing |
| Final Year | General Surgery (Orthopaedics) | Clinical union, delayed union, non-union, malunion, management |
MBBS Year
1st Year
Subject
What Is Usually Asked
Calcium metabolism, hormones affecting bone
MBBS Year
2nd Year
Subject
What Is Usually Asked
Stages of fracture healing, factors affecting healing
MBBS Year
Final Year
What Is Usually Asked
Clinical union, delayed union, non-union, malunion, management
Definition and Types of Bone Healing
Definition: Fracture healing is the biological process by which continuity of fractured bone is restored through formation of new bone that is later remodelled to its original shape and strength.
Primary Versus Secondary Healing
| Feature | Primary (Direct) Healing | Secondary (Indirect) Healing |
|---|---|---|
| Conditions | Anatomical reduction and rigid fixation (such as compression plating) | Some movement at the fracture site (casts, intramedullary nails, external fixators) |
| Callus | No visible external callus | Visible callus |
| Mechanism | Cutting cones of osteoclasts and osteoblasts cross the fracture line directly | Bone forms through an intermediate cartilage callus |
| Frequency | Less common | Most common |
Feature
Conditions
Primary (Direct) Healing
Anatomical reduction and rigid fixation (such as compression plating)
Secondary (Indirect) Healing
Some movement at the fracture site (casts, intramedullary nails, external fixators)
Feature
Callus
Primary (Direct) Healing
No visible external callus
Secondary (Indirect) Healing
Visible callus
Feature
Mechanism
Primary (Direct) Healing
Cutting cones of osteoclasts and osteoblasts cross the fracture line directly
Secondary (Indirect) Healing
Bone forms through an intermediate cartilage callus
Feature
Frequency
Primary (Direct) Healing
Less common
Secondary (Indirect) Healing
Most common
Stages of Secondary Fracture Healing
| Stage | Approximate Timing | Key Events |
|---|---|---|
| 1. Haematoma formation and inflammation | First few days | Torn vessels form a haematoma; bone ends die back slightly; inflammatory cells and growth factors are released |
| 2. Soft callus (fibrocartilaginous callus) | About the first 2 to 3 weeks | Granulation tissue replaces the haematoma; fibroblasts and chondroblasts form fibrocartilage, bridging the fragments |
| 3. Hard callus (bony callus) | Weeks to about 3 months | Woven bone replaces cartilage by endochondral ossification; the fracture becomes clinically united |
| 4. Remodelling | Months to years | Woven bone is replaced by lamellar bone; the medullary canal is restored; shape adapts to stresses |
Stage
1. Haematoma formation and inflammation
Approximate Timing
First few days
Key Events
Torn vessels form a haematoma; bone ends die back slightly; inflammatory cells and growth factors are released
Stage
2. Soft callus (fibrocartilaginous callus)
Approximate Timing
About the first 2 to 3 weeks
Key Events
Granulation tissue replaces the haematoma; fibroblasts and chondroblasts form fibrocartilage, bridging the fragments
Stage
3. Hard callus (bony callus)
Approximate Timing
Weeks to about 3 months
Key Events
Woven bone replaces cartilage by endochondral ossification; the fracture becomes clinically united
Stage
4. Remodelling
Approximate Timing
Months to years
Key Events
Woven bone is replaced by lamellar bone; the medullary canal is restored; shape adapts to stresses
Timings vary with the bone, age, fracture type and treatment. Use the stages and the values in your prescribed textbook.
Some textbooks describe five stages: haematoma, inflammation and cellular proliferation, callus formation, consolidation and remodelling. Learn the version in your textbook, but the underlying sequence is the same.
Wolff's Law
Bone is laid down where it is needed and removed where it is not, according to the mechanical stresses it bears. This explains how an angulated fracture in a child can straighten over time.
(Examiner may ask you to draw the stages of fracture healing.)
Clinical and Radiological Union
| Type | Signs |
|---|---|
| Clinical union | No tenderness at the fracture site, no abnormal movement, and the limb can bear load without pain |
| Radiological union | Bridging callus or trabeculae crossing the fracture line on X-ray, usually on at least three of four cortices in two views |
Type
Clinical union
Signs
No tenderness at the fracture site, no abnormal movement, and the limb can bear load without pain
Type
Radiological union
Signs
Bridging callus or trabeculae crossing the fracture line on X-ray, usually on at least three of four cortices in two views
Approximate Union Times (Classical Teaching)
| Situation | Approximate Time |
|---|---|
| Upper limb, spiral fracture, adult | About 3 weeks to callus, about 6 weeks to union |
| Lower limb | About twice the upper limb times |
| Transverse fractures | Longer than spiral fractures |
| Children | Faster than adults |
Situation
Upper limb, spiral fracture, adult
Approximate Time
About 3 weeks to callus, about 6 weeks to union
Situation
Lower limb
Approximate Time
About twice the upper limb times
Situation
Transverse fractures
Approximate Time
Longer than spiral fractures
Situation
Children
Approximate Time
Faster than adults
These are teaching guides (Perkins' timetable is a commonly used rule of thumb). Actual healing depends on many factors.
Factors Affecting Fracture Healing
| Category | Factors That Help | Factors That Delay |
|---|---|---|
| Local | Good blood supply, stable fixation, close apposition of fragments, cancellous bone | Poor blood supply (such as scaphoid waist, neck of femur, lower third of tibia), excessive movement, soft tissue interposition, infection, wide gap, pathological bone, open fracture |
| Systemic | Young age, good nutrition, adequate vitamin D and calcium | Old age, diabetes, smoking, corticosteroids, malnutrition, anaemia, some NSAIDs (debated) |
Category
Local
Factors That Help
Good blood supply, stable fixation, close apposition of fragments, cancellous bone
Factors That Delay
Poor blood supply (such as scaphoid waist, neck of femur, lower third of tibia), excessive movement, soft tissue interposition, infection, wide gap, pathological bone, open fracture
Category
Systemic
Factors That Help
Young age, good nutrition, adequate vitamin D and calcium
Factors That Delay
Old age, diabetes, smoking, corticosteroids, malnutrition, anaemia, some NSAIDs (debated)
Bones Prone to Poor Healing
| Site | Reason |
|---|---|
| Neck of femur (intracapsular) | Blood supply to the head is disrupted; risk of avascular necrosis |
| Waist of scaphoid | Retrograde blood supply; proximal fragment may undergo avascular necrosis |
| Lower third of tibia | Poor muscle cover and blood supply |
| Talus | Retrograde blood supply |
Site
Neck of femur (intracapsular)
Reason
Blood supply to the head is disrupted; risk of avascular necrosis
Site
Waist of scaphoid
Reason
Retrograde blood supply; proximal fragment may undergo avascular necrosis
Site
Lower third of tibia
Reason
Poor muscle cover and blood supply
Site
Talus
Reason
Retrograde blood supply
Complications of Fracture Healing
| Complication | Definition | Common Causes | Management Principles |
|---|---|---|---|
| Delayed union | Healing takes longer than expected for that fracture | Infection, poor blood supply, inadequate immobilisation | Treat the cause, continued immobilisation, sometimes bone grafting |
| Non-union | Healing has stopped without bony union | Excess movement, gap, infection, poor blood supply, soft tissue interposition | Stable fixation with or without bone grafting |
| Malunion | Healing in a faulty position (angulation, rotation, shortening) | Inadequate reduction or loss of reduction | Corrective osteotomy if function is affected |
| Pseudarthrosis | A false joint at a non-union site | Long-standing non-union with movement | Excision of the false joint, fixation and grafting |
Complication
Delayed union
Definition
Healing takes longer than expected for that fracture
Common Causes
Infection, poor blood supply, inadequate immobilisation
Management Principles
Treat the cause, continued immobilisation, sometimes bone grafting
Complication
Non-union
Definition
Healing has stopped without bony union
Common Causes
Excess movement, gap, infection, poor blood supply, soft tissue interposition
Management Principles
Stable fixation with or without bone grafting
Complication
Malunion
Definition
Healing in a faulty position (angulation, rotation, shortening)
Common Causes
Inadequate reduction or loss of reduction
Management Principles
Corrective osteotomy if function is affected
Complication
Pseudarthrosis
Definition
A false joint at a non-union site
Common Causes
Long-standing non-union with movement
Management Principles
Excision of the false joint, fixation and grafting
Types of Non-Union
| Type | Features |
|---|---|
| Hypertrophic | Abundant callus but no bridging ("elephant foot"); biology is good, stability is poor; needs stable fixation |
| Atrophic | Little or no callus; poor biology and blood supply; needs fixation plus bone grafting |
Type
Hypertrophic
Features
Abundant callus but no bridging ("elephant foot"); biology is good, stability is poor; needs stable fixation
Type
Atrophic
Features
Little or no callus; poor biology and blood supply; needs fixation plus bone grafting
Other Complications of Fractures
- Avascular necrosis
- Infection (osteomyelitis), especially in open fractures
- Compartment syndrome
- Fat embolism
- Joint stiffness and myositis ossificans
- Complex regional pain syndrome (Sudeck's atrophy)
Management Principles of Fractures
- Reduction: Restore alignment (closed or open)
- Immobilisation (holding): Casts, splints, traction, internal or external fixation
- Rehabilitation: Restore movement and function
Related: Colles fracture, a classic example of fracture management.
Fracture Healing in Children
- Thick, active periosteum gives rapid callus formation
- Greater capacity for remodelling, especially near the growth plate and in the plane of joint movement
- Rotational deformities do not remodel well
- Growth plate injuries (Salter-Harris classification) can cause growth disturbance
Quick Viva Questions
Q: What are the stages of secondary fracture healing? A: Haematoma and inflammation, soft callus, hard callus, and remodelling.
Q: What is Wolff's law? A: Bone remodels according to the mechanical stresses placed on it.
Q: What is the difference between delayed union and non-union? A: In delayed union healing is slower than expected but still progressing; in non-union healing has stopped.
Q: When does primary bone healing occur? A: With anatomical reduction and rigid fixation, such as compression plating, with no visible callus.
Q: Name two fracture sites prone to avascular necrosis. A: The neck of the femur and the waist of the scaphoid.
Q: What is malunion? A: Healing of a fracture in a faulty position.
How Fracture Healing Appears in MBBS University Exams
Typical question styles (not attributed to specific papers or years):
- "Describe the stages of fracture healing. Add a note on the factors affecting it." (Long essay or short note, Pathology)
- "Write a short note on non-union of fractures." (Short note, Orthopaedics)
- "Write a short note on complications of fractures." (Short note)
- "Differentiate primary and secondary bone healing." (Short answer)
- "Write a short note on avascular necrosis." (Short note)
Frequently Asked Questions
How long does a fracture take to heal?
It varies with the bone, the type of fracture, age and treatment. As a rough guide, upper limb fractures in adults unite in about 6 weeks and lower limb fractures take about twice as long; children heal faster.
What is the most important factor in fracture healing?
Adequate blood supply and appropriate stability at the fracture site are the key local factors.
Can I download the fracture healing PPT for my presentation?
Yes. Use the Download PPT button at the top of this page. The GeckoMed app also gives offline access to the slides and notes.
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