Download MBBS Orthopaedics PPT 7 Fracture Healing Lecture Notes

FRACTURE HEALING

DEFINITON OF FRACTURE

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It's a break in the continuity of

bone

With partial or total disruption of

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blood supply to the region of bone

Seen radiologically as uni or

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bicortical break.


DEFINITION OF FRACTURE REPAIR

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Is a systematic and organized

cascade of events for the

regeneration of tissue with

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influence of local and systematic

factors

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FRACTURE REPAIR

It's a regenerative process rather

than healing

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As the defect is replaced by new

bone rather than scar tissue.

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FRACTURE REPAIR

It's a continuous process in which

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bone is

Formed

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Replaced

Remodeled

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FACTORS AFFECTING FRACTURE REPAIR

Local factors
1. Type of bone (normal or pathological)
2. Type of fracture ( open or closed)

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3. Intra articular fracture
4. Surrounding soft tissue injury
5. Single or both bone fracture
6. Local bone pathology like cyst
7. Infection

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8. Venous stasis
9. Type of treatment and fixation


FACTORS AFFECTING FRACTURE REPAIR

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Systemic factors

1. Age

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2. Activity level

3. Nutritional status

4. Hormonal factors

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5. Vitamin and mineral deficiency

6. Diabetes mel itus

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7. Patient on drugs like chemotherapy,

steroids

8. Smoking

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9. Alcohol abuse

10. Head injury

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TYPES OF FRACTURE REPAIR

3 types
1. Intramembranous repair (direct bone healing)

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2. Creeping substitution

3. Repair with bone callus formation (indirect bone healing)

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INTRA MEMBERANEOUS REPAIR

? No callus formation
? Bone heals directly
? Seen in rigid fixation such as

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plating

? This occurs when the gap after

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fixation is below 500 microns

? Cutting cones crosses from one

side to another

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INTRA MEMBERANEOUS REPAIR

Healing passes through following

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stages

1. Resorption of bone ends- due to

compression at fracture site

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2. Fibrous tissue formation-

formed from healing hematoma

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composed of collagen
3. Maturation to lamellar bone-

Haversian remodeling occurs across fracture site.

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Osteoclastic front is followed by osteoblastic

ossification and laying of thin capillaries.

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CREEPING SUBSTITUTION

Primarily seen in cancellous bone
Seen around intra and peri

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articular fractures

It's a process of resorption of trabecular

network

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Lying of new bone by appositional ossification

on the surface of scaffold

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The inflammatory cells and granulation tissue

creeps and new bone is thus formed

CREEPING SUBSTITUTION

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This sandwich of necrotic bone surrounded by

viable new bone is remodeled

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Gross architecture of the bone is maintained

Scaffold is copy pasted by new living bone

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SECONDARY BONE HEALING

This refers to passing through the stage

of callus formation

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Callus is pre-ossification cartilage tissue

which is formed in response to

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controlled motion over fracture site

SECONDARY BONE HEALING

Three stages

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1. Reactive (Inflammatory) stage
a)

Hematoma formation

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b)

Granulation tissue formation

2. Reparative stage

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a)

Cal us formation soft cal us

hard cal us

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a)

Consolidation

3.Remodelling stage

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INFLAMATORY STAGE

Hematoma formation

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Blood leaks into the surrounding tissue due to

disruption of vessels, periosteum and

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endosteum

Induces local inflammatory response

Starts regional acceleratory phenomenon

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INFLAMATORY STAGE

Stage of hematoma formation

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Osteoblast comes from bone

Osteoclast come from

marrow and mesenchymal

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hematopoietic cel s of bone

cel s from cambium layer of

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marrow

periosteum

BMP

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BMP

Migrate to the fracture focus

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TGF-beta and platelet

derived growth factor

Colony forming unit fibroblast

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Granulation tissue
INFLAMATORY STAGE

Granulation tissue formation

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vessels

hematoma

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Vascular endothelial growth factor and

fibroblast growth factor

Fibro vascular granulation tissue-

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type II collagen

This stage

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last for 2

weeks

REPARATIVE STAGE

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It comprises of two stages-
Callus formation stage soft callus (primary callus)

hard callus

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Consolidation (lamellar bone deposition)


REPARATIVE STAGE

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Callus formation-
It's a regenerative tissue formed in response to
micro motion at the injury site.
The formation is combined effect of four distinct

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healing responses
?Bone marrow
?Bone cortex
?Periosteum

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?External soft tissue

REPARATIVE STAGE

Soft callus-

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Starts forming after 2 weeks
4 types-
1. Periosteal bridging callus
2. Intramedullary callus
3. Intercortical uniting callus

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4. External soft tissue callus
REPARATIVE STAGE

Periosteal bridging callus

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Cel s from cambium layer develop into osteoblast and deposit the

organic matrix

Intramedullary callus

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Laid down from inside the bone

It's a double concave shape

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Predominant response during gap repair

REPARATIVE STAGE

Intercortical uniting callus

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Occupy the space between opposed cortices of fracture ends

External soft tissue response

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Develop from vascular mesenchymal tissue like muscles and is important in

fracture repair

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REPARATIVE STAGE

Hard callus
Transformation of woven bone into primary

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lamellar bone

Commences in 4th week and finishes around 16th

week.

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The amount of callus formed depends on the

oxygen tension and strain pattern (treatment)

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REPARATIVE STAGE

Consolidation
(lamellar bone deposition)
Type II collagen is replaced by type I collagen.

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Followed by mineralization of the collagen.

(osteoid)

Enchondral ossification- formation of lamellar

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bone over hyaline cartilage
Bone substitution- formation of lamellar bone

over woven bone.

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REMODELLING

Recycling of minerals (calcium and

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Osteoclast with their cutting cones

phosphate)

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Conversion of primary lamel ar bone

Resorbs the bone and form howship lacunae

Secondary lamel ar bone

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According to the functional load and

May last upto 7 years

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stress(wolff's law)

Osteoblast then grows and lay down the

lamel ar bone

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FACTORS AFFECTING REMODELLING

? Proximity to appendicular skeleton
? Juxta physeal deformity (more bone

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deposition on concave side and bone

resorption at convex side). So any

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deformity near the physis have more

chances of remodeling

? Presence of deformity near the

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particular physis. Remodeling is more

when present near proximal humerus

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than distal humerus.


FACTORS AFFECTING REMODELLING

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? Fracture location- fracture near

the metaphysis remodels faster.

? Age of the patient

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? Pathological bone

FACTORS AFFECTING FRACTURE REPAIR

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Method of treatment

Affect of age and site of fracture

Absolute stability, rigid fixation, low strain

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environment

Fracture heals faster in children by 1.5 to 2 times

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than in old age

Primary fracture repair
FACTORS AFFECTING FRACTURE REPAIR

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Smoking

Radiation

Oste oblastic

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osteoporosis

can cause

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activity

inhibits

1. Osteoradionecrosis

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induces

2. Fractures

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smoking

3. Bone growth changes

inhibits

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Inhibits

4. Radiation induced cancers

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Estrogen

activity

Antioxidant

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properties of

vitamin C and

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E

BONE GRAFT AND BONE GRAFT SUBSTITUTE

Indications-

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? Skeletal defects after tumor resection
? Reconstruction of bone defects after failed joint arthroplasty
? Reconstruction of congenital bone defects
? Obliteration of cystic cavity of bone
? Repair of fresh fractures with bone loss.

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? Treatment of non union
? Arthrodesis of joints.
BONE GRAFT AND BONE GRAFT SUBSTITUTE

Provide

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Latticework for ingrowth of host bone- osteoconductive

Supply living osteogenic cells- osteogenic property

Growth factors to induce bone formation- osteoinduction

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BONE GRAFT AND BONE GRAFT SUBSTITUTE

Types of graft-

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1. Cancellous graft

2. Cortical graft

3. Cortico- cancellous graft

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4. Auto graft

5. Syngraft

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6. Allograft

7. Xenograft

8. Synthetic graft

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BONE GRAFT AND BONE GRAFT SUBSTITUTE

Sites of obtaining cancellous bone auto graft
1. Iliac crest
2. Proximal tibia

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3. Trochanteric region of femur
4. Distal condyle of femur
5. Olecranon process of ulna
6. Distal radius styloid process.

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BONE GRAFT AND BONE GRAFT SUBSTITUTE

Sites for obtaining cortical bone auto graft
1. Fibula
2. Tibia proximal half

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BONE GRAFT AND BONE GRAFT SUBSTITUTE

Types of allograft-
1. Fresh
2. Fresh frozen

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3. Freeze dried (lyophilized)
4. Osteochondral allograft
5. Large composite graft