Download MBBS Orthopaedics PPT 7 Fracture Healing Lecture Notes

Download MBBS (Bachelor of Medicine, Bachelor of Surgery) Orthopaedics PPT 7 Fracture Healing Lecture Notes


FRACTURE HEALING

DEFINITON OF FRACTURE

It's a break in the continuity of

bone

With partial or total disruption of

blood supply to the region of bone

Seen radiologically as uni or

bicortical break.


DEFINITION OF FRACTURE REPAIR

Is a systematic and organized

cascade of events for the

regeneration of tissue with

influence of local and systematic

factors

FRACTURE REPAIR

It's a regenerative process rather

than healing

As the defect is replaced by new

bone rather than scar tissue.


FRACTURE REPAIR

It's a continuous process in which

bone is

Formed



Replaced

Remodeled

FACTORS AFFECTING FRACTURE REPAIR

Local factors
1. Type of bone (normal or pathological)
2. Type of fracture ( open or closed)
3. Intra articular fracture
4. Surrounding soft tissue injury
5. Single or both bone fracture
6. Local bone pathology like cyst
7. Infection
8. Venous stasis
9. Type of treatment and fixation


FACTORS AFFECTING FRACTURE REPAIR

Systemic factors

1. Age

2. Activity level

3. Nutritional status

4. Hormonal factors

5. Vitamin and mineral deficiency

6. Diabetes mel itus

7. Patient on drugs like chemotherapy,

steroids

8. Smoking

9. Alcohol abuse

10. Head injury

TYPES OF FRACTURE REPAIR

3 types
1. Intramembranous repair (direct bone healing)

2. Creeping substitution

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


INTRA MEMBERANEOUS REPAIR

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

plating

? This occurs when the gap after

fixation is below 500 microns

? Cutting cones crosses from one

side to another

INTRA MEMBERANEOUS REPAIR

Healing passes through following

stages

1. Resorption of bone ends- due to

compression at fracture site

2. Fibrous tissue formation-

formed from healing hematoma

composed of collagen
3. Maturation to lamellar bone-

Haversian remodeling occurs across fracture site.

Osteoclastic front is followed by osteoblastic

ossification and laying of thin capillaries.


CREEPING SUBSTITUTION

Primarily seen in cancellous bone
Seen around intra and peri

articular fractures

It's a process of resorption of trabecular

network

Lying of new bone by appositional ossification

on the surface of scaffold

The inflammatory cells and granulation tissue

creeps and new bone is thus formed

CREEPING SUBSTITUTION

This sandwich of necrotic bone surrounded by

viable new bone is remodeled

Gross architecture of the bone is maintained

Scaffold is copy pasted by new living bone


SECONDARY BONE HEALING

This refers to passing through the stage

of callus formation

Callus is pre-ossification cartilage tissue

which is formed in response to

controlled motion over fracture site

SECONDARY BONE HEALING

Three stages
1. Reactive (Inflammatory) stage
a)

Hematoma formation

b)

Granulation tissue formation

2. Reparative stage
a)

Cal us formation soft cal us

hard cal us
a)

Consolidation

3.Remodelling stage


INFLAMATORY STAGE

Hematoma formation

Blood leaks into the surrounding tissue due to

disruption of vessels, periosteum and

endosteum

Induces local inflammatory response

Starts regional acceleratory phenomenon

INFLAMATORY STAGE

Stage of hematoma formation

Osteoblast comes from bone

Osteoclast come from

marrow and mesenchymal

hematopoietic cel s of bone

cel s from cambium layer of

marrow

periosteum

BMP

BMP

Migrate to the fracture focus

TGF-beta and platelet

derived growth factor

Colony forming unit fibroblast

Granulation tissue
INFLAMATORY STAGE

Granulation tissue formation

vessels

hematoma

Vascular endothelial growth factor and

fibroblast growth factor

Fibro vascular granulation tissue-

type II collagen

This stage

last for 2

weeks

REPARATIVE STAGE

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

hard callus

Consolidation (lamellar bone deposition)


REPARATIVE STAGE

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

healing responses
?Bone marrow
?Bone cortex
?Periosteum
?External soft tissue

REPARATIVE STAGE

Soft callus-
Starts forming after 2 weeks
4 types-
1. Periosteal bridging callus
2. Intramedullary callus
3. Intercortical uniting callus
4. External soft tissue callus
REPARATIVE STAGE

Periosteal bridging callus

Cel s from cambium layer develop into osteoblast and deposit the

organic matrix

Intramedullary callus

Laid down from inside the bone

It's a double concave shape

Predominant response during gap repair

REPARATIVE STAGE

Intercortical uniting callus

Occupy the space between opposed cortices of fracture ends

External soft tissue response

Develop from vascular mesenchymal tissue like muscles and is important in

fracture repair


REPARATIVE STAGE

Hard callus
Transformation of woven bone into primary

lamellar bone

Commences in 4th week and finishes around 16th

week.

The amount of callus formed depends on the

oxygen tension and strain pattern (treatment)

REPARATIVE STAGE

Consolidation
(lamellar bone deposition)
Type II collagen is replaced by type I collagen.
Followed by mineralization of the collagen.

(osteoid)

Enchondral ossification- formation of lamellar

bone over hyaline cartilage
Bone substitution- formation of lamellar bone

over woven bone.


REMODELLING

Recycling of minerals (calcium and

Osteoclast with their cutting cones

phosphate)

Conversion of primary lamel ar bone

Resorbs the bone and form howship lacunae

Secondary lamel ar bone

According to the functional load and

May last upto 7 years

stress(wolff's law)

Osteoblast then grows and lay down the

lamel ar bone

FACTORS AFFECTING REMODELLING

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

deposition on concave side and bone

resorption at convex side). So any

deformity near the physis have more

chances of remodeling

? Presence of deformity near the

particular physis. Remodeling is more

when present near proximal humerus

than distal humerus.


FACTORS AFFECTING REMODELLING

? Fracture location- fracture near

the metaphysis remodels faster.

? Age of the patient

? Pathological bone

FACTORS AFFECTING FRACTURE REPAIR

Method of treatment

Affect of age and site of fracture

Absolute stability, rigid fixation, low strain

environment

Fracture heals faster in children by 1.5 to 2 times

than in old age

Primary fracture repair
FACTORS AFFECTING FRACTURE REPAIR

Smoking

Radiation

Oste oblastic

osteoporosis

can cause

activity

inhibits

1. Osteoradionecrosis

induces

2. Fractures

smoking

3. Bone growth changes

inhibits

Inhibits

4. Radiation induced cancers

Estrogen

activity

Antioxidant

properties of

vitamin C and

E

BONE GRAFT AND BONE GRAFT SUBSTITUTE

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

Provide
Latticework for ingrowth of host bone- osteoconductive

Supply living osteogenic cells- osteogenic property

Growth factors to induce bone formation- osteoinduction

BONE GRAFT AND BONE GRAFT SUBSTITUTE

Types of graft-

1. Cancellous graft

2. Cortical graft

3. Cortico- cancellous graft

4. Auto graft

5. Syngraft

6. Allograft

7. Xenograft

8. Synthetic graft
BONE GRAFT AND BONE GRAFT SUBSTITUTE

Sites of obtaining cancellous bone auto graft
1. Iliac crest
2. Proximal tibia
3. Trochanteric region of femur
4. Distal condyle of femur
5. Olecranon process of ulna
6. Distal radius styloid process.

BONE GRAFT AND BONE GRAFT SUBSTITUTE

Sites for obtaining cortical bone auto graft
1. Fibula
2. Tibia proximal half
BONE GRAFT AND BONE GRAFT SUBSTITUTE

Types of allograft-
1. Fresh
2. Fresh frozen
3. Freeze dried (lyophilized)
4. Osteochondral allograft
5. Large composite graft

This post was last modified on 07 April 2022