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