Principles of Fracture Healing

Faik Altıntas M.D.

Orthopaedic and Traumatology

Principles of Fracture Healing Diaphysis Shaft of a long bone Epiphysis Ends of the bone Metaphysis Area between the diaphysis and epiphyses Hyaline cartilage Found at the ends of the bone Periostium Membrane covering the bone Marrow cavity Space in the diaphysis Endosteum Lining of the medullary cavity

Principles of Fracture Healing

Principles of Fracture Healing

Bone ConsistsOrganic component (%40)

CollagenProteoglicansMatrix proteins

İnorganic component (%60)Calsiyum hidroksiapatite [Ca10(PO4)6(OH)2]

Osteocalsiyun Phosfate

Principles of Fracture Healing

Types of Fracture Healing1. Primary Healing

2. Secondary Healing

3. Distraction Osteogenesis

Principles of Fracture Healing

Primary fracture healing Involves direct attempt by the cortex to

reestablish itself Occurs only with anatomic reduction & rigid

fixation Gaps in reduction heal by vessel ingrowth-

mesenchymal cells- osteoblasts-osteoclast cutting cones

Direct contact areas heal by cutting cones allowing passage of vessels

Principles of Fracture Healing

Secondary fracture healing Response of periosteum/ external soft tissues Recapitulation of embryonic intramembranous

ossification and endochondral bone formation Intramembraneous= peripheral to fracture Endochondral= adjacent to fracture Motion enhances periosteal response External soft tissue forms bridging calus

(endochondral)

Principles of Fracture Healing

Stages of Healing Hematoma Formation 1-2 Days Inflammation 2-7 Days Soft Callus Formation 1-3 Weeks Hard Callus Formation 3-6 Weeks Remodelling Phase >8. Weeks

Principles of Fracture Healing

Hematoma Formation Hematoma forms in

medullary canal and surrounding soft tissue in first 24-48 hours

Principles of Fracture HealingInflammation Hematoma in fracture site brings hematopoietic cells

secreting growth factor Growth factors

Insulin-like growth factor (IGF-1) Transforming growth factor (TGF) Vascular endothelial growth factor (VEGF) Fibroblast growth factor (FGF)

Fibroblasts, osteoprogenitor cells produce granulation tissue around fracture ends

Osteoblasts proliferate By 1st-2nd week, abundant cartilage over fracture site

ready for calcification (occurs identical to growth plate)

Principles of Fracture Healing

InflammationPeriost

Devitalized marrowEndosteum

Hematoma

Dead osteocytes/empty lacunae

WBC

AngiogenesisGranulationtissue

Principles of Fracture HealingSoft Callus ( Fibrous Callus) Formation Fibrous tissue forms at periphery where blood

supply is abundant Fibrocartilage forms at center where blood

supply is limited Increased instability results in increased callus

size Tissues bridge fracture and decrease

interfragmentary strain

Principles of Fracture HealingSoft Callus ( Fibrous Callus) Formation

Granulation tissue

Fibrous tissue

Fibrocartilage

Principles of Fracture HealingHard Callus Formation Intramembranous

ossification bone from fibrous tissue

Endochondral ossification bone from cartilage

Principles of Fracture HealingHard Callus Formation

Fibrous tissueIntramembranousossification

Fibrocartilage Endochondralossification

Principles of Fracture Healing

Remodelling Phase Begins in middle of repair phase, continues until fx

clinically healed Osteoclastic tunneling (cutting cones) in concert

with osteoblast deposition Can continue up to 7 years Remodeling based on stresses (Wolff’s law)

Bone formed in response to mechanical load

Principles of Fracture Healing

Principles of Fracture Healing

Principles of Fracture Healing

Principles of Fracture HealingDistraction Osteogenesis Gradual traction applied to cortical osteotomy Bone forms under the law of tension stress

Wolff’s Law occurs even with tension Typically intramembranous ossification Used in limb lengthening Treatment of limb deformities Transportation of cortical bone

Principles of Fracture Healing

Conditions that interfere with fracture healingHigh energy traumas brings soft tissue problems that lead

non uniounPoor blood supply to the fractured area; could lead to

avascular or aseptic necrosis Poor immobilization of fracture site may cause

misalignment, nonunion or deformity Infection – more common with open fractures Cortisone= negative effect, decreased callus formation