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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
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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 • Bone Consists • Organic component (%40) • Collagen • Proteoglicans • Matrix proteins • İnorganic component (%60) • Calsiyum hidroksiapatite [Ca10(PO4)6(OH)2] • Osteocalsiyun Phosfate
Principles of Fracture Healing Types of Fracture Healing • Primary Healing • Secondary Healing • 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 Healing Inflammation • 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 Inflammation Hematoma Periost Dead osteocytes/empty lacunae WBC Granulation tissue Angiogenesis Devitalized marrow Endosteum
Principles of Fracture Healing Soft 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 Healing Soft Callus ( Fibrous Callus) Formation Fibrous tissue Fibrocartilage Granulation tissue
Principles of Fracture Healing Hard Callus Formation • Intramembranous ossification • bone from fibrous tissue • Endochondral ossification • bone from cartilage
Principles of Fracture Healing Intramembranous ossification Fibrous tissue Hard Callus Formation Endochondral ossification Fibrocartilage
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 Distraction 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 fracturehealing • High energy traumas brings soft tissue problems that lead non unioun • Poor 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