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 [Ca 10 (PO 4 ) 6 (OH) 2 ] Osteocalsiyun Phosfate
Principles of Fracture Healing Types of Fracture Healing 1.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 èHematoma Formation 1-2 Days èInflammation 2-7 Days èSoft Callus Formation 1-3 Weeks èHard Callus Formation 3-6 Weeks èRemodelling Phase >8. Weeks
Principles of Fracture Healing Hematoma Formation Hematoma forms in medullary canal and surrounding soft tissue in first 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 Periost Devitalized marrow Endosteum Hematoma Dead osteocytes/empty lacunae WBC Angiogenesis Granulation tissue
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 Granulation tissue Fibrous tissue Fibrocartilage
Principles of Fracture Healing Hard Callus Formation Intramembranous ossification bone from fibrous tissue Endochondral ossification bone from cartilage
Principles of Fracture Healing Hard Callus Formation Fibrous tissue Intramembranous ossification Fibrocartilage Endochondral ossification
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 fracture healing 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