fracture healing..pptx---https://m.youtube.com/@jalalmohiuddin9497

https://m.youtube.com/@jalalmohiuddin9497

for Undergraduates MBBS
easy and simple presentation
exam oriented

1. Bone formation in Embryo: Enchondral ossification: Mesenchymal tissue---- Cartilage(Chondrocytes)---bone(osteoblast). Intra- memberanous ossification Mesenchymal tissue---- bone(osteoblast). Woven bone lamellar bone Compact bone -outer layer of long bones, is dense and solid, and provides strength and protection. .. Spongy bone--- inner layer of flat and irregular bones, porous structure, and contributes to shock absorption and reducing weight…

2. Fracture healing : complex and sequential set of events to restore injured bone to pre-fracture condition….. Stem cells : stem cells are crucial to the fracture repair process. periosteum (cambium layer) endosteum . Modes of bone healing : primary bone healing.   intramembranous healing occurs via  Haversian remodeling. occurs with absolute stability constructs. Locking plates Does not involve formation of fracture callus. • Osteoblasts originate from endothelial and perivascular cells.  Plating a fracture is similar to suturing a laceration . approximate the ends of the disrupted tissue, compress them and hold them together tightly.

3. secondary bone healing : involves responses in the periosteum and external soft tissues. endochondral healing  . occurs with non-rigid fixation . fracture braces, external fixation, bridge plating, intramedullary nailing, etc Bone breaks- ---  Hematoma (blood clot) forms at the site of the break with migration of cells (inflammation )---  a primary callus composed of granulation tissue, fibroblasts, and new blood vessels forms from the hematoma--  callus cells produce cartilage , which is eventually mineralized to form woven ( disorganized bone )---  the woven bone remodels into normal bone/lamellar bone(compac t bone).

4. 3 major phases with sub divisions: A . Reactive Phase: • i . Fracture and inflammatory phase. • ii. Stage of hematoma formation. • iii. Granulation tissue formation. B . Reparative Phase: • iv. Cartilage Callus formation. • v. Lamellar bone deposition . C . Remodeling Phase: • vi. Remodeling to original bone contour.

5. Reactive phase: Fracture & inflammatory phase : (1 week) blood cells within the tissues which are adjacent to the injury site. the blood vessels constrict, stopping any further bleeding. ii. Stage of Hematoma formation:   few hours after fracture, extravascular blood cells form a blood clot--  hematoma . Hematoma forms and provides a source of hematopoietic cells capable of secreting growth factors. iii . Granulation Tissue Formation:   Migration of Macrophages , neutrophils, and platelets. Resorbtion of fracture ends. Fibroblast proliferate and form scaffold. release several cytokines . this includes PDGF, TNF-Alpha, TGF-Beta, IL-1,6, 10,12 BMPs , fibroblasts and mesenchymal cells migrate to fracture site and granulation tissue forms around fracture ends.

6. B. REPARATIVE PHASE Cartilage Callus formation : (1 week to 4 weeks) the periosteal cells proximal to the fracture gap and fibroblasts develop into chondroblasts which form hyaline cartilage. The periosteal cells distal to the fracture gap develop into osteoblasts which form woven bone. new mass of heterogenous tissue called Fracture Callus( chondoblastic and osteoblastic tissue) Lamellar bone deposition : (4 weeks to 8 weeks) hyaline cartilage and woven bone is replaced by lamellar bone . Endochondral ossification. Mineralization starts . This new lamellar bone is in the form of trabecular bone which restores bone’s original strength…

7. REMODELLING PHASE: Remodelling to original bone contour ( after 2 months). The remodeling process substitutes the trabecular bone with compact bone. The trabecular bone is first resorbed by osteoclasts, creating a shallow resorption pit known as a " Howship's lacuna". osteoblasts deposit compact bone within the resorption pit. . Eventually , the fracture callus is remodelled .

8. Factors effecting fracture healing: Internal /local factors: blood supply (most important ). bony soft tissue attachments/Injury. mechanical stability/strain . location of injury. degree of bone/soft tissue loss. Fracture pattern (segmental or fractures with butterfly fragments ). Systemic factors: Age Nutrition status—protein/Vitamin D. Smoking CKD/Diabetes/HIV infection Head injury Medication: bisphosphonates NSAIDS steroids Quinolones