Pathphysiology of fracture healing and repair

Pathophysiology of Fracture Healing and Repair

1. PATHOPHYSIOLOGY OF FRACTURE HEALING AND REPAIR

2. INTRODUCTION Fracture is a break in the structural continuity of bone or periosteum. The healing of fracture is in many ways similiar to the healing in soft tissue wounds except that the end result is mineralised mesenchymal tissue i.e. BONE. Fracture healing starts as soon as bone breaks and continues modelling for many years.

3. The essential event in fracture healing is the creation of a bony bridge between the two fragments which can be readily built upon and modified to suit the particular functional demands .

4. Components of BONE Formation Cortex Periosteum Bone marrow Soft tissue

5. Type of BONE formed OSTEOCHONDRAL INTRAMEMBERANOUS OSSIFICATION OPPOSITIONAL NEW BONE FORMATION OSTEONAL MIGRATION ( Creeping Substitution)

6. FACTORS EFFECTING The TYPE , AMOUNT and LOCATION of bone formed depends upon----- FRACTURE TYPE GAP CONDITION FIXATION RIGIDITY LOADING BIOLOGICAL ENVIRONMENT

7. FRACTURE HEALING TYPES Fracture healing is divided according to bone-- 1. Cortical bone of the shaft. 2. Cancellous bone of the metaphyseal region of the long bones and the small bones.

8. STAGES OF FRACTURE HEALING TISSUE DESTRUCTION AND HAEMATOMA FORMATION INFLAMATION AND CELLULAR PROLIFERATION STAGE OF CALLUS FORMATION STAGE OF COSOLIDATION STAGE OF REMODELLING

9. Tissue destruction and Hematoma formation

10. INFLAMATION AND CELLULAR PROLIFERATION Within 8 hours inflammatory reaction starts. Proliferation and Differentiation of mesenchymal stem cells. Secretion of TGF-B , PDGF and various BMP factors.

11. Callus Formation Fibrocartilaginouscallus forms Granulationtissue (soft callus) forms a few days after the fracture Capillaries grow into the tissue and phagocytic cells begin cleaning debris

12. Callus Formation Theory OSTEOPROGENITOR CELL present in all ENDOSTEAL and SUBPERIOSTEAL surface give rise to CALLUS. CALLUS arises from NON-SPECIALISED CONNECTIVE TISSUE CELLS in the region of fracture which are induced into conversion to OSTEOBLASTS.

13. STAGE OF CONSOLIDATION New bone trabeculae appear in the fibrocartilaginous callus –  Fibrocartilaginous callus converts into a bony (hard) callus –  Bone callus begins 3-4 weeks after injury, and continues until firm union is formed 2-3 months later

14. STAGE OF REMODELLING Excess material on the bone shaft exterior and in the medullary canal is removed  Compact bone is laid down to reconstruct shaft walls

15. Variables Influence Fracture Healing INJURY VARIABLES Open Fractures  Impeding or preventing formation # Hematoma  Delaying formation repair tissue  Risk of infection

16. INJURY VARIABLES Intra articular fractures If the alignment & congruity joint surface is not restored  Delayed healing or non union  Joint stiffness Segmental fractures Soft tissue interposition Damage to the blood supply

17. Patient Variables AGE NUTRTION HEALING PROCESS NEEDS Energy Proteins & carbohydrates

18. Systemic hormones Corticosteroid ( ) Growth hormone Thyroid hormone Calcitonin Rate fracture healing Insulin Anabolic steroids DM Hypervitaminosis D Rate fracture healing Rickets Nicotine Inhibit fracture healing ( Vascularization ?)

19. Tissue Variables Cancellous or cortical bones Bone necrosis Infection

20. Local regulation of bone healing Growth factors Transforming growth factor Bone morphogenetic proteins Fibroblast growth factors Platelet-derived growth factors Insulin-like growth factors   Cytokines Interleukin-1,-4,-6,-11, macrophage and granulocyte/macrophage (GM) colony-stimulating factors (CSFs) and Tumor Necrosis Factor   Prostaglandins/Leukotrienes   Hormones   Growth factor antagonists

21. Refrences Reading : Robbins Basic Pathology, 10 th Edition (2017), By: Kumar, Abbas, Aster WWW.Webpathology.com WWW.fleshandbone.com WWW.studentconsult.com