LEC 2 fracture healing

• Types of Fractures:

  • Linear: Fracture parallel to the long axis of the bone
  • Transverse: Fracture perpendicular to the long axis of the bone
  • Compound (Open): Bone ends penetrate the skin
  • Simple (Closed): Bone ends do not penetrate the skin
  • Comminuted: Bone fragments into three or more pieces
  • Spiral: Ragged break when bone is excessively twisted
  • Depressed: Broken bone portion pressed inward, typical in skull fractures
  • Compression: Bone is crushed, common in porous bones
  • Epiphyseal: Epiphysis separates from diaphysis along the epiphyseal line
• • Greenstick: Incomplete fracture where one side of the bone breaks and the other side bends, common in children
  • Pathologic: Involving bone weakened by an underlying disease process, such as a tumor
• Complications of Fracture Healing:

  • Delayed Union: Prolonged healing process leading to delayed union of bone fragments
  • Non-union: Failure of the fractured bone to heal, resulting in a persistent gap between bone fragments
  • Malunion: Healing of the bone in a deformed or misaligned position
  • Infection: Introduction of pathogens at the site of the fracture, leading to potential complications
  • Compartment Syndrome: Increased pressure within the muscles, leading to potential nerve and tissue damage
• • Avascular Necrosis: Loss of blood supply to the fractured bone, resulting in bone tissue death
• The process of healing in fractures:

  • Reactive Phase:
  • Blood vessels at the site of the fracture constrict to minimize bleeding
  • Inflammatory cells, such as neutrophils and macrophages, remove debris and bacteria from the fracture site
  • The release of inflammatory mediators initiates the formation of a hematoma at the fracture site
  • Repair Phase:
  • Osteogenic cells differentiate into chondroblasts and osteoblasts to form a soft callus made of fibrocartilage
  • Osteoblasts produce new bone matrix, leading to the formation of a hard callus composed of woven bone
• • Blood vessels grow into the fracture site, providing nutrients and oxygen for bone formation
  • Remodeling Phase:
  • Osteoclasts resorb the excess bony tissue, reshaping the bone to its original form
  • Compact bone is laid down along lines of mechanical stress, restoring the strength of the bone
• Factors which affect healing of fractures:

  • Age: Younger individuals generally have better healing capacity due to higher bone turnover and growth factors
  • Nutrition: Adequate intake of protein, vitamins (especially vitamin C and D), and minerals (calcium, phosphorus) is essential for bone healing
  • Blood Supply: Proper blood circulation to the fracture site is crucial for delivering nutrients and oxygen necessary for healing
  • Smoking: Tobacco use can impair bone healing by reducing blood flow and oxygen delivery to the fracture site
• • Local Anatomic Factors: Factors such as the extent of soft tissue injury, interruption of local blood supply, and interposition of soft tissue at the fracture site can influence healing
• • Medications: Certain medications, such as corticosteroids and some anti-inflammatory drugs, can interfere with bone healing
  • Systemic Diseases: Conditions like diabetes and osteoporosis can negatively impact bone healing
  • Infection: Presence of infection at the fracture site can significantly impede the healing process
  • Mechanical Stability: Proper immobilization and alignment of the fractured bone are essential for optimal healing
  • Soft Tissue Damage: Extensive soft tissue damage around the fracture can impede the healing process
• The complications of fracture healing:

  • Deformity:
  • Improper alignment or stabilization of the fractured bone can lead to deformities during the healing process
  • Delayed union:
  • Prolonged healing time beyond the expected duration for a particular type of fracture
  • Non-union:
  • Failure of the fractured bone to heal, resulting in persistent mobility and pain at the fracture site
  • Pseudoarthrosis:
  • Formation of a false joint at the fracture site due to the persistence of nonunion, leading to abnormal movement and pain
  • Infection of fracture site in open fractures:
• • Open fractures are at risk of infection, which can significantly impede the healing process and lead to further complications
  • Inadequate immobilization:
  • Insufficient stabilization or immobilization of the fracture can prevent normal callus formation and impede proper healing
• The remodelling of bone:

  • Constant turnover:
  • The adult skeleton is constantly undergoing a tightly regulated process known as remodeling
  • Approximately 10% of the skeleton is replaced annually through this process
  • Microscopic process:
  • Remodeling takes place at a microscopic locus known as the bone/basic multicellular unit (BMU)
  • The BMU consists of a unit of coupled osteoblast and osteoclast activity on the bone surface
  • Sequence of events:
• • An orderly sequence of activities occurs at the BMU, including osteoclast attachment, resorption, osteoblast attachment, proliferation, and matrix synthesis
  • Repair and adaptation:
  • Remodeling can repair microdamage in bones and change the shape of bones in response to structural and mechanical demands
  • Restoration of bone quality:
  • Remodeling helps maintain bone strength and integrity by replacing old or damaged bone with new, healthy bone tissue