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Make me 10 marks answer for fracture healing point by point using this reference

Here is a structured 10-marks answer on Fracture Healing based on Essential Orthopaedics (Frost, 1989):

FRACTURE HEALING

Definition: The healing of fractures is in many ways similar to the healing of soft tissue wounds, except that soft tissue heals with fibrous tissue and the end result of bone healing is mineralised mesenchymal tissue (i.e., bone).

STAGES IN FRACTURE HEALING OF CORTICAL BONE (Frost, 1989)

1. Stage of Haematoma (< 7 days)

  • When a bone is fractured, blood leaks out through torn vessels in the bone and forms a haematoma between and around the fracture.
  • The periosteum and local soft tissues are stripped from the fracture ends, causing ischaemic necrosis of the fracture ends over a variable length (usually only a few millimetres).
  • Deprived of blood supply, some osteocytes die; others are sensitised and differentiate into daughter cells that later contribute to healing.

2. Stage of Granulation Tissue (up to 2-3 weeks)

  • Sensitised precursor (daughter) cells produce cells that differentiate and organise to provide blood vessels, fibroblasts, osteoblasts, etc.
  • Collectively they form a soft granulation tissue in the space between the fracture fragments.
  • This tissue provides soft tissue anchorage to the fracture, without any structural rigidity.
  • The blood clot gives rise to a loose fibrous mesh serving as a framework for ingrowth of fibroblasts and new capillaries.
  • The clot is eventually removed by macrophages, giant cells, and other cells arising in the granulation tissue.
  • The fracture is still mobile at this stage.

3. Stage of Callus (4-12 weeks)

  • Granulation tissue differentiates further and creates osteoblasts.
  • These cells lay down an intercellular matrix which is impregnated with calcium salts, forming the callus (also called woven bone).
  • Callus is the first sign of union visible on X-ray, usually 3 weeks after the fracture.
  • The bridge of woven bone imparts good strength to the fracture.
  • The fracture is now clinically united - no more mobile.
  • Callus formation is slower in adults than in children, and in cortical bones compared to cancellous bones.

4. Stage of Remodelling (formerly Consolidation) (1-2 years)

  • Woven bone is replaced by mature bone with a typical lamellar structure.
  • This process is multicellular unit based - a pocket of callus is replaced by a pocket of lamellar bone.
  • It is a slow process, taking anywhere from one to four years.
  • The outline of the callus becomes dense and sharply defined.

5. Stage of Modelling (formerly Remodelling) (Many years)

  • The bone is gradually strengthened.
  • Shapening of cortices occurs at the endosteal and periosteal surfaces.
  • The stimulus comes from local bone strains (weight-bearing stresses and muscle forces).
  • The fracture site eventually becomes indistinguishable from the parent bone.
  • More conspicuous in children with angulated fractures; occurs to a very limited extent in adults.

PRIMARY vs. SECONDARY BONE HEALING

FeaturePrimary HealingSecondary Healing
HaematomaDisturbed (operative)Not disturbed (non-operative)
CallusNo callus formedCallus forms
X-ray evaluationDifficultEvaluable
ExamplesRigid fixation (plates)Intramedullary nails, casts

FACTORS AFFECTING FRACTURE HEALING

  1. Age of patient - Children heal faster; callus visible as early as 2 weeks. Failure of union is uncommon in children.
  2. Type of bone - Flat and cancellous bones unite faster than tubular and cortical bones.
  3. Pattern of fracture - Spiral > oblique > transverse in healing speed. Comminuted fractures heal slower.
  4. Disturbed pathoanatomy - Soft tissue interposition or ischaemic fracture ends hinder healing.
  5. Type of reduction - Good apposition speeds union; at least half the fracture surface must be in contact in adults.
  6. Immobilisation - Some fractures need strict immobilisation; without it, they may not heal.
  7. Open fractures - Often go into delayed union or non-union.
  8. Compression at fracture site - Enhances rate of union; in cortical bones, it enhances rigidity and may lead to primary bone healing.

HIGH-YIELD EXAM POINTS

  • Pathognomonic sign of fresh/traumatic fracture: Crepitus
  • Most common cause of non-union: Inadequate immobilisation
  • Markers of bone formation: Serum bone-specific alkaline phosphatase, serum osteocalcin, serum peptide of type 1 collagen
  • Markers of bone resorption: Urine and serum crosslinked 'N' and 'C' telopeptide, urine total free deoxypyridinoline
  • Rate of mineralisation determined by: Labelled tetracycline
Reference: Essential Orthopaedics - Chapter 2, Anatomy of Bone and Fracture Healing (Frost, 1989)

Please make the stages of fracture healing a little short but keep main point in each stage

FRACTURE HEALING

(Essential Orthopaedics - Frost, 1989)
Definition: Fracture healing is similar to soft tissue wound healing, except the end result is mineralised mesenchymal tissue (bone), not fibrous tissue.

STAGES IN FRACTURE HEALING OF CORTICAL BONE

1. Stage of Haematoma (< 7 days)

  • Blood leaks from torn vessels forming a haematoma around the fracture site.
  • Periosteum is stripped → ischaemic necrosis of fracture ends.
  • Surviving osteocytes are sensitised → differentiate into daughter cells for later healing.

2. Stage of Granulation Tissue (up to 2-3 weeks)

  • Daughter cells differentiate into blood vessels, fibroblasts, and osteoblasts.
  • Form soft granulation tissue between fragments - no structural rigidity yet.
  • Fracture is still mobile at this stage.

3. Stage of Callus (4-12 weeks)

  • Granulation tissue → osteoblasts → lay down matrix → impregnated with calcium salts = callus (woven bone).
  • First sign visible on X-ray (~3 weeks).
  • Fracture becomes clinically united - no longer mobile.

4. Stage of Remodelling (1-2 years)

  • Woven bone replaced by mature lamellar bone (multicellular unit based process).
  • Callus outline becomes dense and sharply defined.

5. Stage of Modelling (Many years)

  • Cortices shaped at endosteal and periosteal surfaces.
  • Driven by weight-bearing stresses and muscle forces.
  • Fracture site becomes indistinguishable from parent bone.

PRIMARY vs. SECONDARY BONE HEALING

FeaturePrimarySecondary
HaematomaDisturbedIntact
CallusAbsentPresent
ExampleRigid plate fixationCast/IM nail

FACTORS AFFECTING FRACTURE HEALING

  1. Age - Children heal faster (callus visible at 2 weeks); non-union rare in children.
  2. Type of bone - Cancellous > cortical in healing speed.
  3. Pattern of fracture - Spiral > oblique > transverse; comminuted = slowest.
  4. Disturbed pathoanatomy - Soft tissue interposition or ischaemic ends delay healing.
  5. Type of reduction - Good apposition (≥ half surface contact) speeds union.
  6. Immobilisation - Inadequate immobilisation = most common cause of non-union.
  7. Open fractures - Prone to delayed union and non-union.
  8. Compression at fracture site - Enhances union; may lead to primary bone healing.

HIGH-YIELD EXAM POINTS

  • Pathognomonic sign of fresh fracture → Crepitus
  • Most common cause of non-union → Inadequate immobilisation
  • Markers of bone formation → Serum bone-specific ALP, osteocalcin, type 1 collagen peptide
  • Markers of bone resorption → Crosslinked N & C telopeptide, deoxypyridinoline
  • Rate of mineralisation → Labelled tetracycline
Reference: Essential Orthopaedics, Ch. 2 (Frost, 1989)
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