Bone & joints
Other nonneoplastic
Fracture


Topic Completed: 1 June 2012

Minor changes: 12 January 2021

Copyright: 2003-2021, PathologyOutlines.com, Inc.

PubMed Search: Bone Fracture[title]

Dariusz Borys, M.D.
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Cite this page: Borys D. Fracture. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/bonefracture.html. Accessed January 24th, 2021.
Definition / general
  • Break in continuity of bone, often with severance of blood vessels, periosteum or muscle
  • Complete (bone broken completely) versus incomplete
  • Closed (intact overlying tissue, also called simple) versus compound (fracture site communicates with skin surface)
  • Displaced (ends of bone not aligned)
  • Comminuted (many fragments)
  • Pathologic (due to diseased bone) or traumatic
  • Fractures often due to weakened bone (osteoporosis, tumor, infection) or falls in elderly and children

Types of fractures
  • Spiral configuration through cortex is typical
  • Transverse fractures (like breaking chalk) are associated with Paget disease, osteopetrosis or other severe bone disturbances
  • Stress or insufficiency fractures - see below
  • Avulsion fractures are associated with trauma at ligamentous and tendinous insertions, often in pelvis or distal thigh
Congenital pseudoarthrosis
Fracture callus
Radiology description
  • Stress fractures may resemble tumors with extensive periosteal new bone formation
  • Postmenopausal women may have insufficiency fractures in pelvis resembling metastatic carcinoma

Microscopic (histologic) description
  • Spindle cell proliferation with cartilage and bone
  • May be hypercellular but orderly maturation present
Healing process
  • Hematoma forms between two ends of bone, creates fibrin mesh which seals fracture site
  • Young capillaries enter hematoma
  • Dead bone reabsorption begins at 3 days
  • Periosteal inner layer promotes intramembranous bone growth on each side of fracture, which meets at fracture site to form a primary callus, which anchors ends but doesn’t support weight bearing
  • This is resorbed and replaced by secondary callus, composed of mature lamellar bone
  • New bone is laid down along lines of stress
  • In children, marked bone remodeling occurs, even with gross deformities or shortening of a long bone
  • Open reduction and internal fixation of fractures is usually not needed
  • Movement along fracture line creates lining of synovial cells and pseudoarthritis
  • Soft tissue must be removed and bone stabilized to promote healing
  • Fractures may not heal due to improper immobilization, devascularization of bone fragments, persistent infection or interposition of soft tissue between ends of bone
  • Noncorrosive nails are isolated from bone substance by fibrous tissue; do not elicit foreign body giant cell reaction
Osgood-Schlatter disease
  • Avulsion fractures of tibial tubercle causing fragmentation, in children
  • Most common causes of knee pain in adolescents, pain in children and young athletes usually between the ages of 10 and 15
  • Occurs due to rapid bone growth plus high level of sporting activity; associated with overuse injury
  • Can be quite painful, but usually resolves itself within 12 to 24 months (SportsInjuryClinic.net-Osgood Schlatter Disease)
Primary callus
  • Exuberant cartilage and disorderly membranous bone may resemble osteosarcoma
  • Increased callus is present in unstable areas
Pseudoarthrosis
  • False joint developing after chronic nonunion of a fracture
Stress fractures
Definition / general
  • Also called fatigue or insufficiency fractures
  • Due to physical activity (ballet dancing, long distance running, military training) or metabolic bone disease
  • Usually lower limbs, especially femoral neck in those with metabolic disease, tibial shaft in joggers or dancers, second or third metatarsal bones in military trainees
  • May require serial parallel cuts to find evidence of stress fractures

Gross description
  • White-gray with linear notched zone paralleling subchondral bone end plate

Microscopic (histologic) description
  • Zonal with necrotic, reparative (fracture callus, granulation tissue) and viable tissue

Differential diagnosis
  • Aseptic bone necrosis: younger patients, wedge shaped infarct, total necrosis of bone trabeculae and bone marrow
Subchondral insufficiency fractures
Definition / general
Radiology description
  • Bone marrow edema by MRI

Treatment
  • Immobilization, no NSAIDs

Microscopic (histologic) description
  • Fracture callus and granulation tissue growing along both edges of fracture line
Case reports
Microscopic (histologic) description
  • Varies with type of injury
  • A few days - acute tissue damage and hemorrhage, necrotic bone [empty lacunae, poorly staining bone matrix] at fracture, may be more extensive in patella, femoral neck, carpal scaphoid
  • 1 - 2 weeks - hypercellular, hypervascular tissue, often with brisk mitotic activity, resembles sarcoma but without atypia or atypical mitotic figures; reduced callus in midshaft of tibia or other poorly vascularized areas
  • Callus reduced if rigid internal or external surgical fixation
Microscopic (histologic) images

Contributed by Dr. Mark R. Wick

Fracture callus:
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Atypical cartilage component

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Healing

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