Book reading

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Book reading

• Rockwood Ch.8
• Bone and joint healing

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(No Transcript)
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FIGURE 8-1 Initial events following fracture of a
long bone diaphysis. A. Drawing showing that the
periosteum is torn opposite the point of impact,
and may remain intact on the other side. A
hematoma accumulates beneath the periosteum and
between the fracture ends. There is necrotic
marrow and cortical bone close to the fracture
line. B. A photomicrograph of a fractured rat
femur three days after injury showing the
proliferation of the periosteal repair tissue.
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FIGURE 8-2 Early repair of a diaphyseal fracture
of a long bone. A. Drawing showing organization
of the hematoma, early woven bone formation in
the subperiosteal regions, and cartilage
formation in other areas. Periosteal cells
contribute to healing this type of injury. If the
fracture is rigidly immobilized or if it occurs
primarily through cancellous bone and the
cancellous surfaces lie in close apposition,
there will be little evidence of fracture callus.
B. Photomicrograph of a fractured rat femur nine
days after injury showing cartilage and bone
formation in the subperiosteal regions.
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FIGURE 8-3 Progressive fracture healing by
fracture callus. A. Drawing showing woven or
fiber bone bridging the fracture gap and uniting
the fracture fragments. Cartilage remains in the
regions most distant from ingrowing capillary
buds. In many instances, the capillaries are
surrounded by new bone. Vessels revascularize the
cortical bone at the fracture site. B.
Photomicrograph of a fractured rat femur 21 days
after injury showing fracture callus united the
fracture fragments
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FIGURE 8-4 Light micrograph showing healing of a
diaphyseal fracture under conditions of loading
and motion. This femur fracture occurred in a pig
that continued to use the limb for three weeks.
Even though the fracture was not stabilized, it
is healing. A large fracture callus consisting
primarily of woven bone surrounds and unites the
two fracture fragments. As the callus matures it
progressively stabilizes the fracture. Notice
that the fracture callus contains areas of
mineralized mineralized and unmineralized
cartilage.
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FIGURE 8-5 A schematic representation of the
changing composition and mass of fracture callus.
Collagen formation precedes significant
accumulation of mineral. After an initial rise,
proteoglycan concentration falls gradually as
fracture healing progresses. The total mass of
the fracture callus increases during repair and
then decreases during remodeling
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• clinical union--stable and pain-free
• radiographic union--trabeculae or cortical bone
  crossing the fracture site

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fracture stability

• Stage I A healing bone subjected to torsional
  testing fails through the original fracture site
  with a low-stiffness pattern.
• Stage II The bone still fails through the
  fracture site, but the characteristics of failure
  indicate a high-stiffness, hard-tissue pattern.
• Stage III The bone fails partly through the
  original fracture site and partly through the
  previously intact bone with a high-stiffness,
  hard-tissue pattern.
• Stage IV Failure does not occur through the
  fracture site, indicating that new tissue at the
  fracture site duplicates the mechanical
  properties of the uninjured tissue.

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Failure of Fracture Healing

• Watson-Jones described a condition he called slow
  union--no undue separation of the fragments, no
  cavitation of the surfaces, no calcification, and
  no sclerosis
• Due to severity of the injury, poor blood supply,
  the age and nutritional status of the patient

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Nonunion

• hypertrophic nonunion
• atrophic nonunion
• pseudarthrosis
• fibrous union

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FIGURE 8-6 Hypertrophic delayed union of a distal
tibial fracture 5 months after injury. Note the
abundant callus but incomplete bridging of the
fracture gap
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FIGURE 8-7 Atrophic nonunion of a humeral shaft
fracture 18 months after fracture. Note the
absence of callus.