Thrall Chapter 19 fracture healing and complications Flashcards
(20 cards)
1) Which of the statements below are true of intramembranous ossification (more than one may be correct)?
a) It begins with mesenchymal cells that differentiate into osteoblasts that form a matrix, which then becomes calcified
b) It progresses by the formation of a cartilage model derived from the mesenchyma that is then replaced by bone
c) It occurs at the epiphyses of bones
d) It occurs primarily in the bones of the calvarium and mandible
a,d
2) Which region of endochondral ossification is the weakest zone and the most common location for physeal fractures?
a) The resting zone containing immature cells of the epiphyseal side of the physis
b) The cell growth and proliferation zone
c) The cell hypertrophy zone
d) The provisional calcification or ossification zone
c- middle layer
3) Which statements are true regarding indirect (secondary) bone healing?
a) It involved endochondral ossification only
b) It occurs in fractures where there is no movement between the fragments
c) The first step is characterized by haematoma formation and inflammation
d) Undifferentiated mesenchymal cells from soft tissues and the periosteum are recruited to help with healing
c,d
4) What is the incidence of non-union fracture in dogs?
a) 0-6%
b) 6-10%
c) 10-14%
d) 14-18%
a
5) In the image below what is indicated by the arrow?
a) A neoplastic process
b) Osteomyelitis
c) Sequestrum formation
d) Callus formation due to periosteal stripping at the time of injury
d
6) Which of the following fractures more commonly occurs in cuboidal bones?
a) Slab
b) Avulsion
c) Spiral
d) Transverse
a
7) Which of the following factors is the most common cause of delayed union in veterinary patients?
a) Inadequate nutrition
b) Excessive rigidity of repair
c) Excessive motion at the fracture site
d) Endocrinopathies
c
8) Which is the most common site for growth plate closure after a salter harris type fracture?
a) Proximal ulnar physis
b) Distal ulnar physis
c) Distal femoral physis
d) Proximal radial physis
b
9) Which zone of endochondral ossification is closest to the epiphysis?
a) Cell growth and proliferation
b) Resting
c) Ossification
d) Preliminary calcification
e) Cell hypertrophy
b (resting, proliferation, hypertrophy, calcification, ossification)
10) For distraction osteogenesis, intentional mechanical gradual widening is used to lengthen the bone, how much is the gap widened per day?
a) 4mm
b) 3mm
c) 2mm
d) 1mm
d
11) From the primary centre of ossification of a long bone, what type of ossification is occurring in the initial stage of bone growth?
a) Distraction
b) Endochondral
c) Intramembranous
d) Secondary
c
12) What is the incidence of non-union fracture in cats?
a) 0-5%
b) 0.85-7%
c) 0.85- 4.3%
d) 4-7.56%
c
13) Which of the below is the definition for oligotrophic nonunion?
a) Moderate callus formation that is less than the amount seen with hypertrophic non- union.
b) Little or no callus, with bridging of the fracture fragments with fibrous tissue. Scintigraphy may be needed to assess blood supply to the fracture gap
c) A radiolucent fracture gap with no evidence of callus and rounded sclerotic bone edges.
B, A is moderate hypertrophic nonunion, C is dystrophic non-union
what is the effect of parathyroid hormone on bone?
a) stimulate osteocyte activity causing increased osteoid production
b) stimulates osteoblast activity, causing release of enzymes and acids, leading to bone resorption
c) stimulates osteoclast activity leading to bone resorption
d) activates osteoclasts, leading to osteoid production
C
Osteoblasts synthesize the osteoid bone matrix and become osteocytes following mineralization of the osteoid. Osteoclasts are larger cells that reside on the surface of the mineralized matrix and remove both mineral and matrix by secretion of acids and enzymes.
Parathyroid hormone increases serum calcium by stimulating osteoclastic bone resorption
what is the definition of intramembraneous ossification?
synthesis of bone directly from osteogenic mesenchymal cells without a cartilage precursor
Most flat bones such as the skull and mandibles are developed this way and intramembranous ossification plays a role in increasing the width of long bones
what is the definition of endochondral ossification?
endochondral ossification, a cartilage model derived from the mesenchyme is formed and subsequently mineralized to form bone
mesenchymal cells are stimulated to differentiate into chondrocytes rather than osteoblasts. Endochondral ossification is the primary mechanism to form the appendicular and portions of the axial skeleton such as the vertebrae, ribs, sternebral, and flat bones of the pelvis
what features have to be present for direct bone healing?
when the gap between fracture fragments is less than 0.01mm and there is less than 2% strain or motion between the fragments.
In direct healing, lamellar bone is formed directly between the two fragments where osteoclasts remove dead bone and osteoblasts follow immediately behind and form new bone. Radiographically, direct bone healing is characterized by slow disappearance of a fracture gap without callus formation. This type of healing is most commonly seen after a corrective osteotomy with reapposition that results in a minimal gap
what are the steps of indirect fracture healing?
haematoma- granulation- fibrous tissue- bone
too much instability (>5%) is detrimental to fracture healing and may lead to delayed union, malunion, nonunion, or pseudarthrosis formation
which is recurvatum and which is antercurvatum
left recurvatum, right antercurvatum
which physis has closed
distal radial physis
opposite effect if distal ulna physis
