Bone Biomechanics and Fx bio Flashcards
Which of the following is not correct?
A With pure bending the fracture occurs in the center of the bone
B With cantilever bending the fracture occurs at the point of fixation
C With 3 point bending the fracture occurs at the site of load application
A false (false, anywhere along the bone)
Match the fracture pattern with the force applied to the bone
Oblique, Transverse, Mildly comminuted (butterfly fragment), Spiral
i. Bending
ii. Torsion
iii. Compression
iv. Bending and compression
Oblique (iii)
Transverse (i)
Mildly comminuted (butterfly fragment) (iv)
Spiral (ii)
Which of the following is FALSE regarding bone healing?
A Most fractures will heal without surgical intervention or even external coaptation
B Fracture resorption as part of the initial bone healing increases the fracture gap and decreases interfragmentary strain
C Granulation tissue provides stability in the first 3-4 days of healing
D Small fracture gaps hasten healing
D (false, if the strain is too high)
Which is true?
A. With an interfragmentary gap of approximately 1 mm, cartilage forms in the fracture gap.
B The lamellar bone is initially oriented transverse to the long axis of the bone.
C Around the second week of healing, Haversian remodeling occurs and osteons begin to cross the gap, resorbing the new lamellar bone and replacing it with longitudinally oriented osteons.
D The only physical requirement for primary bone healing is a less than 2% interfragmentary strain environment.
B correct
A (lamellar bone)
C third week of healing for remodeling
D (2 requirements - also need a less than approximately 1 mm interfragmentary gap.)
Which is true?
A. With distraction osteogenesis, the regenerate bone is formed via endochondral ossification.
B. A central radiolucent zone within the gap, called the fibrous interzone, is composed of transverse oriented collagen.
C. On one side of this zone is an area of vascular ingrowth where osteoblasts deposit osteoid along the collagen bundles.
D. Throughout the distraction period, the fibrous interzone remains radiolucent and of consistent width, while the mineralized zones on either side lengthen.
D correct
A (intramembranous)
B. Fibrous interzone = (longitudinal) oriented collagen
C. (on both sides)
True/false: Biologic tissues are linear, viscoelastic, homogenous and anisotropic materials
False = NONlinear, viscoelastic, INhomogenous, anisotropic material
True/false: strain is defined pointwise, can be expressed in many ways, and there are limitations to the conditions under which the most common forms of strain should be applied.
True
Which statement is true?
A. Vertical impulse is a force exerted on the ground by the body in contact with it
B. Cauchy stress = engineering strain = when a force is applied, the constituent elements in the body interact and distribute the applied force throughout the body
C. Resilience = area under the entire stress-strain curve
D. Ultimate strength point = transition from elastic to plastic behavior
B correct
A. Vertical impulse= change in the vertical momentum
GRF is a force exerted by the ground ON the body in contact with it
C. Resilience = area under the stress-strain curve up to the proportional limit
Toughness =area under the entire stress-strain curve
D. Ultimate strength point = sample loses integrity and can no longer bear an increasing load
Yield point=transition from elastic to plastic behavior
True/false: Young’s modulus is the slope of the stress/strain curve and is a measure of the stiffness, a product of linear elastic theory and should be only used on specific materials
True: linear, elastic, homgenous and isotropic materials
Which statement is true?
A. Viscoelastic materials are not sensitive to conditioning
B. In the toe region, relatively low strains are achieved at high stress levels
C. Creep-recovery is when a initial spike of stress then decreases as material relaxes
D. Apparent stiffness often varies with strain rate
D. correct
A. Very sensitive
B. toe = high strain and very low stress levels
C. Stress relaxation = spike and relax
Creep recovery = slow adaptation of material to step strain response to an equilibrium
Which of the following is true?
A. Plexiform bone is composed of nonlamellar and primary lamellar bone
B. The Volkman’s line is where bone formation began
C. Only cancellous bone has lamellar bone
D. The endocortical envelope contains the cambium
A is true
B. Volkmann canals have vessels that link Haversian vessels to bone marrow vasculature. Cement line
C.BOTHcortical and cancellous bone have lamellar bone
D. Periosteal envelope has cambium; endocortical envelope has osteoprogenitor “lining cells”
Which is true?
A. PPARy induces osteogenic differentiation and RUNX2 block adipogenic differentiation
B. Fibrocartilage is replaced by bone in endochondral ossification
C. Combo of hypoxia, matrix calcification and VEGF results in recruitment of primary blood vessels to penetrate bone collar
D. Resorptive remodeling is due to osteoblasts
C is correct
A. RUNX2= osteogenic gene and Wnt ligand inhibits PPARy to block adip. (intramembranous ossification)
B. hyaline cartilage
D. Osteoclasts (formation modeling= osteoblasts)
Name the 5 zones of epiphyseal plate from epiphysis towards diaphysis
- Resting zone
- Proliferative zone (type II collagen)
- Hypertrophic zone (type X collagen, WEAK)
- Zone of calcification
- Zone of ossification
which is true?
A. Butterfly fragment forms on the tension side of bending
B. Cancellous bone can withstand a higher strain at 55% compared to 10% cortical
C. Fibrocartilage can only accommodate 5% deformation
D. Contact healing and gap healing are types of primary bone healing
D. is true
A. compression side
B. 75% compared to 2%
C. 10-15%
List the 5 steps of secondary bone healing
- Inflammation
- Intramembranous Ossification
- Soft callus formation (Chondrogenesis)
- Hard callus formation (endochondral ossification)
- Bone remodeling
