2025
,1- In the context of joint arthroplasty, the alpha-defensin immunoassay test is useful for the detection
of?
1*aseptic loosening.
2*metal corrosion.
3*periprosthetic infection.
4*bone ingrowth.
Correct answer 3
Alpha-defensin is a protein released by activated neutrophils in response to infection. The detection of
alpha-defensin in synovial fluid is highly sensitive and specific as a marker of periprosthetic infection.
Aseptic loosening and the bone ingrowth of prostheses generally are detected radiographically. Metal
corrosion issues—in metal-on-metal prostheses, for example—generally are followed using blood metal
ion levels.
2- In posttraumatic arthritis, the initial injury stimulates the production of inflammatory cytokines. Which
cytokine is produced at the highest level on the first day after injury?
1*Interleukin-6 (IL-6)
2*Interleukin-1 beta (IL-1β) IL -1B
TNF-a
3*Chemokine ligand 22 (CCL-22)
4*Damage-associated molecular patterns (DAMPs)
Correct answer 2
The development of arthritis after joint injury is common and can result from multiple causes,
including cartilage contusion, meniscal injury, ligament tear, or intra-articular fracture. The accuracy
of reduction does not necessarily prevent the development of posttraumatic arthritis. Data from
animal studies of posttraumatic arthritis demonstrate the production of inflammatory cytokines that
lead to chondrocyte death and matrix destruction. In the first few days after injury IL-
1β (predominantly) and tumor necrosis factor alpha are the primary cytokines produced, followed by
nitric oxide, matrix metalloproteinases, and aggrecanases, which degrade the chondral matrix CCL-22
increases at around 5 days after injury, however. Other factors called DAMPs, which are generated
through the mechanical or enzymatic degradation of joint tissues, also stimulate an innate
inflammatory response.
,3- What is the main function of lubricin in synovial joints?
1*Serves as a component of the extracellular matrix
2*Inhibits matrix metalloproteinase
3*Increases cross-linking between collagen fibers
4*Reduces the coefficient of friction in the joint
Correct answer 4
Lubricin reduces the friction between the surfaces in the joint, leading to decreased shear forces going
through the hyaline cartilage. It is a glycoprotein that is produced by the chondrocytes in the superficial
zone and is not a primary component of the extracellular matrix. A lack of lubricin has been associated
with syndromes causing arthritic changes at an early age
4- Anti-sclerostin antibody increases bone formation by targeting what molecular pathway?
1*Wnt
2*Bone morphogenetic protein (BMP)
3*Notch
4*Indian hedgehog
Correct answer 1
All of the listed factors serve critical functions in bone formation. Only BMP-based therapies currently
are FDA approved, however. Sclerostin is an extracellular antagonist of Wnt signaling and, to a lesser
extent, BMP signaling. Blosozumab currently is an investigational antibody therapy designed to block
sclerostin’s ability to inhibit Wnt signaling, netting a positive effect on bone formation. In a phase 2 trial
involving 120 postmenopausal women, 1 year of blosozumab treatment resulted in a 17% increase in
bone mineral density in the lumbar spine.
, 5- Figures f1 fthrough f3 fdisplay fradiographs fand fan fMRI ffrom fa f29-year-old fman fwho fhas
fcomplained fof fleft fleg fpain fsince fsustaining fa fgunshot fwound f18 fmonths fago. fHe fdenies fany
ffevers for fchills fbut fdoes fhave fpain fand fdrainage ffrom fhis fwound. fHis ferythrocyte fsedimentation
frate f(ESR) fis f105 fmm/h f(reference frange: f0-20 fmm/h), fC-reactive fprotein f(CRP) flevel fis f12 fmg/L
f(reference frange: f0.08-3.1 fmg/L), fwhite fblood fcell f(WBC) fcount fis f8,000 f/µL f(reference frange:
f4500-11000 f/µL), fand fvitamin fD flevel fis f15 fng/mL f(reference frange: f20-40ng/ml).
What fis fthe ftissue findicated fby fthe farrow fin fFigure
f4? fFigure f1
,1- In the context of joint arthroplasty, the alpha-defensin immunoassay test is useful for the detection
of?
1*aseptic loosening.
2*metal corrosion.
3*periprosthetic infection.
4*bone ingrowth.
Correct answer 3
Alpha-defensin is a protein released by activated neutrophils in response to infection. The detection of
alpha-defensin in synovial fluid is highly sensitive and specific as a marker of periprosthetic infection.
Aseptic loosening and the bone ingrowth of prostheses generally are detected radiographically. Metal
corrosion issues—in metal-on-metal prostheses, for example—generally are followed using blood metal
ion levels.
2- In posttraumatic arthritis, the initial injury stimulates the production of inflammatory cytokines. Which
cytokine is produced at the highest level on the first day after injury?
1*Interleukin-6 (IL-6)
2*Interleukin-1 beta (IL-1β) IL -1B
TNF-a
3*Chemokine ligand 22 (CCL-22)
4*Damage-associated molecular patterns (DAMPs)
Correct answer 2
The development of arthritis after joint injury is common and can result from multiple causes,
including cartilage contusion, meniscal injury, ligament tear, or intra-articular fracture. The accuracy
of reduction does not necessarily prevent the development of posttraumatic arthritis. Data from
animal studies of posttraumatic arthritis demonstrate the production of inflammatory cytokines that
lead to chondrocyte death and matrix destruction. In the first few days after injury IL-
1β (predominantly) and tumor necrosis factor alpha are the primary cytokines produced, followed by
nitric oxide, matrix metalloproteinases, and aggrecanases, which degrade the chondral matrix CCL-22
increases at around 5 days after injury, however. Other factors called DAMPs, which are generated
through the mechanical or enzymatic degradation of joint tissues, also stimulate an innate
inflammatory response.
,3- What is the main function of lubricin in synovial joints?
1*Serves as a component of the extracellular matrix
2*Inhibits matrix metalloproteinase
3*Increases cross-linking between collagen fibers
4*Reduces the coefficient of friction in the joint
Correct answer 4
Lubricin reduces the friction between the surfaces in the joint, leading to decreased shear forces going
through the hyaline cartilage. It is a glycoprotein that is produced by the chondrocytes in the superficial
zone and is not a primary component of the extracellular matrix. A lack of lubricin has been associated
with syndromes causing arthritic changes at an early age
4- Anti-sclerostin antibody increases bone formation by targeting what molecular pathway?
1*Wnt
2*Bone morphogenetic protein (BMP)
3*Notch
4*Indian hedgehog
Correct answer 1
All of the listed factors serve critical functions in bone formation. Only BMP-based therapies currently
are FDA approved, however. Sclerostin is an extracellular antagonist of Wnt signaling and, to a lesser
extent, BMP signaling. Blosozumab currently is an investigational antibody therapy designed to block
sclerostin’s ability to inhibit Wnt signaling, netting a positive effect on bone formation. In a phase 2 trial
involving 120 postmenopausal women, 1 year of blosozumab treatment resulted in a 17% increase in
bone mineral density in the lumbar spine.
, 5- Figures f1 fthrough f3 fdisplay fradiographs fand fan fMRI ffrom fa f29-year-old fman fwho fhas
fcomplained fof fleft fleg fpain fsince fsustaining fa fgunshot fwound f18 fmonths fago. fHe fdenies fany
ffevers for fchills fbut fdoes fhave fpain fand fdrainage ffrom fhis fwound. fHis ferythrocyte fsedimentation
frate f(ESR) fis f105 fmm/h f(reference frange: f0-20 fmm/h), fC-reactive fprotein f(CRP) flevel fis f12 fmg/L
f(reference frange: f0.08-3.1 fmg/L), fwhite fblood fcell f(WBC) fcount fis f8,000 f/µL f(reference frange:
f4500-11000 f/µL), fand fvitamin fD flevel fis f15 fng/mL f(reference frange: f20-40ng/ml).
What fis fthe ftissue findicated fby fthe farrow fin fFigure
f4? fFigure f1
