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 1 through 3 display radiographs and an MRI from a 29-year-old man who has complained of
left leg pain since sustaining a gunshot wound 18 months ago. He denies any fevers or chills but does
have pain and drainage from his wound. His erythrocyte sedimentation rate (ESR) is 105 mm/h
(reference range: 0-20 mm/h), C-reactive protein (CRP) level is 12 mg/L (reference range: 0.08-3.1
mg/L), white blood cell (WBC) count is 8,000 /µL (reference range: 4500-11000 /µL), and vitamin D
level is 15 ng/mL (reference range: 20-40ng/ml).
What is the tissue indicated by the arrow in Figure 4?
Figure 1
,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 1 through 3 display radiographs and an MRI from a 29-year-old man who has complained of
left leg pain since sustaining a gunshot wound 18 months ago. He denies any fevers or chills but does
have pain and drainage from his wound. His erythrocyte sedimentation rate (ESR) is 105 mm/h
(reference range: 0-20 mm/h), C-reactive protein (CRP) level is 12 mg/L (reference range: 0.08-3.1
mg/L), white blood cell (WBC) count is 8,000 /µL (reference range: 4500-11000 /µL), and vitamin D
level is 15 ng/mL (reference range: 20-40ng/ml).
What is the tissue indicated by the arrow in Figure 4?
Figure 1
