3- Synovial Fluid

Question 1

Where is the synovium in the axial skeleton?

Answer 1

joints, tendon sheaths, and bursae

Question 2

What is a Type A Synoviocyte?

Answer 2

i) Contain lysosome and remove debris in joints ii) Macrophage-like, derived from hematopoietic system

Question 3

What is a Type B Synoviocyte?

Answer 3

i) Secrete hyaluronic acid ii) Fibroblastic in nature, derived from mesenchyme

Question 4

What is the anatomical makeup of the synovium?

Answer 4

a) The synovium is usually 2-4 layers thick b) Synoviocytes cover structures subject to pressure and are spread out c) Loose cellular connections make the synovial lining semipermeable

Question 5

What is the topography of the synovium?

Answer 5

the lining consists of multiple villi and microvilli resulting in large surface area

Question 6

How does the articular cart get it’s metabolites?

Answer 6

synovial fluid provides the means of metabolite delivery. The large surface area and semipermeable nature of synovium allows for delivery of nutrients.

Question 7

What is the fxn of the synovial fluid?

Answer 7

Deliver nutrients to the articular cart.

Question 8

How is synovial fluid made?

Answer 8

It is formed by the filtration of capillary plasma through a sieve of hyaluronate molecules, allowing small molecule to pass through.

Question 9

What special thing does synovial fluid NOT have that prevents it from clotting?

Answer 9

fibrinogen (it’s too large to get in)

Question 10

Is synovial fluid viscous or not very viscous?

Answer 10

Very viscous (<– try saying that 10x fast)

Question 11

What substance causes the synovial fluid to be so viscous?

Answer 11

Hyaluronic acid

Question 12

What is synovitis?

Answer 12

inflammation of synovial lining from inflammatory or non-inflammatory joint disease

Question 13

What is bacterial septic arthritis?

Answer 13

most common monoarticular inflammatory arthritis. Inflammatory cells will release proteolytic enzymes that lead to rapid cartilage destruction

Question 14

How many PMN’s do you need to confirm a bacterial septic arthritis Dx on arthrocentesis?

Answer 14

>50,000/mm3

Question 15

What is the pathological process in rheumatoid arthritis (RA)?

Answer 15

deposition of Ag-Ab complexes w/in the synovium causes an inflammatory rxn that perpetuates a vicious cycle that causes joint destruction, starts in small joints of hands and feet and moves to larger joints

Question 16

What happens to the synovial cells in RA?

Answer 16

Hypertrophy and hyperplasia of synovial cells produce thickening of synovial membrane

Question 17

What happens to the synovial architecture in RA?

Answer 17

synovium to appear dense with a papillary architecture

Question 18

What is the presentation of RA?

Answer 18

i) Early on it manifests as edema and chronic inflammation of the synovium. ii) Later, as RA progresses subsynovial fibroblasts proliferate and deposit collagen fibers which forms the pannus. Eventually there is complete destruction of the articular cartilage, creating the “burnt out” joint, which may be fused by either fibrous or bony ankylosis.

Question 19

What is the pannus?

Answer 19

A proliferation of synovium beginning at the periphery of the joint surface

Question 20

What is the etiology of osteoarthritis (OA)?

Answer 20

slowly progressing degenerative joint disease that is associated with aging w/ an unknown etiology

Question 21

What is the pathophysiology of OA?

Answer 21

OA is caused by destruction of cartilage (compared to RA in which the synovium is also destroyed). Synovitis does occur, but is a result of cartilage destruction

Question 22

What is effusion?

Answer 22

the increase in intra-articular fluid.

Question 23

What causes effusion?

Answer 23

occurs when lysosomal enzymes of inflammatory cells break down the hyaluronic acid sieve barrier allowing large proteins to enter the synovial fluid.

Question 24

How can clots form when there is an effusion?

Answer 24

the hyaluronic acid barrier is broken down, larger molecules like fibrinogen can enter the synovial fluid and cause clots.

Question 25

Why is viscosity decreased when there is an effusion?

Answer 25

Since the viscosity of the fluid depends on [hyaluronic acid], as the hyaluronic acid is broken down its concentration dec so does the synovial fluid viscosity.

Question 26

Identify general characteristics of synovial fluid in different types of effusions. These include color, clarity, viscosity, WBC, glucose, crystals.

Answer 26

Question 27

What are the 4 examples of benign synovial tumors?

Answer 27

Hemangiomas, lipomas, pigmented villonodular synovitis, and synovial chondromatosis

Question 28

What is primary synovial chondromatosis?

Answer 28

a condition in which hyaline cartilage nodules grow w/in the synovial lining of a joint, bursa, or tendon sheath.

In this form the nodules of cartilage form de novo and are of hyaline cartilage, these nodules may calcify and form lamellar bone.

Question 29

What are the findings in primary synovial chondromatosis?

Answer 29

(1) Most common between 30-50, men are twice as affect as women
(2) Unilateral knee joint is most commonly affected
(3) Sx: pain, swelling, and mechanical symptoms (locking/giving way)
(4) Exam: effusion, palpable mass, tenderness, soft-tissue swelling, muscle atrophy and crepitus.

Question 30

What are secondary synovial chondromatosis?

Answer 30

cartilaginous nodules that form may detach and become loose bodies, which produces joint debris that sticks to synovium