MSK 2 - Articular Structure and Pathology Flashcards
What is a synovial joint composed of?
Joint capsule: Fibrous joint capsule (outer layer) and synovial membrane (inner layer)
Joint space
Synovial fluid
Articular cartilage
What is the outer layer of the joint capusule?
Fibrous capsule or stratum fibrosum
What kind of blood supply does the fibrous capsule have?
Poor blood supply BUT rich in joint receptors (sensory receptors)
What is the function of the synovium?
produce synovial fluid
What do type B cells of the synovium do?
Secrete hyaluronate (HA) = gel that improves viscosity of synovial fluid and attracts H2O
Secrete lubricin (glycoprotein) = reduce friction
What do type A cells of the synovium do?
Secrete immunoglobulins
Secrete lysosomal enzymes
What is synovial fluid?
Clear viscous fluid
Provides lubrication for joint surface –> frictionless surfaces between bones
What are thixotrophic properties?
Viscosity varies inversely w/ velocity of movement:
Rest - synovial fluid resists movement of joint
Movement - synovial fluid provides less resistance to movement
What is hyaline articular cartilage?
Thin covering on the ends of most bones
What does hyaline articular cartilage do?
Reduces friction
Absorb/disperse compressive forces
What is articular cartilage composed of?
Cellular component
Extra-cellular matrix
What is the cellular component of articular cartilage?
Chondroblasts (chondrocytes)
What do chondrocytes to?
Produce/maintain extra-cellular matrix
How much of cartilage do chondrocytes make up?
2%
What makes up the non-fibrous component of the extra-cellular matrix?
Proteins
Proteoglycans
(makes up 5 - 10%)
What does the non-fibrous component of the extra-cellular matrix do?
Regulate fluid flow in/out of cartilage (water = 60 - 80% of cartilage)
What makes up the fibrous component of the extra-cellular matrix?
Collagen fibers
What do collagen fibers do in the extra-cellular matrix?
Arranged to absorb mechanical stress
How much of the cartilage is made of collagen?
10 - 30%
What is zone 1 of the cartilage-bone interface?
Smooth surface –> reduce friction of joint surface
What are zone 2 and zone 3 of the cartilage-bone interface?
Transitional zones –? absorb compressive forces
What is the tidemark of the cartilage - bone interface?
Interface between uncalcified and calcified layers
What is zone 4 of the cartilage-bone interface?
Calcified cartilage –> anchors cartilage to bone
What are the stimuli for matrix turnover?
Enzymes from chondrocytes
Hormones: GH/IGF
Mechanical Load: weight bearing
What does weight bearing activity do in healthy cartilage?
Push fluid (water/synovial fluid) out of cartilage
What happens to fluid flow during weight bearing activity in healthy cartilage as the cartilage becomes more compressed?
Fluid flow out becomes slower and resistnace becomes exponentially harder
**prevent ALL of the fluid from flowing out of the cartilage
What is responsible for regulating fluid flow in/out of cartilage?
Proteoglycans
What is the net result of fluid flow in/out of cartilage w/ compression?
Protects against compressive forces
Allows for nutrients to pass in/out of cartilage to reach chondrocytes
Does articular cartilage have blood/nerve supply?
No
**pain results from inflammation/swelling/irritation of pain sensitive tissues such as joint capsule/synovium, periosteum
How does articular cartilage heal after its been injured?
Poor ability to regenerate d/t poor blood supply
What is the most common joint disease?
Osteoarthritis
What is the primary defect of osteoarthritis?
Loss/disruption of articular cartilage –> matrix destruction involving chondrocytes, collagen and proteoglycans
What are the enzymatic changes seen in osteoarthritis?
Excessive enzyme secretion from chondrycytes –> matrix breakdown
Ezymes from synovium also contribute to matrix (collagen) breakdown
**loss of proteoglycans in cartilage disrupts fluid regulation (H2O flows in/out too easily)
What are the hormone changes seen in osteoarthritis?
Chondrocytes become less sensitive to GH/IGF
What are the cytokine changes seen in osteoarthritis?
Excessive production of IL-1 –> inhibition of normal cytokine regulation of matrix turnover
- *IL-1 facilitates NO synthesis
- *IL-1 = inflammatory cytokine
What is found in synovial fluid and synovium in the joints of pts w/ osteoarthritis that is not found in normal joints?
Nitric Oxide
What does nitric oxide do in the joints of pts w/ osteoarthritis?
Chondrycyte apoptosis
What are the fluid changes @ rest that occur w/ osteoarthritis?
Increased volume of water w/ in cartilage
What are the fluid changes during weight bearing activity that occur w/ osteoarthritis?
Fluid is pushed out rapidly
Cartilage is easily compressed w/o much resistance
**relase of wt bearing allows increased volume of fluid to re-enter cartilage
What is the net result of the fluid changes during weight bearing activity that occur w/ osteoarthritis?
Cartilage has limited ability to absorb foces and provide adequate nutrients to chondrocytes
How does osteoarthritis effect surrounding structures (besides articular cartilage)?
Cause bone sclerosis and bone cysts
Osteophyte formation –> irritation
Synovial thickening –> loss of gross movement
What are the risk factors of osteoarthritis?
Trauma/Genetics = largest risk
Joint/ligament laxity
Inflammatory conditions
Neurological disorders –> abnormal movements –> damage joints
Exercise –> high impact sports
What are the typical radiolgoical (X-ray) findings associated w/ osteoarthritis?
Heberden’s Nodes - DIP joints
Bouchard’s Nodes - PIP joints
What are the pain patterns typical of osteoarthritis?
Morning pain
Pain following prolonged postural positions (same position for long periods of time)
Describe how pain may refer in osteoarthritis?
Hip may refer to knee
Hip may refer to ankle
Knee may refer to hip
How are the joints affected in osteoarthritis?
Joint capsule thickening –> deformation
Loss of function/mobility
What is the conservative treatment for osteoarthritis?
Changes in exercise, joint mobility, lifestyle
What are the pharmaceutical treatments for osteoarthritis?
Symptomatic relief –> over the counter to narcotics
What are the surgical treatments for osteoarthritis?
Viscosupplementation
Cartilage “repair” strategies
Joint Replacement (arthroplasty)
What is Viscosupplementation?
Inject hyaluronates (gel like substance) into joint space to improve viscous properties of synovial fluid
What are the cartilage repiar strategies for osteoarthritis?
Arthroscopic lavage and debridement
Marrow stimulating techniques (microfracture)
Osteochondral autografts and allografts (OATS) –> make chondrocytes in lab from pts own bone and inject it into joint
When would you do a joint replacement in a pt w/ osteoarthritis?
Last resort
If all other strategies have failed or are not appropriate
What are infectious inflammatory joint disease?
Inflammation directly d/t bacteria, virus, fungi, protozoa etc
**Lyme dz, Rocky Mt Spotted Fever
What are non-infectious inflammatory joint disease?
Inflammation d/t autoimmune reax
**Rheumatoid Arthritis, Juvenile Rheumatoid Arthritis, Gout, Ankylosing Spondylitis
What is Rheumatoid Arthritis?
Systemic autoimmune disorder that causes chronic inflammation of connective tissues, primarily joints
What are the primary tissues involve in Rheumatoid Arthritis?
Synovial membrane
What are the secondary tissues involve in Rheumatoid Arthritis?
Chronic inflammation gradually destroys:
Articular Cartilage
Fibrous Joint Capsule
Menisci
Surrounding Ligaments/tissue
Bone
What are the most common joints involved w/ Rheumatoid Arthritis?
Fingers, Wrist, Elbow
Knee, Ankle, Foot
Which joints are usually the first to become symptomatic w/ Rheumatoid Arthritis?
MP Joints
PIP Joints
Wrists
Who are most affected by Rheumatoid Arthritis, men or women?
Female:Male (3:1)
**Peak age = 35 - 45
What is rheumatoid factor?
“New antibodies” –> combine w/ IgM, IgG and sometimes IgA and attack tissue
**called autoimmune complexes
What is the stimulus of rheumatoid arthritis?
Antigen of unknown cause combined w/ genetic susceptibility
What is the result of the stimulus of rheumatoid arthritis?
CD4 T helper cells and B lymphocytes are activated in the synovial fluid
What do B lymphocytes do in rheumatoid arthritis?
Facilitate the formation of rheumatoid factor –> facilitates formation of autoimmune complexes that are deposited in joint tissue
What do CD4 T helper cells do in rheumatoid arthritis?
Facilitate release of inflammatory enzymes that have destructive effect on structures (synovium, articular cartilage, joint capsule, tendons/ligaments)
Facilitates release of RANKL –> promotes osteoclastic activity, creating erosive lesions in the bone surrounding the joint
What are the general systemic manifestations of inflammation in rheumatoid arthritis?
Fever
Fatigue
Weakness
Anorexia
Weight Loss
General Achiness/Stiffness
What are the local manifestations of inflammation in rheumatoid arthritis?
Joint = paintful, tender and stiff
Morning stiffness
Progressive joint limitation d/t pain and gradual destruction
What are the hand deformities that are typical of rheumatoid arthritis?
Z deformity
Swan-neck
Boutonniere deformities
What does the z deformity of rheumatoid arthritis look like?
Radial deviation of the wrist
Ulnar deviation of the fingers
What does the swan-neck deformity of rheumatoid arthritis look like?
Extended PIP
Flexed DIP
What does the Boutonniere deformity of rheumatoid arthritis look like?
Flexed PIP
Extended DIP
What is a pannus formation or cloth cover seen in rheumatoid arthritis?
Granulation tissue (scar tissue) that covers articular surface
What happens if patients have an extra-articular manifestations of rheumatoid arthritis?
Have increased mortality rate
More severe disability
What are the cardiac manifestations seen with high-titer rheumatoid arthritis?
Pericarditis
Cardiomyopathy
Valvular incompetence
**caused by nodules and interstitial fibrosis
What are the eye manifestations seen with high-titer rheumatoid arthritis?
Scleritis –> suggests poor prognosis
What are extrasynovial rheumatoid nodules seen with high-titer rheumatoid arthritis?
Nodules seen in cutaneous areas that are under pressure or exposed to trauma
**MC on elbows/fingers
What are the nervous system manifestations seen with high-titer rheumatoid arthritis?
Neuropathies –> peripheral nerve compression
What are the kidney manifestations seen with high-titer rheumatoid arthritis?
Amyloid deposition
What are the hematopoietic system (Felty’s syndrome) manifestations seen with high-titer rheumatoid arthritis?
Anemia
Splenomegaly
Leukopenia
What are the vascular manifestations seen with high-titer rheumatoid arthritis?
Vasculitis
How is the diagnosis of rheumatoid arthritis made?
4 or more of following signs and symptoms and if symptoms are present for more than 6 weeks:
Morning stiffness > 1 hr
Arthritis of 3+ joints
Arthritis of hands
Symmetrical involvement
Rheumatoid nodules over extensor surfaces or bony prominences
Elevated rheumatoid factor present –> know this one!
How is rheumatoid arthritis treated?
Activity modifications –> limit exercise
Meds –> reduce inflammation, inhibit immune responses, rheumatic disease modifying drugs
Surgery –> correct deformity, correct mechanical imbalances
How many cases of adult rheumatoid arthritis begin in childhood?
5%
**F > M
Is juvenile rheumatoid arthritis pain as severe as adult?
No
**kid may be able to walk on affected joint
What are the the things that differ between juvenile rheumatoid arthritis and adult rheumatoid arthritis?
Antinuclear antibodies
Large joints affected
More often involves the cervical spine
What is gout?
Result of hyperurcemia –> joint destructionsoft tissue deposits and kidney damage
Who is affected more by gout, men or women?
M > F (7:1 to 9:1)
Which part of the body is usually affected by gout?
Big toe
Where does uric acid come from?
End product of purine metabolism
**excess synthesis or reduced elimination of uric acid = hyperurcemia
Where does the excess uric acid in the blood deposit?
Connective tissues surounding joint –> bursae, ligaments, articular cartilage, synovial membranes
What happens when uric acid saturates the synovial fluid?
Crystallizes
What do the urate crystals do in the joint?
Provokes inflammatory response –> joint destruction
What is tophus?
Subcutaneous deposits d/t chronic elevation of uric acid
Where is the first attack of gout usually?
90% = MTP (metatarsal-phalageal) jointo f the first toe
What are the signs/symptoms of a gout attack?
Joint = swollen and warm
Decreased weight bearing d/t pain
Fever, tachycardia, fatigue
How long do gout attacks usually last?
2 - 3 days
**spontaneous remission w/ reoccurrence
What happens to gout attacks as the disease progresses?
Get closer together
Where do tophi (plueral of tophus) deposit?
Ears
Elbows
Patella
**subcutaneous regions
What can happen to kindneys in pts w/ gout?
Kidney damaged by deposits of uric acid
Renal Stones
What are some chronic diseases associated w/ gout?
Alcoholism
Obesity
HTN
Hypertriglyceridemia
CAD
What are some other predisposing conditions for gout?
Increased dietary purine intake: organ meat, seafood, goose, bouillon, broth, yeast, gravy
Decreased purine biosynthesis (lack of uricase enzyme)
Prolonged use of diuretics (thiazides)
What is ankylosing spondylitis?
Chronic inflammatory joint dz –> stiffening and fusion of the spine and SI joint
What is the antigen that is associated w/ ankylosing spondylitis?
HLA-B27 (human leukocyte antigen) –> 90% of pts are (+) for this
Describe the pathology of ankylosing spondylitis?
Immune/inflammation response attack fibrocartilage structures of the joints
What structures of the joint are attacked in ankylosing spondylitis?
Joint capsule
Intervertebral discs
Etheses = attachment sites of tendon, ligament and joint capsule
Periosteum
