Joint Degeneration (DRAFT) Flashcards
define degeneration
disease in which function/structure of affected tissue/organs changes for the worse over time
what factors would increase risk for more severe or earlier clinical presentation of joint degeneration?
^mechanical forces
define osteoarthritis
implies inflammatory mediation (caused by inflammation)
define osteoarthrosis
mechanical breakdown of joints (is not caused by inflammation)
define joint degeneration
mechanical breakdown of joint (lacking well-defined SSx)
joint degeneration is characterized by progressive destruction of ____ at ____ joints
articular cartilage; synovial joints
what is secondary joint degeneration due to?
underlying cause = ^mechanical breakdown
- congenital / acquired incongruity of joints
- trauma
- inflammatory arthritis
- crystal deposits (crystaline arthropathies)
- infection
- metabolic or endocrine diseases
what is the most common joint problem in humans?
joint degeneration
what are the general aspects of joint degeneration?
cartilage breakdown, non-inflammatory, progressive, age related
what is the etiology of primary joint degeneration?
unknown
- aging
- weight bearing joints
- repetitive loading / use of specific joints
- intrinsic cartilage defects
- genetic factors related to cartilage formation (mutations in Type II collagen gene COL2A1)
what are the symptoms of joint degeneration?
variable symptoms (has defined signs, not symptoms)
what population is most commonly affected by joint degeneration?
85% of 75-79yrs
when is joint degeneration more common in men? women?
men: before age 45
women: after age 55
is joint degeneration classified as a physiological process or a pathology?
both normal physiological process AND pathology
what are some etiological factors that play into secondary joint degeneration?
- increased unit load
- disruption of H20 bonding
- subchondral stiffening
- biochemical changes
- early joint degeneration (reparative response)
what are some examples of subchondral stiffening?
- subchondral sclerosis
- acromegaly
- Paget’s
describe the biochemical changes that result in joint degeneration.
- decreased proteoglycans: chondrocytes die
- reduced glycosaminoglycan chain length
- ^fibrillin
- ^water binding
- collagenase present
early joint degeneration is a ____ response
Reparative
what is the pathogenesis of joint degeneration?
- proteoglycan synthesis decreases, chondrocyte death increases
- fibrillation/cracking/fissuring in surface layers of articular cartilage
- fibrillation propagation
- cracks cross tide mark
- fibrocartilage plug may be broken down
- eburnated bone cracks
- osteophytes may develop at joint margins
what happens during the fibrillation propagation step of the pathogenesis of joint degeneration?
- synovial fluid fills defects, increasing fissuring
- pieces of cartilage may break off
what occurs when cracks cross the tide mark in the pathogenesis of joint degeneration?
- angiogenesis
- ^osteoclast activity = subchondral resorption
- ^osteoblastic activity = subchondral sclerosing + subchondral cysts
- fibrocartilage forms (patching that eventually falls out)
what occurs when the fibrocartilage plug breaks down during joint degeneration?
- exposes subchondral bone to mechanical erosion
- eburnation
- subchondral sclerosing
what occurs when eburnated bone cracks during joint degeneration?
- cracks fill w/ synovial fluid
- subchondral cysts form and may increase in size
what is eburnation?
sclerosis + smoothing of 2 bony surfaces rubbing together