Pathology of Joints Flashcards
What are joints, or articulations?
place where two or more bones are united by fibrous, elastic, or cartilaginous tissues or a combination of these tissues
What are the 3 types of joints? Give examples of each.
- FIBROUS JOINTS: synarthroses; bones united by fibrous tissue (between cranial bones, between teeth and alveolar bones
- CARTILAGINOUS JOINTS: amphiarthroses; bones united by hyaline cartilage (costochondral joints) or fibrocartilage (pelvic and mandibular symphyses, intervertebral joints)
- SYNOVIAL JOINTS: true joints, diarthroses; bone ends covered by hyaline articular cartilage and surrounded by articular capsule filled with synovial fluid
Synovial joint:
What type of joint is most likely to have lesions in domestic animals?
diarthrodial joints (synovial joints)
What are the 3 joint reactions to injury?
- FIBRILLATION (fraying) - articular cartilage erosion causing collage exposure and proteoglycan loss
- eburnation - articular cartilage ulceration
- joint mice formation
What happens to the subchondral bone underneath eburnated cartilage?
- bone will rub bone and cause pain (nerve endings in bone and not cartilage)
- becomes increasingly dense (osteosclerosis) to support trauma
- inflammation
What causes osteophyte formation? What is it? Where is this most common?
chronic joint injury - nodular proliferation of bone covered by cartilage
chondro-osseous margin where increased mobility occurs
What is villous hypertrophy/hyperplasia?
thickening of the usually thin and translucent synovial membrane due to chronic joint injury (finger-like projections)
(loss of cartilage from femur head)
What is pannus formation?
fibrovascular (granulation) and histiocytic tissue that develops within the synovial membrane at its junction with the periosteum and cartilage margins (transitional zone) and can spread over the articular surfaces as a velvety membrane
What does the infiltration of inflammatory cells in the pannus formation cause?
(+ collagenases from synovial fibroblasts) can further damage the articular cartilage and lead to ankylosis, or fixation, of the joint
What does “end-stage joint” mean? What do affected joints exhibit?
- generic term to describe a joint with severe chronic injury
- variable degrees of damage to the articular cartilage, deformation, osteophyte and pannus formation, capsular fibrosis, synovial villous hypertrophy/hyperplasia, and occasional ankylosis
What is osteochondrosis (dyschondroplasia)? What is a common sequel?
developmental joint disease characterized by abnormal growth and maturation of the articular cartilage
- severe degenerative joint disease
What is osteochondrosis (dyschondroplasia) the most common cause of? What is thought to affect pathogenesis?
- lameness in domestic animals, especially swine, horses, poultry, and large breed dogs (rapidly growing pigs can reach 100% incidence)
- ischemic damage to the growing cartilage due to an unknown and underlying cause
What is osteochondrosis/osteochondritis dissecans (OCD)? What does this cause in the synoial joint?
form of osteochondrosis characterized by the separation of a piece (flap) of articular cartilage from the subchondral bone
formation of joint mice that are able to use the nutrient-filled synovial fluid to survive and grow
When is osteochondrosis/osteochondritis dissecans (OCD) most common? What syndrome is commonly caused when it affects the elbow?
young, fast-growing males of large/giant breeds, commonly affecting shoulder and elbow joints
elbow dysplasia syndrome - ununited anconeal process and fragmented medial coronoid process of the ulna
How does osteochondrosis/osteochondritis dissecans (OCD) affect horses?
- common cause of lameness in foals and younger horses
- lesions can be widespread, but the stifle, hock, and fetlock joints are most commonly affected sites
OCD, dog humerus:
OCD, horse distal femur:
focal cartilage ulceration on trochlea with surrounding discoloration
OCD, pig humerus:
- thickness is not uniform
- ischemia of subcondral bone that is beginning the flap formation process