73. OC_OCD

Question 1

define osteochondrosis

Answer 1

developmental disorder of endochondral ossification in which growth cartilage at epiphysis and growth plate do not intern into boneoften bilateral; male; large to giant breedsOC latensOC manifestaOC dissecans

Question 2

growth plate vs epiphysis contributing to growth

Answer 2

physis— 75-80% growthepiphysis– 25 % growth

Question 3

4 zones of the growth plate

Answer 3

1. resting: near epiphysis, only vascularized area of growth plate; divide slowly, dispersed and small, flat2. proliferative: organized in columns, flat; dividing3. hypertrophic: column organization, spheroid, enlarge, synthesize matrix4. mineralization: organized in columns, mineralize and diemain determinants of bone length= proliferative and hypertrophy stage

Question 4

widely reported an accepted OC/OCD in dog

Answer 4

humeral headmedial humeral condylelateral or medial femoral condylemedial or lateral trochlear ridge of talusproposed (FCP, UAP, UME, retained ulnar core, TT avulsion, slipped capital physis, ununited caudal glenoid)

Question 5

4 zones of physis are different from 4 zones in articular cartilage

Answer 5

physisrestingproliferativehypertrophymineralizationarticular cartilagesuperficial (avascular)transitionalradial ————tidemark 23 week———calcifiedsubchondral bone***Different from growth plate in that the inner layer (calcified layer) is disorganized NOT columnar, and inner zones are vascular (unlike the inner zones of physis)

Question 6

etiology and risk factors for OC/OCD

Answer 6

poly genetic inheritance/genetic predispositionrapid growth (over feeding leads to incr factors stimulating chondrocyte differentiation and proliferation)dietary factors (hi cal, hi vit D)trauma

Question 7

most accepted theory of pathophysiology of articular OC/OCD

Answer 7

1. focal necrosis of epiphyseal cartilage canals result in ischemia/necrosis2. prevents endochondral ossification3. cells in area die and surrounding cells expand and increase matrix leading to thickening4. area becomes weak5. deform, fissure, cleft, detach

Question 8

grading of OC/OCD lesions in the proximal humerus

Answer 8

1. thickening2. small cleft3. larger cleft with underlying sclerotic subchondral bone4. detached cartilage flap or joint mice

Question 9

palliative and reparative techniques for OC/OCD treatment

Answer 9

debride, lavage are palliativereparative aim on enhancing natural healing and create vascular access channels 1. curettage–debride loose and necrotic bone2. spongialization–remove subchondral bone down to cancellous bone3. abrasion arthroplasty–grind eburnated bone down to healthy bleeding bone4. forage (osteostixis, subchondral drilling)–holes into bone5. microfracture–arthroscopic holes into bone

Question 10

restoration techniques for OC/OCD treatment

Answer 10

1. osteochondral transplants–OATsautogenous osteochondral grafts/plugs are donated from nonweightbearing portions (lateral/medial femoral condyle–medial sulcus terminalis) into defect2. mosiacplasty–filling full defect with small osteochondral transplants3. perichondral (costochondral junction) or periosteum (proximal media tibia) grafts to fill defects–not used in dogs4. autologous chondrocyte implantation (ACI)–not used in dogs

Question 11

T/Fcareful removal of the calcified cartilage layer prior to micro fracture appears to be a critical step for optimizing the amount and attachment of repair tissue to subchondral bone

Answer 11

true