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35 Cards in this Set
- Front
- Back
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COX selectivity of corticosteroids:
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COX2
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What factors are important for normal function of HA?
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Concentration, molecular weight (degree of polymerization)
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Effects of IA HA:
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inhibition of chemotaxis, inhibition of phagocytosis of granulocytes & macrophages, reduced stimulation, proliferation & migration of lymphocytes, decrease release of PG, scavenge radicals
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Recommended molecular weight of HA:
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greater than 500 kDa
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Recommended dose of IA HA:
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20mg/ joint q 1 week for 3 weeks
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Effects of IV HA:
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improved lameness scores, improved synovial fluid parameters, decreased PGE2, decreased TP
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Examples of polysulfated polysaccharides:
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polysulfated glycosaminoglycan PSGAGs (adequan) and pentosan polysulfate
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Classification of polysulfated polysaccharides:
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(slow acting) disease modifying OA medications which prevent, retard, or reverse cartilaginous lesions
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What is PSGAG manufactured from?
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Bovine lung & trachea
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What is the main component of PSGAGs?
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Chondroitin sulfate
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Effects of IA PSGAGs:
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inhibit IL-1, MMP, PGE2, affect proteoglycan synthesis & degradation resulting in improved lameness scores, decreased radiographic OA progression, and improved joint capsule parameters
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What is pentosan manufactured from?
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Beech wood hemicellulose
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Effects of pentosan:
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reduced cartilage fibrillation
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Dose of pentosan:
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3mg/kg IM q 1 week for 4 weeks
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Dose of ASU:
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6 g/day
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What types of cartilages lesions do not heal spontaneously?
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Partial thickness lesions, and full thickness larger than 5mm
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How is the outcome of cartilage repair assessed?
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Biochemical content (type 2 collagen, aggrecan), histologic appearance resembling hyaline cartilage, biomechanical properties, functional outcome of the joint for the patient
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How are partial thickness lesions resurfaced?
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NOT converted to full thickness lesions, just conservative removal of fibrillated cartilage leaving the intact cartilage in place
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How are full thickness lesions resurfaced?
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Edges are debrided until cartilage is firmly attached to subchondral bone, fully removing the calcified cartilage, and leaving a sharp vertical border
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What are the 2 basic approaches to joint resurfacing?
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Stimulation of endogenous repair, transplantation or grafting of tissue
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What is the basis of stimulation of endogenous repair with joint resurfacing?
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Direct communication of defect with subchondral bone which has a good supply of stem cells and growth factors
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What GF are involved in cartilage repair?
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IGF-1, TGFB, BMP-2 & -7
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What surgical procedures facilitate access to bone marrow elements?
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Abrasion arthroplasty, spongialization, osteostixis, microfracture
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What is abrasion arthroplasty?
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Debridement to the level of the SCB plate
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What is spongialization?
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Debridement past the SCB plat into cancellous bone
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What is osteostixis?
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Focal drilling to the depth of cancellous bone in discrete locations in the cartilage lesion
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What is microfracture?
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Penetration of the subchondral bone in discrete locations in the cartilage lesion to produce petechial bleeding but does not enter cancellous bone
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What is the disadvantage of spongialization?
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Destabilization of the SCB plate
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What are the 2 prefered surgical methods of stimulating endogenous repair?
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Abrasion arthroplasty +/- microfracture
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When is microfracture not indicated?
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When the lesion extends into the subchondral bone
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What is the disadvantage of osteostixis?
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Thought to be related to the formation of subchondral bone cysts, heat generation from the drill leads to poorer healing
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What are the advantages of microfracture?
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Access cells & GF for healing without destabilizing SCB plate, greater volume of healing tissue in lesions, greater type 2 collagen in repair tissue
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how is microfracture performed?
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Lesion is debrided, then holes are spaced 2 to 3 mm apart to avoid communication and penetrate 2mm into the bone
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what are the disadvantages of osteochondral grafting procedures?
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Surgery is difficult and horses lack suitable non-weight bear donor tissues
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how are autologous chondrocytes used?
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Harvested for non-weight bearing tissue, minced cartilage is fibrin glued to a bioresorbable scaffold that is stapled to the subchondral bone in the defect
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