title: Ultrasonic quantitation of superficial degradation of articular cartilage.
abstract: Ultrasound (US) has been suggested as a means for the quantitative detection of early osteoarthrotic changes in articular cartilage. In this study, the ability of quantitative US 2-D imaging (20 MHz) to reveal superficial changes in bovine articular cartilage after mechanical or enzymatic degradation was investigated in vitro. Mechanical degradation was induced by grinding samples against an emery paper with the grain size of 250 microm, 106 microm, 45 microm or 23 microm. For enzymatic degradation, samples were digested with collagenase, trypsin or chondroitinase ABC. Variations of the US reflection coefficient induced by the degradation were investigated. Furthermore, two novel parameters, the US roughness index (URI) and the spatial variation of the US reflection coefficient (SVR), were established to quantitate the integrity of the cartilage surface. Statistically significant decreases (p < 0.05) in US reflection coefficient were observed after mechanical degradations or enzymatic digestion with collagenase. Increases (p < 0.05) in URI were also revealed after these treatments. We conclude that quantitative US imaging may be used to detect collagen disruption and increased roughness in the articular surface. These structural damages are typical of early osteoarthrosis.
authors.affiliation: Department of Applied Physics, University of Kuopio, Kuopio, Finland. saarakka@hytti.uku.fi
authors.forename: Simo
authors.initials: S
authors.lastname: Saarakkala
authors.forename: Juha
authors.initials: J
authors.lastname: Töyräs
authors.forename: Jani
authors.initials: J
authors.lastname: Hirvonen
authors.forename: Mikko S
authors.initials: MS
authors.lastname: Laasanen
authors.forename: Reijo
authors.initials: R
authors.lastname: Lappalainen
authors.forename: Jukka S
authors.initials: JS
authors.lastname: Jurvelin
mesh_terms: D000818:Animals; D002357:Cartilage Diseases / Q000000981:diagnostic imaging* / Q000209:etiology / Q000473:pathology; D002358:Cartilage, Articular / Q000000981:diagnostic imaging* / Q000648:ultrastructure; D002417:Cattle; D007091:Image Processing, Computer-Assisted / Q000379:methods; D010003:Osteoarthritis / Q000000981:diagnostic imaging*; D013314:Stress, Mechanical; D013499:Surface Properties; D014463:Ultrasonography