title: Quantitative Evaluation of the Mechanical Risks Caused by Focal Cartilage Defects in the Knee.
abstract: Focal cartilage lesions can proceed to severe osteoarthritis or remain unaltered even for years. A method to identify high risk defects would be of utmost importance to guide clinical decision making and to identify the patients that are at the highest risk for the onset and progression of osteoarthritis. Based on cone beam computed tomography arthrography, we present a novel computational model for evaluating changes in local mechanical responses around cartilage defects. Our model, based on data obtained from a human knee in vivo, demonstrated that the most substantial alterations around the defect, as compared to the intact tissue, were observed in minimum principal (compressive) strains and shear strains. Both strain values experienced up to 3-fold increase, exceeding levels previously associated with chondrocyte apoptosis and failure of collagen crosslinks. Furthermore, defects at the central regions of medial tibial cartilage with direct cartilage-cartilage contact were the most vulnerable to loading. Also locations under the meniscus experienced substantially increased minimum principal strains. We suggest that during knee joint loading particularly minimum principal and shear strains are increased above tissue failure limits around cartilage defects which might lead to osteoarthritis. However, this increase in strains is highly location-specific on the joint surface.
authors.affiliation: Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211 Kuopio, Finland.|Cancer Center, Kuopio University Hospital, POB 100, FI-70029 KUH, Kuopio, Finland.
authors.forename: Mikko S
authors.initials: MS
authors.lastname: Venäläinen
authors.affiliation: Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211 Kuopio, Finland.
authors.forename: Mika E
authors.initials: ME
authors.lastname: Mononen
authors.affiliation: Department of Orthopaedics, Traumatology and Hand Surgery, Kuopio University Hospital, POB 100, FI-70029 KUH, Kuopio, Finland.|Hospital Mehiläinen, FI-00260, Helsinki, Finland.
authors.forename: Jari
authors.initials: J
authors.lastname: Salo
authors.affiliation: Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211 Kuopio, Finland.
authors.forename: Lasse P
authors.initials: LP
authors.lastname: Räsänen
authors.affiliation: Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211 Kuopio, Finland.|Diagnostic Imaging Center, Kuopio University Hospital, POB 100, FI-70029 KUH, Kuopio, Finland.
authors.forename: Jukka S
authors.initials: JS
authors.lastname: Jurvelin
authors.affiliation: Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211 Kuopio, Finland.|Diagnostic Imaging Center, Kuopio University Hospital, POB 100, FI-70029 KUH, Kuopio, Finland.
authors.forename: Juha
authors.initials: J
authors.lastname: Töyräs
authors.affiliation: Cancer Center, Kuopio University Hospital, POB 100, FI-70029 KUH, Kuopio, Finland.
authors.forename: Tuomas
authors.initials: T
authors.lastname: Virén
authors.affiliation: Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211 Kuopio, Finland.|Diagnostic Imaging Center, Kuopio University Hospital, POB 100, FI-70029 KUH, Kuopio, Finland.
authors.forename: Rami K
authors.initials: RK
authors.lastname: Korhonen
mesh_terms: D000328:Adult; D001175:Arthrography / Q000295:instrumentation / Q000379:methods*; D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000000981:diagnostic imaging* / Q000473:pathology; D019902:Chondrocytes / Q000473:pathology; D003198:Computer Simulation; D054893:Cone-Beam Computed Tomography; D003287:Contrast Media / Q000008:administration & dosage; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000473:pathology; D020342:Finite Element Analysis; D006801:Humans; D007485:Ioxaglic Acid / Q000008:administration & dosage; D007718:Knee Injuries / Q000000981:diagnostic imaging* / Q000473:pathology; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008953:Models, Anatomic; D011312:Pressure; D018570:Risk Assessment; D013314:Stress, Mechanical; D013977:Tibia / Q000000981:diagnostic imaging / Q000473:pathology
chemical_list: D003287:Contrast Media; D007485:Ioxaglic Acid