title: Early osteoarthritis of the knee.
abstract: There is an increasing awareness on the importance in identifying early phases of the degenerative processes in knee osteoarthritis (OA), the crucial period of the disease when there might still be the possibility to initiate treatments preventing its progression. Early OA may show a diffuse and ill-defined involvement, but also originate in the cartilage surrounding a focal lesion, thus necessitating a separate assessment of these two entities. Early OA can be considered to include a maximal involvement of 50 % of the cartilage thickness based on the macroscopic ICRS classification, reflecting an OARSI grade 4. The purpose of this paper was to provide an updated review of the current status of the diagnosis and definition of early knee OA, including the clinical, radiographical, histological, MRI, and arthroscopic definitions and biomarkers. Based on current evidence, practical classification criteria are presented. As new insights and technologies become available, they will further evolve to better define and treat early knee OA.
authors.affiliation: Center of Experimental Orthopaedics, Saarland University, Kirrberger Strasse 100, Building 37-38, 66421, Homburg/Saar, Germany. henning.madry@uks.eu.|Department of Orthopaedic Surgery, Saarland University Medical Center, Kirrberger Strasse 100, Building 37-38, 66421, Homburg/Saar, Germany. henning.madry@uks.eu.
authors.forename: Henning
authors.initials: H
authors.lastname: Madry
authors.affiliation: NABI Laboratory, Rizzoli Orthopaedic Institute, Via Di Barbiano, 1/10, 40136, Bologna, Italy.
authors.forename: Elizaveta
authors.initials: E
authors.lastname: Kon
authors.affiliation: Dipartimento di Ortopedia, Responsabile di Struttura Semplice di Traumatologia dello, Sport Knee Surgery and Sports Traumatology, Ospedale Sacro Cuore - Don Calabria, Via Don, Sempreboni, 5, 37024, Negrar, Verona, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Condello
authors.affiliation: IRCCS Istituto Ortopedico Galeazzi, Milan, Italy.|Department of Biomedical Sciences for Health, University of Milan, Milan, Italy.
authors.forename: Giuseppe M
authors.initials: GM
authors.lastname: Peretti
authors.affiliation: SportClinic Zürich, Klinik Hirslanden, Witellikerstrasse 40, 8032, Zurich, Switzerland.
authors.forename: Matthias
authors.initials: M
authors.lastname: Steinwachs
authors.affiliation: Service de Chirurgie Orthopédique, Centre de L'Appareil Locomoteur, de Médecine du Sport et de Prévention, Centre Hospitalier de Luxembourg-Clinique d'Eich and Sports Medicine Research Laboratory, Luxembourg Institute of Health, 78, rue d'Eich, 1460, Luxembourg, Luxembourg.
authors.forename: Romain
authors.initials: R
authors.lastname: Seil
authors.affiliation: Centro di Eccellenza per L'attività Ortopedica, Reumatologica e Riabilitativa, L'Istituto Ortopedico Gaetano Pini è un'Azienda Ospedaliera di rilievo nazionale, P.zza A. Ferrari, 1, 20122, Milan, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Berruto
authors.affiliation: Department of Orthopedic Surgery, Oslo University Hospital and Oslo Sports Trauma Research Center, 0407, Oslo, Norway.
authors.forename: Lars
authors.initials: L
authors.lastname: Engebretsen
authors.affiliation: Biomechanics Laboratory, II Orthopaedics and Traumatology Clinic, Rizzoli Orthopaedic Institute, Via Di Barbiano, 1/10, 40136, Bologna, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Filardo
authors.affiliation: Department of Trauma Surgery, University Medical Center Regensburg, Franz-Josef-Strauss-Allee 11, 93042, Regensburg, Germany.|Sporthopaedicum Regensburg, Hildegard von Bingen Strasse 1, 93053, Regensburg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Angele
mesh_terms: D001182:Arthroscopy; D015415:Biomarkers; D002358:Cartilage, Articular / Q000000981:diagnostic imaging* / Q000473:pathology; D018450:Disease Progression; D042241:Early Diagnosis; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000473:pathology; D008279:Magnetic Resonance Imaging; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000473:pathology; D011859:Radiography
chemical_list: D015415:Biomarkers
keywords: Biomarkers; Cartilage; Classification; Focal cartilage defect; Meniscus; OA; Osteochondral unit; Pain; Subchondral bone; Traumatic lesion