title: Arthroscopic Ultrasound Assessment of Articular Cartilage in the Human Knee Joint: A Potential Diagnostic Method.
abstract: OBJECTIVE
  We tested whether an intra-articular ultrasound (IAUS) method could be used to evaluate cartilage status arthroscopically in human knee joints in vivo.
  
  
  METHODS
  Seven patients undergoing arthroscopic surgery of the knee were enrolled in this study. An ultrasonic examination was conducted using the same portals as in the arthroscopic surgery. A high-frequency (40-MHz) ultrasound transducer (diameter = 1 mm) was directed to the desired location on the articular surface under arthroscopic control. In addition to ultrasound data, an IAUS video and optical video through the arthroscope were recorded. Classification of cartilage injuries according to International Cartilage Repair Society, as conducted by the orthopedic surgeon, provided reference data for comparison with the IAUS.
  
  
  RESULTS
  The IAUS method was successful in imaging different characteristics of the articular surfaces (e.g., intact surface, surface fibrillation, and lesions of varying depth). In some cases, also the subchondral bone and abnormal internal cartilage structure were visible in the IAUS images. Specifically, using the IAUS, a local cartilage lesion of 1 patient was found to be deeper than estimated arthroscopically.
  
  
  CONCLUSIONS
  The IAUS method provided a novel arthroscopic method for quantitative imaging of articular cartilage lesions. The IAUS provided quantitative information about the cartilage integrity and thickness, which are not available in conventional arthroscopy. The present equipment is already approved by the Food and Drug Administration for intravascular use and might be transferred to intra-articular use. The invasiveness of the IAUS method might restrict its wider clinical use but combined with arthroscopy, ultrasonic assessment may enlarge the diagnostic potential of arthroscopic surgery.
authors.affiliation: Department of Physics and Mathematics, University of Eastern Finland, Kuopio Campus, Kuopio, Finland.
authors.forename: Erna
authors.initials: E
authors.lastname: Kaleva
authors.affiliation: Department of Physics and Mathematics, University of Eastern Finland, Kuopio Campus, Kuopio, Finland.
authors.forename: Tuomas
authors.initials: T
authors.lastname: Virén
authors.affiliation: Department of Physics and Mathematics, University of Eastern Finland, Kuopio Campus, Kuopio, Finland ; Department of Diagnostic Radiology, University of Oulu, Oulu, Finland.
authors.forename: Simo
authors.initials: S
authors.lastname: Saarakkala
authors.affiliation: Department of Orthopaedics and Traumatology, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Janne
authors.initials: J
authors.lastname: Sahlman
authors.affiliation: Department of Orthopaedics and Traumatology, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Joonas
authors.initials: J
authors.lastname: Sirola
authors.affiliation: Orthopaedic Research Laboratory, University of Helsinki, Helsinki, Finland.
authors.forename: Jani
authors.initials: J
authors.lastname: Puhakka
authors.affiliation: Department of Orthopaedics and Traumatology, Helsinki University Hospital, Helsinki, Finland.
authors.forename: Teemu
authors.initials: T
authors.lastname: Paatela
authors.affiliation: Department of Orthopaedics and Traumatology, Kuopio University Hospital, Kuopio, Finland ; Bone and Cartilage Research Unit, University of Eastern Finland, Kuopio, Finland.
authors.forename: Heikki
authors.initials: H
authors.lastname: Kröger
authors.affiliation: Orthopaedic Research Laboratory, University of Helsinki, Helsinki, Finland ; Department of Orthopaedics and Traumatology, Helsinki University Hospital, Helsinki, Finland.
authors.forename: Ilkka
authors.initials: I
authors.lastname: Kiviranta
authors.affiliation: Department of Physics and Mathematics, University of Eastern Finland, Kuopio Campus, Kuopio, Finland.
authors.forename: Jukka S
authors.initials: JS
authors.lastname: Jurvelin
authors.affiliation: Department of Physics and Mathematics, University of Eastern Finland, Kuopio Campus, Kuopio, Finland ; Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Juha
authors.initials: J
authors.lastname: Töyräs
keywords: arthroscopy; cartilage; knee; subchondral bone; ultrasound