title: Influence of age, site, and degenerative state on the speed of sound in equine articular cartilage.
abstract: OBJECTIVE
  To determine the speed of sound (SOS) in equine articular cartilage and investigate the influence of age, site in the joint, and cartilage degeneration on the SOS.
  
  
  METHODS
  Cartilage samples from 38 metacarpophalangeal joints of 38 horses (age range, 5 months to 22 years).
  
  
  METHODS
  Osteochondral plugs were collected from 2 articular sites of the proximal phalanx after the degenerative state was characterized by use of the cartilage degeneration index (CDI) technique. The SOS was calculated (ratio of needle-probe cartilage thickness to time of flight of the ultrasound pulse), and relationships between SOS value and age, site, and cartilage degeneration were evaluated. An analytical model of cartilage indentation was used to evaluate the effect of variation in true SOS on the determination of cartilage thickness and dynamic modulus with the ultrasound indentation technique.
  
  
  RESULTS
  The mean SOS for all samples was 1,696 +/- 126 m/s. Age, site, and cartilage degeneration had no significant influence on the SOS in cartilage. The analytical model revealed that use of the mean SOS of 1,696 m/s was associated with maximum errors of 17.5% on cartilage thickness and 70% on dynamic modulus in an SOS range that covered 95% of the individual measurements.
  
  
  CONCLUSIONS
  In equine articular cartilage, use of mean SOS of 1,696 m/s in ultrasound indentation measurements introduces some inaccuracy on cartilage thickness determinations, but the dynamic modulus of cartilage can be estimated with acceptable accuracy in horses regardless of age, site in the joint, or stage of cartilage degeneration.
authors.affiliation: Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 12, 3584 CM, Utrecht, The Netherlands.
authors.forename: Harold
authors.initials: H
authors.lastname: Brommer
authors.forename: Mikko S
authors.initials: MS
authors.lastname: Laasanen
authors.forename: Pieter A J
authors.initials: PA
authors.lastname: Brama
authors.forename: P René
authors.initials: PR
authors.lastname: van Weeren
authors.forename: Ab
authors.initials: A
authors.lastname: Barneveld
authors.forename: Heikki J
authors.initials: HJ
authors.lastname: Helminen
authors.forename: Jukka S
authors.initials: JS
authors.lastname: Jurvelin
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D002357:Cartilage Diseases / Q000473:pathology / Q000503:physiopathology / Q000662:veterinary*; D002358:Cartilage, Articular / Q000473:pathology / Q000503:physiopathology*; D005552:Forelimb; D006734:Horse Diseases / Q000473:pathology / Q000503:physiopathology*; D006736:Horses; D013016:Sound