title: Cryopreserved and frozen hyaline cartilage imaged by environmental scanning electron microscope. An experimental and prospective study.
abstract: OBJECTIVE
  To obtain images of the articular surface of osteochondral grafts (fresh, frozen, and cryopreserved in RPMI) using an environmental scanning electron microscope (ESEM). To evaluate and compare the main morphological aspects of the chondral surface of the fresh, frozen, and cryopreserved grafts as visualized via ESEM.
  
  
  METHODS
  The study was based on osteochondral fragments from the internal condyle of the knee joint of New Zealand rabbits, corresponding to the chondral surface from fresh, frozen, and cryopreserved samples. One hundred ESEM images were obtained from each group and then classified according to a validated system. The kappa index and the corresponding concordance index were calculated, and the groups were compared by Pearson's chi-squared test (p < 0.05).
  
  
  RESULTS
  The articular surface of cryopreserved osteochondral grafts had fewer even surfaces and filled lacunae and a higher number of empty lacunae as compared to fresh samples; these differences correspond to images of cell membrane lesions that lead to destruction of the chondrocyte. Frozen grafts showed more hillocky and knobby surfaces than did fresh grafts; they also had a greater number of empty chondrocyte lacunae.
  
  
  CONCLUSIONS
  ESEM is useful for obtaining images of the surface of osteochondral grafts. When compared to fresh samples, cryopreservation in RPMI medium produces changes in the surface of hyaline cartilage, but to a lesser extent than those produced by freezing.
authors.affiliation: Department of Orthopaedic Surgery, University of Barcelona, Barcelona, Spain. ssastre@clinic.ub.es
authors.forename: Sergi
authors.initials: S
authors.lastname: Sastre
authors.forename: Santiago
authors.initials: S
authors.lastname: Suso
authors.forename: Josep-Maria
authors.initials: JM
authors.lastname: Segur
authors.forename: Guillem
authors.initials: G
authors.lastname: Bori
authors.forename: José-Antonio
authors.initials: JA
authors.lastname: Carbonell
authors.forename: Elba
authors.initials: E
authors.lastname: Agustí
authors.forename: Montse
authors.initials: M
authors.lastname: Nuñez
mesh_terms: D000818:Animals; D019645:Arthroplasty, Replacement, Knee; D002356:Cartilage / Q000473:pathology*; D015925:Cryopreservation; D004195:Disease Models, Animal; D007719:Knee Joint / Q000473:pathology*; D008137:Longitudinal Studies; D008855:Microscopy, Electron, Scanning; D011446:Prospective Studies; D011817:Rabbits