title: Local Morphological Response of the Distal Femoral Articular-Epiphyseal Cartilage Complex of Young Foals to Surgical Stab Incision and Potential Relevance to Cartilage Injury and Repair in Children.
abstract: OBJECTIVE
  Describe the local morphological response of the articular-epiphyseal cartilage complex to surgical stab incision in the distal femur of foals, with emphasis on the relationship between growth cartilage injury, enchondral ossification, and repair.
  
  
  METHODS
  Nine foals were induced into general anesthesia at the age of 13 to 15 days. Four full-thickness stab incision defects were created in the cartilage on the lateral aspect of the lateral trochlear ridge of the left distal femur. Follow-up examination was carried out from 1 to 49 days postoperatively, including examination of intact bones, sawed slabs, and histological sections.
  
  
  RESULTS
  Incision defects filled with cells displaying fibroblast-, chondrocyte-, and osteoblast-like characteristics, potentially validating the rationale behind the drilling of stable juvenile osteochondritis dissecans lesions in children. Incisions induced necrosis within the cartilage on the margins at all depths of the defects. Sharp dissection may therefore be contraindicated in cartilage repair in young individuals. Incisions caused a focal delay in enchondral ossification in 2 foals, apparently related to the orientation of the incision defect relative to the direction of ossification. Defects became progressively surrounded by subchondral bone, in which granulation tissue containing clasts and foci of osteoblast-like cells was observed. Continued enchondral ossification was therefore likely to result in healing of uncomplicated defects to morphologically normal bone.
  
  
  CONCLUSIONS
  Epiphyseal growth cartilage injury had the potential to exert a negative effect on enchondral ossification. Enchondral ossification exerted a beneficial effect on repair. This relationship warrants consideration in future studies of cartilage injury and repair within the articular-epiphyseal cartilage complex of all species.
authors.affiliation: Equine Section, Department of Companion Animal Clinical Sciences, Norwegian School of Veterinary Science, Oslo, Norway.
authors.forename: Kristin
authors.initials: K
authors.lastname: Olstad
authors.affiliation: Equine Section, Department of Companion Animal Clinical Sciences, Norwegian School of Veterinary Science, Oslo, Norway.
authors.forename: Eli H S
authors.initials: EH
authors.lastname: Hendrickson
authors.affiliation: Division of Pathology, Department of Biomedicine and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Stina
authors.initials: S
authors.lastname: Ekman
authors.affiliation: Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, USA.
authors.forename: Cathy S
authors.initials: CS
authors.lastname: Carlson
authors.affiliation: Equine Section, Department of Companion Animal Clinical Sciences, Norwegian School of Veterinary Science, Oslo, Norway.
authors.forename: Nils I
authors.initials: NI
authors.lastname: Dolvik
keywords: articular–epiphyseal cartilage complex; cartilage incision; cartilage repair; enchondral ossification; histological examination