title: Intact bone vitality and increased accumulation of nonmineralized bone matrix in biopsy specimens of juvenile osteochondritis dissecans: a histological analysis.
abstract: BACKGROUND
  Although commonly proposed to be the starting point of juvenile osteochondritis dissecans (JOCD), avascular osteonecrosis (AVN) has been an inconsistent finding in histological studies. Analysis of early-stage lesions is required to elucidate the origins of OCD and justify proper treatment.
  
  
  OBJECTIVE
  To analyze histological sections of JOCD lesions with special emphasis on bone vitality.
  
  
  METHODS
  Cross-sectional study; Level of evidence, 3.
  
  
  METHODS
  Of 64 patients with 74 JOCD lesions (20 females, mean age, 11.4 years; 44 males, mean age, 12.7 years), 34 required surgery because of lesion instability or failed nonoperative treatment. From 9 patients, 11 histological specimens were obtained. Lesions were classified according to the International Cartilage Repair Society (ICRS). Two additional histological control sections were harvested from children without JOCD manifestation. Undecalcified histological sections were histomorphometrically analyzed. To analyze the skeletal health of the patients, biochemical analyses with special emphasis on bone metabolism were performed.
  
  
  RESULTS
  Histologically, no osteonecrosis was visible in any of the cases. Osteocyte distribution was similar among OCD lesions and controls. ICRS OCD I lesions (n = 6) showed no intralesional separation. In ICRS OCD II and III lesions (n = 5), there was a subchondral fracture concomitant with histological characteristics of active repair mechanism (increased bone formation: osteoid volume P = .008, osteoblast number P = .046; resorption: osteoclast number P = .005; and tissue fibrosis compared with controls). Instead, in ICRS OCD I lesions, subchondral osteoid volume (P = .010) and osteoblast number (P = .046) were significantly increased compared with controls; however, no active repair mechanisms (no increased bone resorption or fibrous tissue) were detected, suggesting a focal lack of mineralization. Fifty-seven of 64 patients (89.1%) showed a vitamin D deficiency. The median vitamin D serum level of the patients with ICRS OCD I lesions was 13.6 µg/L.
  
  
  CONCLUSIONS
  In the present study, osteonecrosis was not found in histological specimens of JOCD. As a secondary finding, focal accumulations of nonmineralized bone matrix indicating a lack of mineralization in ICRS OCD I lesions were revealed. This finding correlated with a low level of vitamin D in the affected children.
authors.affiliation: Department of Trauma and Reconstructive Surgery, Asklepios Clinic St Georg, Hamburg, Germany Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany matkrause@me.com.
authors.forename: Matthias
authors.initials: M
authors.lastname: Krause
authors.affiliation: Department of Pediatric Sports Medicine, Altona Childrens Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Lehmann
authors.affiliation: Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Amling
authors.affiliation: Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Tim
authors.initials: T
authors.lastname: Rolvien
authors.affiliation: Department of Trauma and Reconstructive Surgery, Asklepios Clinic St Georg, Hamburg, Germany.
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Frosch
authors.affiliation: Department of Legal Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Püschel
authors.affiliation: High Field MR Center, Department of Biochemical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria.
authors.forename: Klaus
authors.initials: K
authors.lastname: Bohndorf
authors.affiliation: Department of Trauma and Reconstructive Surgery, Asklepios Clinic St Georg, Hamburg, Germany Department of Pediatric Sports Medicine, Altona Childrens Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Norbert M
authors.initials: NM
authors.lastname: Meenen
mesh_terms: D000293:Adolescent; D001706:Biopsy; D001857:Bone Matrix / Q000473:pathology*; D001842:Bone and Bones / Q000473:pathology*; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D010008:Osteochondritis Dissecans / Q000473:pathology*
keywords: bone vitality; histology; osteochondritis dissecans; vitamin D deficiency