title: Vasculature deprivation-induced osteonecrosis of rats' femoral heads associated with the formation of deep surface depressions.
abstract: BACKGROUND
  Shallow or deep bowl-shaped depressions often develop after drilling an intraosseous conduit in the necrotic, avascular femoral head of rats. The etiopathogenesis of tissue loss at the articulation surface after a drilling procedure was elaborated in the authors' previous reports.
  
  
  OBJECTIVE
  To scrutinize a large collection of femoral heads of rats in order to search for similar changes in cases in which no drilling procedure was carried out.
  
  
  METHODS
  This retrospective study comprised the specimens of 386 rats with vessels-deprived osteonecrosis of the femoral heads, none of the animals having undergone a drilling procedure.
  
  
  RESULTS
  Shallow or deep bowl-shaped depressions were encountered at an incidence as low as 2.8% of the femoral heads of the above mentioned 386 rats. It is not feasible to distinguish histologically the "spontaneously" arising from and drilling-related depressions.
  
  
  CONCLUSIONS
  No assured explanation can be offered for the evolving depressions of the surface of femoral heads of rats, which have not undergone a drilling procedure. It is hypothesized that the synovial fluid forces its way via slits in the articulation surface and bores cavities in the substance of femoral heads, which display a postosteonecrotic osteoarthritis-like disorder. The rising pressure in the arthritic joints results, firstly, in an enlargement of these cavities and, secondly, loss of fibro-cartilaginous tissue such that the cavities come to communicate with the articular space.
authors.affiliation: Department of Orthopaedic Surgery B, Rambam Health Care Campus and The Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, P. O. Box 9602, Haifa, Israel 31096. e_peled@rambam.health.gov.il
authors.forename: Eli
authors.initials: E
authors.lastname: Peled
authors.forename: Jacob
authors.initials: J
authors.lastname: Bejar
authors.forename: Chaim
authors.initials: C
authors.lastname: Zinman
authors.forename: Jochanan H
authors.initials: JH
authors.lastname: Boss
mesh_terms: D000818:Animals; D016723:Bone Remodeling; D004195:Disease Models, Animal; D005260:Female; D005270:Femur Head / Q000098:blood supply* / Q000473:pathology*; D005271:Femur Head Necrosis / Q000473:pathology*; D009389:Neovascularization, Pathologic; D010012:Osteogenesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D012189:Retrospective Studies