title: Bone screws have advantages in repair of experimental osteochondral fragments.
abstract: BACKGROUND
  Cartilage defects are created on intraarticular osteochondral fragments at the entrance holes of fixation devices when these fragments are fixed to the original sites. Conventional fixation devices hinder repair of these defects and there is a latent risk of secondary osteoarthritis. We therefore developed a novel fixation device system consisting of bone screws made of cortical bone for osteochondral fragments to improve repair of these surface defects.
  
  
  OBJECTIVE
  We asked whether bone screws had advantages over poly-L-lactic acid (PLLA) screws in terms of (1) gross assessment of the surface, (2) volume and histologic quality of the repair tissue, and (3) biomechanical assessment of the tissue stiffness.
  
  
  METHODS
  We examined gross morphology, microCT, histology, and stiffness of the repaired tissue with PLLA (n = 32) and bone (n = 32) screws in a rabbit model of osteochondral fracture, compared with normal controls (n = 16).
  
  
  RESULTS
  Gross morphology and histology revealed better quality with bone screws than with PLLA screws. Mean repaired volumes in microCT were 70.6% ± 14% with bone screws and 50.3% ± 15% with PLLA screws. Average stiffness values for PLLA screws, bone screws, and normal cartilage were 1.67 ± 0.54 N/mm, 2.63 ± 0.42 N/mm, and 3.15 ± 0.49 N/mm, respectively.
  
  
  CONCLUSIONS
  Our results show better repaired tissue was observed for quality and quantity when chondral fractures were treated with bone screws than when treated with PLLA screws.
  
  
  CONCLUSIONS
  Bone screws made of cortical bone may have applications in clinical situations for the fixation of intraarticular osteochondral fragments.
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, Shimane University, Izumo, Shimane, 693-8501, Japan. mkono@med.shimane-u.ac.jp
authors.forename: Michihaya
authors.initials: M
authors.lastname: Kono
authors.forename: Ryuji
authors.initials: R
authors.lastname: Mori
authors.forename: Yuji
authors.initials: Y
authors.lastname: Uchio
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001861:Bone Regeneration; D001863:Bone Screws; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D002417:Cattle; D004195:Disease Models, Animal; D005269:Femur / Q000637:transplantation*; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D017102:Fracture Healing; D050723:Fractures, Bone / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D019344:Lactic Acid; D008297:Male; D016348:Osseointegration; D010329:Patella / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D011091:Polyesters; D011108:Polymers; D011474:Prosthesis Design; D011817:Rabbits; D055114:X-Ray Microtomography
chemical_list: D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide)
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