title: Effect of open wedge high tibial osteotomy on the lateral tibiofemoral compartment in sheep. Part II: standard and overcorrection do not cause articular cartilage degeneration.
abstract: OBJECTIVE
  To evaluate whether medial open wedge high tibial osteotomy (HTO) results in structural changes in the articular cartilage in the lateral tibiofemoral compartment of adult sheep.
  
  
  METHODS
  Three experimental groups received biplanar osteotomies of the right proximal tibiae: (a) closing wedge HTO (4.5° of tibial varus), (b) opening wedge HTO (4.5° tibial valgus; standard correction), and (c) opening wedge HTO (9.5° of valgus; overcorrection), each of which was compared to the contralateral knees that only received an arthrotomy. After 6 months, the macroscopic and microscopic characteristics of the articular cartilage of the lateral tibiofemoral compartment were assessed.
  
  
  RESULTS
  The articular cartilage in the central region of the lateral tibial plateau in sheep had a higher safranin O staining intensity and was 4.6-fold thicker than in the periphery (covered by the lateral meniscus). No topographical variation in the type-II collagen immunoreactivity was seen. All lateral tibial plateaus showed osteoarthritic changes in regions not covered by the lateral meniscus. No osteoarthritis was seen in the peripheral submeniscal regions of the lateral tibial plateau and the lateral femoral condyle. Opening wedge HTO resulting in both standard and overcorrection was not associated with significant macroscopic and microscopic structural changes between groups in the articular cartilage of the lateral tibial plateau and femoral condyle after 6 months in vivo.
  
  
  CONCLUSIONS
  Opening wedge HTO resulting in both standard and overcorrection is a safe procedure for the articular cartilage in an intact lateral tibiofemoral compartment of adult sheep at 6 months postoperatively.
authors: Center of Experimental Orthopaedics, Saarland University, Kirrbergerstr. 1, Bldg 37, 66421, Homburg, Saar, Germany.
authors: Raphaela
authors: R
authors: Ziegler
authors: Lars
authors: L
authors: Goebel
authors: Magali
authors: M
authors: Cucchiarini
authors: Dietrich
authors: D
authors: Pape
authors: Henning
authors: H
authors: Madry
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D017760:Bone Malalignment / Q000378:metabolism / Q000473:pathology; D005269:Femur / Q000601:surgery; D007150:Immunohistochemistry; D008592:Menisci, Tibial / Q000378:metabolism / Q000473:pathology*; D010027:Osteotomy / Q000379:methods*; D012756:Sheep; D034561:Sheep, Domestic; D013977:Tibia / Q000601:surgery*
chemical_list: D015415:Biomarkers