title: Topographic variations in biomechanical and biochemical properties in the ankle joint: an in vitro bovine study evaluating native and engineered cartilage.
abstract: OBJECTIVE
  The purposes of this study were to identify differences in the biomechanical and biochemical properties among the articulating surfaces of the ankle joint and to evaluate the functional and biological properties of engineered neocartilage generated using chondrocytes from different locations in the ankle joint.
  
  
  METHODS
  The properties of the different topographies within the ankle joint (tibial plafond, talar dome, and distal fibula) were evaluated in 28 specimens using 7 bovine ankles; the femoral condyle was used as a control. Chondrocytes from the same locations were used to form 28 neocartilage constructs by tissue engineering using an additional 7 bovine ankles. The functional properties of neocartilage were compared with native tissue values.
  
  
  RESULTS
  Articular cartilage from the tibial plafond, distal fibula, talar dome, and femoral condyle exhibited Young modulus values of 4.8 ± 0.5 MPa, 3.9 ± 0.1 MPa, 1.7 ± 0.2 MPa, and 4.0 ± 0.5 MPa, respectively. The compressive properties of the corresponding tissues were 370 ± 22 kPa, 242 ± 18 kPa, 255 ± 26 kPa, and 274 ± 18 kPa, respectively. The tibial plafond exhibited 3-fold higher tensile properties and 2-fold higher compressive and shear moduli compared with its articulating talar dome; the same disparity was observed in neocartilage. Similar trends were detected in biochemical data for both native and engineered tissues.
  
  
  CONCLUSIONS
  The cartilage properties of the various topographic locations within the ankle are significantly different. In particular, the opposing articulating surfaces of the ankle have significantly different biomechanical and biochemical properties. The disparity between tibial plafond and talar dome cartilage and chondrocytes warrants further evaluation in clinical studies to evaluate their exact role in the pathogenesis of ankle lesions.
  
  
  CONCLUSIONS
  Therapeutic modalities for cartilage lesions need to consider the exact topographic source of the cells or cartilage grafts used. Furthermore, the capacity of generating neocartilage implants from location-specific chondrocytes of the ankle joint may be used in the future as a tool for the treatment of chondral lesions.
authors: Department of Biomedical Engineering, University of California, Davis, California, U.S.A.; Orthopaedic Sports Medicine Center of Ioannina, Department of Orthopaedic Surgery, University of Ioannina, Ioannina, Greece.
authors: Nikolaos K
authors: NK
authors: Paschos
authors: Department of Biomedical Engineering, University of California, Davis, California, U.S.A.; Department of Orthopedic Surgery and Musculoskeletal Trauma, University of Thessaly, Larisa, Greece.
authors: Eleftherios A
authors: EA
authors: Makris
authors: Department of Biomedical Engineering, University of California, Davis, California, U.S.A.
authors: Jerry C
authors: JC
authors: Hu
authors: Department of Biomedical Engineering, University of California, Davis, California, U.S.A.; Department of Orthopaedic Surgery, Lawrence Ellison Center for Tissue Regeneration and Repair, School of Medicine, University of California, Davis, California, U.S.A.. Electronic address: athanasiou@ucdavis.edu.
authors: Kyriacos A
authors: KA
authors: Athanasiou
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D000843:Ankle Joint / Q000737:chemistry / Q000502:physiology*; D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000737:chemistry / Q000502:physiology*; D002417:Cattle; D019902:Chondrocytes / Q000637:transplantation; D002851:Chromatography, High Pressure Liquid; D003094:Collagen / Q000032:analysis; D055119:Elastic Modulus / Q000502:physiology; D005269:Femur / Q000737:chemistry / Q000502:physiology; D005360:Fibula / Q000737:chemistry / Q000502:physiology; D006025:Glycosaminoglycans / Q000032:analysis; D066298:In Vitro Techniques; D013628:Talus / Q000737:chemistry / Q000502:physiology; D013977:Tibia / Q000737:chemistry / Q000502:physiology; D023822:Tissue Engineering
chemical_list: D000596:Amino Acids; D006025:Glycosaminoglycans; C013786:A73025; C015484:pyridinoline; D003094:Collagen