title: The effect of experimental cartilage damage and impairment and restoration of synovial lubrication on friction in the temporomandibular joint.
abstract: OBJECTIVE
  To evaluate how the frictional coefficient of the porcine temporomandibular joint (TMJ) is affected by an impairment of the synovial lubrication produced by an experimental abrasion of the articular cartilage and the application of hyaluronic acid (HA) with different molecular weights to the abraded cartilage surfaces.
  
  
  METHODS
  Erosion of the articular cartilage was produced by scouring it with sandpaper. Impairment and restoration of synovial lubrication were modeled by washing the joint space with phosphate-buffered saline (PBS) and by the application of HA with different molecular weights. After measuring the frictional coefficients in the intact TMJs (n = 10), the effects of washing with PBS, sandpaper scouring, and the application of HA were subsequently examined.
  
  
  RESULTS
  The mean frictional coefficient in the intact joint was 0.0154 (SD 0.0043). After PBS washing and sandpaper scouring, it increased significantly to 0.0235 (SD 0.0052) and 0.0520 (SD 0.0088), respectively. Subsequent application of HA resulted in a significant decrease (43% to 56%) of the frictional coefficient. Observations by scanning electron microscopy showed that after sandpaper scouring, the superficial cartilage layer was disrupted and inner layer was exposed, creating an irregular surface.
  
  
  CONCLUSIONS
  Joint friction may increase by approximately 350% following an experimental scouring of the cartilage surface and impairment of synovial lubrication. Lubrication by means of HA decreased joint friction by approximately 50%.
authors.affiliation: Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan. etanaka@hiroshima-u.ac.jp
authors.forename: Eiji
authors.initials: E
authors.lastname: Tanaka
authors.forename: Tatsunori
authors.initials: T
authors.lastname: Iwabe
authors.forename: Diego A
authors.initials: DA
authors.lastname: Dalla-Bona
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Kawai
authors.forename: Theo
authors.initials: T
authors.lastname: van Eijden
authors.forename: Masao
authors.initials: M
authors.lastname: Tanaka
authors.forename: Shoji
authors.initials: S
authors.lastname: Kitagawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Takata
authors.forename: Kazuo
authors.initials: K
authors.lastname: Tanne
mesh_terms: D000818:Animals; D017276:Friction; D006820:Hyaluronic Acid / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D008153:Lubrication; D008970:Molecular Weight; D013552:Swine; D013582:Synovial Fluid / Q000502:physiology*; D013704:Temporomandibular Joint / Q000187:drug effects; D019224:Temporomandibular Joint Disc / Q000293:injuries*; D013705:Temporomandibular Joint Disorders / Q000188:drug therapy*
chemical_list: D006820:Hyaluronic Acid