title: Tibiofemoral loss of contact area but no changes in peak pressures after meniscectomy in a Lapine in vivo quadriceps force transfer model.
abstract: OBJECTIVE
  The menisci are thought to modulate load transfer and to absorb shocks in the knee joint. No study has experimentally measured the meniscal functions in the intact, in vivo joint loaded by physiologically relevant muscular contractions.
  
  
  METHODS
  Right knee joints of seven New Zealand white rabbits were loaded using isometric contractions of the quadriceps femoris muscles controlled by femoral nerve stimulation. Isometric knee extensor torques at the maximal and two submaximal force levels were performed at knee angles of 70°, 90°, 110°, and 130°. Patellofemoral and tibiofemoral contact areas and pressure distributions were measured using Fuji Presensor film inserted above and below the menisci and also with the menisci removed.
  
  
  RESULTS
  Meniscectomy was associated with a decrease in tibiofemoral contact area ranging from 30 to 70% and a corresponding increase in average contact pressures. Contact areas measured below the menisci were consistently larger than those measured on top of the menisci. Contact areas in the patellofemoral joint (PFJ), and peak pressures in tibiofemoral and PFJs, were not affected by meniscectomy. Contact areas and peak pressures in all joints depended crucially on knee joint angle and quadriceps force: The more flexed the knee joint was, the larger were the contact areas and the higher were the peak pressures.
  
  
  CONCLUSIONS
  In agreement with the literature, removal of the menisci was associated with significant decreases in tibiofemoral contact area and corresponding increases in average contact pressures, but surprisingly, peak pressures remained unaffected, indicating that the function of the menisci is to distribute loads across a greater contact area.
authors.affiliation: Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB, T2N 1N4, Canada, aleumann@uhbs.ch.
authors.forename: Andre
authors.initials: A
authors.lastname: Leumann
authors.forename: Rafael
authors.initials: R
authors.lastname: Fortuna
authors.forename: Tim
authors.initials: T
authors.lastname: Leonard
authors.forename: Victor
authors.initials: V
authors.lastname: Valderrabano
authors.forename: Walter
authors.initials: W
authors.lastname: Herzog
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D005260:Female; D005269:Femur / Q000502:physiology; D007537:Isometric Contraction; D007719:Knee Joint / Q000502:physiology* / Q000601:surgery; D008592:Menisci, Tibial / Q000502:physiology* / Q000601:surgery; D023421:Models, Animal; D057071:Patellofemoral Joint / Q000502:physiology / Q000601:surgery; D011312:Pressure; D052097:Quadriceps Muscle / Q000502:physiology; D011817:Rabbits; D013977:Tibia / Q000502:physiology