title: Osteochondral microdamage from valgus bending of the human knee.
abstract: BACKGROUND
  Valgus bending of the knee is promoted as an anterior cruciate ligament injury mechanism and is associated with a characteristic "footprint" of bone bruising. The hypothesis of this study was that during ligamentous failure caused by valgus bending of the knee, high tibiofemoral contact pressures induce acute osteochondral microdamage.
  
  
  METHODS
  Four knee pairs were loaded in valgus bending until gross injury with or without a tibiofemoral compression pre-load. The peak valgus moment and resultant motions of the knee joint were recorded. Pressure sensitive film documented the magnitude and location of tibiofemoral contact. Cartilage fissures were documented on the tibial plateau, and microcracks in subchondral bone were documented from micro-computed tomography scans.
  
  
  RESULTS
  Injuries were to the anterior cruciate ligament in three knees and the medial collateral ligament in seven knees. The mean (standard deviation) peak bending moment at failure was 107 (64)Nm. Valgus bending produced regions of contact on the lateral tibial plateau with average maximum pressures of approximately 30 (8)MPa. Cartilage fissures and subchondral bone microcracks were observed in these regions of high contact pressure.
  
  
  CONCLUSIONS
  Combined valgus bending and tibiofemoral compression produce slightly higher contact pressures, but do not alter the gross injury pattern from isolated valgus bending experiments. Athletes who sustain a severe valgus knee bending moment, may be at risk of acute osteochondral damage especially if the loading mechanism occurs with a significant tibiofemoral compression component.
authors.affiliation: Orthopaedic Biomechanics Laboratories, College of Osteopathic Medicine, Michigan State University, A407 East Fee Hall, East Lansing, MI 48824, USA.
authors.forename: Eric G
authors.initials: EG
authors.lastname: Meyer
authors.forename: Mark R
authors.initials: MR
authors.lastname: Villwock
authors.forename: Roger C
authors.initials: RC
authors.lastname: Haut
mesh_terms: D000328:Adult; D002102:Cadaver; D019245:Compressive Strength; D050724:Fractures, Cartilage / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D007718:Knee Injuries / Q000000981:diagnostic imaging / Q000503:physiopathology*; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D011312:Pressure; D011859:Radiography; D012421:Rupture / Q000000981:diagnostic imaging / Q000503:physiopathology; D013978:Tibial Fractures / Q000000981:diagnostic imaging / Q000503:physiopathology*; D019415:Torque; D016474:Weight-Bearing