title: Effect of tibial tubercle elevation on biomechanics of the entire knee joint under muscle loads.
abstract: BACKGROUND
  Anterior elevation of the tibial tubercle, known as Maquet procedure, is performed to reduce excessive patellofemoral contact stresses in knee joints with patellofemoral osteoarthritis and anterior pain. Previous investigations, however, have entirely focused on the likely effect of tibial tubercle elevation procedure on biomechanics of contact at the patellofemoral joint with no attention what-so-ever to associated alterations in biomechanics of the tibiofemoral joint.
  
  
  METHODS
  Using a validated 3D nonlinear finite element model of the entire knee joint, the effect of 1.25 cm and 2.5 cm tubercle elevations on the entire knee joint biomechanics was investigated under constant quadriceps load of 411 N alone or combined with hamstrings co-activation of 205.5 N under joint angles of 0-90 degrees.
  
  
  RESULTS
  Results confirm the effectiveness of this procedure in reducing patellofemoral contact forces, especially at smaller flexion angles. Maximum contact stress substantially decreased at full extension but increased at 90 degrees. Substantial effects of tuberosity elevation on tibial kinematics, cruciate ligament forces, tibiofemoral contact forces and extensor lever arm were found. The posterior cruciate ligament and tibiofemoral contact forces at larger flexion angles considerably increased whereas the anterior cruciate ligament and tibiofemoral contact forces at near full extension angles decreased. Overall, the extent of changes depended on the magnitude of anterior elevation, joint flexion angle and loading considered.
  
  
  CONCLUSIONS
  Biomechanics of the tibiofemoral joint were significantly influenced by tibial tubercle elevation. Current results advocate the need for an integral view of the entire knee joint in management of various joint disorders rather than a view in which each component is considered and treated in isolation with no due attention to perturbations caused and associated consequences.
authors.affiliation: Department of Mechanical Engineering, Ecole Polytechnique, P.O. Box 6079, Station centre-ville, Montréal, Québec, Canada H3C 3A7. abshir@meca.polymtl.ca
authors.forename: A
authors.initials: A
authors.lastname: Shirazi-Adl
authors.forename: W
authors.initials: W
authors.lastname: Mesfar
mesh_terms: D001696:Biomechanical Phenomena; D020342:Finite Element Analysis; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology*; D020370:Osteoarthritis, Knee / Q000503:physiopathology*; D046788:Patellofemoral Pain Syndrome / Q000503:physiopathology; D013314:Stress, Mechanical