title: Patellofemoral contact area and pressure after medial patellofemoral ligament reconstruction.
abstract: BACKGROUND
  It is not known whether nonisometric femoral graft attachment diminishes the effectiveness of medial patellofemoral ligament reconstruction.
  
  
  OBJECTIVE
  To determine whether a nonisometric femoral attachment point is associated with differences in contact area and pressure in the patellofemoral joint as compared with an isometric attachment point.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Eleven cadaveric knees were amputated and secured in a loading fixture. The quadriceps tendon was clamped 5 cm above the proximal pole of the patella and fixed to a plate. Colinear compressive forces were applied. Forces were set to achieve isometric quadriceps moments at 30 degrees, 45 degrees, 60 degrees, and 90 degrees of knee flexion. Contact areas and pressures were measured using a sensor system. Initially, isometric reconstruction was done using the known isometric femoral attachment point of the posterior medial epicondyle. The attachment was then revised in each specimen to the known nonisometric femoral attachment of the adductor tubercle.
  
  
  RESULTS
  Before medial patellofemoral ligament reconstruction, average facet patellofemoral contact area and pressure generally increased with angle of knee flexion. With few exceptions, initial versus postprocedure data and isometric versus nonisometric contact area and pressure data did not differ significantly at any angle tested. Percentage contact area and contact pressure in the medial facet did not differ significantly from the initial percentage for either attachment, and no difference was found in the percentage medial contact area or pressure for isometric versus nonisometric attachment at the angles tested.
  
  
  CONCLUSIONS
  Use of the nonisometric attachment point of the adductor tubercle in medial patellofemoral ligament reconstruction did not appear to alter knee contact area or contact pressures as compared with isometric femoral attachment at the posterior medial epicondyle.
  
  
  CONCLUSIONS
  In medial patellofemoral ligament reconstruction, patellofemoral contact area and pressure may not be adversely affected by use of the nonisometric femoral attachment point used in this study.
authors.affiliation: Department of Orthopaedic Surgery, The Union Memorial Hospital, Baltimore, Maryland, USA.
authors.forename: Todd M
authors.initials: TM
authors.lastname: Melegari
authors.forename: Brent G
authors.initials: BG
authors.lastname: Parks
authors.forename: Leslie S
authors.initials: LS
authors.lastname: Matthews
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D005260:Female; D005269:Femur / Q000601:surgery; D006801:Humans; D007719:Knee Joint / Q000502:physiology / Q000601:surgery*; D008297:Male; D017888:Medial Collateral Ligament, Knee / Q000502:physiology / Q000601:surgery*; D008875:Middle Aged; D011184:Postoperative Period; D011312:Pressure; D013314:Stress, Mechanical; D013710:Tendons / Q000637:transplantation; D016474:Weight-Bearing / Q000502:physiology*