title: The effect of posterior cruciate ligament reconstruction on patellofemoral contact pressures in the knee joint under simulated muscle loads.
abstract: BACKGROUND
  The mechanism of cartilage degeneration in the patellofemoral joint (PFJ) and medial compartment of the knee following posterior cruciate ligament (PCL) injury remains unclear. PCL reconstruction has been recommended to restore kinematics and prevent long-term degeneration. The effect of current reconstruction techniques on PFJ contact pressures is unknown.
  
  
  OBJECTIVE
  To measure PFJ contact pressures after PCL deficiency and reconstruction.
  
  
  METHODS
  Eight cadaveric knees were tested with the PCL intact, deficient, and reconstructed. Contact pressures were measured at 30 degrees, 60 degrees, 90 degrees, and 120 degrees of flexion under simulated muscle loads. Knee kinematics were measured by a robotic testing system, and the PFJ contact pressures were measured using a thin film transducer. A single bundle achilles tendon allograft was used in the reconstruction.
  
  
  RESULTS
  PCL deficiency significantly increased the peak contact pressures measured in the PFJ relative to the intact knee under both an isolated quadriceps load of 400 N and a combined quadriceps/hamstrings load of 400 N/200 N. Reconstruction did not significantly reduce the increased contact pressures observed in the PCL-deficient knee.
  
  
  CONCLUSIONS
  The elevated contact pressures observed in the PCL-deficient knee and reconstructed knee might contribute to the long-term degeneration observed in both the non-operatively treated and PCL-reconstructed knees.
authors.affiliation: Orthopaedic Biomechanics Laboratory, Massachusetts General Hospital and Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Gill
authors.forename: Louis E
authors.initials: LE
authors.lastname: DeFrate
authors.forename: Conrad
authors.initials: C
authors.lastname: Wang
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Carey
authors.forename: Shay
authors.initials: S
authors.lastname: Zayontz
authors.forename: Bertram
authors.initials: B
authors.lastname: Zarins
authors.forename: Guoan
authors.initials: G
authors.lastname: Li
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D002102:Cadaver; D005269:Femur; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000503:physiopathology; D010329:Patella; D016119:Posterior Cruciate Ligament / Q000503:physiopathology / Q000601:surgery*; D011312:Pressure; D013314:Stress, Mechanical