title: Biomechanical evaluation of MPFL reconstructions: differences in dynamic contact pressure between gracilis and fascia lata graft.
abstract: OBJECTIVE
  To evaluate the knee kinematics of the intact, MPFL-ruptured and MPFL-reconstructed knee and, moreover, to compare dynamic patellofemoral contact pressure of the gracilis tendon and the fascia lata as an alternative graft option for reconstruction of the MPFL.
  
  
  METHODS
  Eight paired human cadaveric knees were fixed in a custom-made fixation device. Patellofemoral contact pressure was assessed during a dynamic flexion movement at 15°-30°-45°-60°-75° and 90° using a pressure-sensitive film (Tekscan). The medial patellofemoral ligament was cut, and measurements were repeated. Finally, reconstruction of the MPFL was performed using the gracilis tendon (group I) or a fascia lata graft (group II). Tunnel localization was performed under fluoroscopic control. Grafts were fixed at 30° of flexion, and pressure measurements were repeated.
  
  
  RESULTS
  Incision of the medial patellofemoral ligament significantly reduced patellofemoral contact pressure at 15°, 30° and 45° of knee flexion compared to the intact knee (p < 0.05), whereas reconstruction of the MPFL using either gracilis tendon of the fascia lata was able to restore pressure distributions at 15° and 30° of knee flexion. However, in the hamstring group, reconstruction of the MPFL revealed a significantly reduced contact pressure at 45° of flexion (p = 0.038) compared to the intact knee. In the fascia lata group, a significant reduction in patellofemoral contact pressure was observed after MPFL reconstruction at 45°, 60°, 75° and 90° of knee flexion (p < 0.05).
  
  
  CONCLUSIONS
  Anatomic reconstruction of the MPFL with either a gracilis or a fascia lata graft showed comparable patellofemoral pressure distributions which were closely restored compared to the native knee. Therefore, the fascia lata has shown to be a viable alternative to the gracilis tendon for reconstruction of the MPFL. However, anatomic reconstruction of the MPFL may lead to persistently altered patellofemoral contact pressure during knee flexion compared to the native knee independent of the tested graft.
authors.affiliation: Department of Orthopaedic Surgery, Saarland University, Kirrberger Str, Geb. 37, 66421, Homburg (Saar), Germany. olaf.lorbach@gmx.de.
authors.forename: Olaf
authors.initials: O
authors.lastname: Lorbach
authors.affiliation: Department of Orthopaedic Surgery, Saarland University, Kirrberger Str, Geb. 37, 66421, Homburg (Saar), Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Haupert
authors.affiliation: Department of Orthopaedic Surgery, Marburg University, Marburg, Germany.
authors.forename: Turgay
authors.initials: T
authors.lastname: Efe
authors.affiliation: Department of Trauma-Hand and Reconstructive Surgery, Saarland University, Homburg (Saar), Germany.
authors.forename: Antonius
authors.initials: A
authors.lastname: Pizanis
authors.affiliation: Institute of Anatomy, Lübeck University, Lübeck, Germany.
authors.forename: Imke
authors.initials: I
authors.lastname: Weyers
authors.affiliation: Department of Orthopaedic Surgery, Saarland University, Kirrberger Str, Geb. 37, 66421, Homburg (Saar), Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Kohn
authors.affiliation: Department of Orthopaedic and Trauma Surgery, Klinikum Ernst von Bergmann, Potsdam/Bad Belzig, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Kieb
mesh_terms: D001696:Biomechanical Phenomena; D002102:Cadaver; D005206:Fascia Lata / Q000637:transplantation*; D005471:Fluoroscopy; D000071976:Gracilis Muscle / Q000601:surgery*; D000070633:Hamstring Muscles; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology / Q000601:surgery; D008023:Ligaments, Articular / Q000503:physiopathology / Q000601:surgery*; D057071:Patellofemoral Joint / Q000503:physiopathology / Q000601:surgery*; D011312:Pressure; D016059:Range of Motion, Articular; D019651:Plastic Surgery Procedures; D013710:Tendons / Q000637:transplantation*
keywords: Biomechanical; Knee kinematics; MPFL; Patella; Patellofemoral
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