title: In vitro investigation of the effect of medial patellofemoral ligament reconstruction and medial tibial tuberosity transfer on lateral patellar stability.
abstract: OBJECTIVE
  Two different operative techniques for stabilizing the patella against lateral displacement movement were investigated.
  
  
  METHODS
  In vitro experimental study.
  
  
  METHODS
  Five human cadaver knee specimens with a normal Q-angle were mounted in a kinematic knee simulator and investigated under simulated isokinetic extension motions. Patellar movement was measured while a 100-N laterally directed subluxation load was applied to the patella. Ligament loading of the medial patellofemoral ligament was measured using a strain gauge based buckle transducer inserted in the fibers of the ligament. The knee was evaluated in an intact physiologic state, as well as after medial transfer of the tibial tuberosity, and after the medial patellofemoral ligament was transected and reconstructed using a hamstring autograft.
  
  
  RESULTS
  A significant reduction in lateral displacement and ligament load was observed with the use of the hamstring autograft reconstruction compared with the medial transfer of the tibial tuberosity.
  
  
  CONCLUSIONS
  Medial transfer of the tibial tuberosity showed no significant relief of ligament loading and stabilizing effect on patellar movement, whereas reconstruction of the medial patellofemoral ligament showed a significant stabilizing effect on patellar movement.
  
  
  CONCLUSIONS
  In cadaver specimens, we evaluated the effect of tibial tubercle transfer and the patellofemoral ligament and found that reconstruction of the patellofemoral ligament alone was sufficient to restore stability in a cadaveric model. Additionally, we found that the flexion angle had little effect on the loading of the medial patellofemoral ligament autograft, which would support early mobilization of patients after surgery. We found that the graft was not unduly loaded.
authors.affiliation: Department of Orthopaedics, Hannover Medical School, Hannover, Germany. sven.ostermeier@annastift.de
authors.forename: Sven
authors.initials: S
authors.lastname: Ostermeier
authors.forename: Christina
authors.initials: C
authors.lastname: Stukenborg-Colsman
authors.forename: Christof
authors.initials: C
authors.lastname: Hurschler
authors.forename: Carl-Joachim
authors.initials: CJ
authors.lastname: Wirth
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena / Q000295:instrumentation; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007593:Joint Instability / Q000601:surgery; D008297:Male; D008875:Middle Aged; D031222:Patellar Dislocation / Q000601:surgery*; D017847:Patellar Ligament / Q000601:surgery*; D013314:Stress, Mechanical; D013710:Tendons / Q000637:transplantation; D013977:Tibia / Q000637:transplantation*; D014182:Transplantation, Autologous; D016474:Weight-Bearing