title: Biomechanical evaluation of medial patello-femoral ligament reconstruction: comparison between a double-bundle converging tunnels technique versus a single-bundle technique.
abstract: BACKGROUND
  Several MPFL reconstructions are commonly performed for recurrent patellar dislocation, but misleading data are currently available in the literature on the ability of the different techniques to re-create a functioning ligament.
  
  
  METHODS
  In this study, we showed the biomechanical properties of two different procedures for MPFL reconstruction using a natural orientation during uniaxial tensile testing. Eighteen fresh-frozen human knees were randomly assigned to two groups of nine each. In the group A, the reconstruction was performed using a double converging tunnels technique and in the group B was used a single-tunnel technique with semitendinosus autograft. The specimens were loaded in natural orientation using an Instron tensile test machine, and the stiffness and ultimate load were determined.
  
  
  RESULTS
  The ultimate load was 213 ± 90 and 171 ± 51 N using our double-bundle technique (group A) and the single-bundle technique (group B), respectively. One (11 %) specimen failed at the patellar side due to patellar fracture in the group B. There was no statistical significant difference (p > 0.05) between the two groups in terms of stiffness and ultimate load.
  
  
  CONCLUSIONS
  This study is the first biomechanical evaluation of the MPFL reconstructions in natural orientation. Both the procedures achieved safe fixation of the graft at the femoral attachment; however, the single-bundle technique reported 11 % of failure at the patellar side due to patellar fracture. In addition, the double-bundle technique can better restore the anatomy of the native ligament.
authors.affiliation: Fondazione Policlinico Agostino Gemelli, Istituto di Clinica Ortopedica e Traumatologica, Università Cattolica del Sacro Cuore di Roma, Largo Agostino Gemelli, 1 Policlinico Gemelli di Roma, 00135, Rome, Italy. giacomo.placella@gmail.com.
authors.forename: G
authors.initials: G
authors.lastname: Placella
authors.affiliation: Fondazione Policlinico Agostino Gemelli, Istituto di Clinica Ortopedica e Traumatologica, Università Cattolica del Sacro Cuore di Roma, Largo Agostino Gemelli, 1 Policlinico Gemelli di Roma, 00135, Rome, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Speziali
authors.affiliation: Ospedale S. Maria della Misericordia, Clinica Ortopedica e Traumatologica, Univesità degli Studi di Perugia, Perugia, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Sebastiani
authors.affiliation: Policlinico P. Giaccone, Clinica Ortopedica e Traumatologica, Univerità degli Studi di Palermo, Palermo, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Morello
authors.affiliation: Fondazione Policlinico Agostino Gemelli, Istituto di Clinica Ortopedica e Traumatologica, Università Cattolica del Sacro Cuore di Roma, Largo Agostino Gemelli, 1 Policlinico Gemelli di Roma, 00135, Rome, Italy.
authors.forename: M M
authors.initials: MM
authors.lastname: Tei
authors.affiliation: Fondazione Policlinico Agostino Gemelli, Istituto di Clinica Ortopedica e Traumatologica, Università Cattolica del Sacro Cuore di Roma, Largo Agostino Gemelli, 1 Policlinico Gemelli di Roma, 00135, Rome, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Cerulli
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D002102:Cadaver; D000070632:Hamstring Tendons / Q000601:surgery*; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology / Q000601:surgery*; D008023:Ligaments, Articular / Q000503:physiopathology / Q000601:surgery*; D031222:Patellar Dislocation / Q000503:physiopathology / Q000601:surgery*; D057071:Patellofemoral Joint / Q000503:physiopathology / Q000601:surgery*; D011897:Random Allocation; D019651:Plastic Surgery Procedures / Q000379:methods*; D013718:Tensile Strength; D014182:Transplantation, Autologous; D016474:Weight-Bearing
keywords: Biomechanics; MPFL reconstruction; Specimen orientation