title: BIOMECHANICAL ACCESS METHOD FOR ANALYZING ISOMETRICITY IN RECONSTRUCTING THE MEDIAL PATELLOFEMORAL LIGAMENT.
abstract: OBJECTIVE
  To present a biomechanical device for evaluating medial patellofemoral ligament (MPFL) reconstruction and its isometricity.
  
  
  METHODS
  An accessible biomechanical method that allowed application of physiological and non-physiological forces to the knee using a mechanical arm and application of weights and counterweights was developed, so as to enable many different evaluations and have a very accurate measurement system for distances between different structures, for analysis on experiments. This article describes the assembly of this system, and suggests some practical applications. Six cadaver knees were studied. The knees were prepared in a testing machine developed at the Biomechanics Laboratory of IOT-HCFMUSP, which allowed dynamic evaluation of patellar behavior, with quantification of patellar lateralization between 0° and 120°. The differences between the distances found with and without load applied to the patella were grouped according to the graft fixation angle (0°, 30°, 60° or 90°) and knee position (intact, damaged or reconstructed).
  
  
  RESULTS
  There was a tendency for smaller lateral displacement to occur at fixation angles greater than 30 degrees of flexion, especially between the angles of 45° and 60° degrees of flexion, after the reconstruction. For the other angles, there was no statistical significance.
  
  
  CONCLUSIONS
  The method developed is a useful tool for studies on the patellofemoral joint and the MPFL, and has a very accurate measurement system for distances between different structures. It can be used in institutions with fewer resources available.
authors.affiliation: MSc from the Institute of Orthopedics and Traumatology, Hospital das Clínicas, School of Medicine, University of São Paulo, São Paulo, SP, Brazil.
authors.forename: David
authors.initials: D
authors.lastname: Sadigursky
authors.affiliation: Attending Physician in the Knee Group, Institute of Orthopedics and Traumatology, Hospital das Clínicas, School of Medicine, University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Riccardo Gomes
authors.initials: RG
authors.lastname: Gobbi
authors.affiliation: Technologist in the Biomechanics Laboratory, Institute of Orthopedics and Traumatology, Hospital das Clínicas, School of Medicine, University of São Paulo, São Paulo, SP, Brazil.
authors.forename: César Augusto Martins
authors.initials: CA
authors.lastname: Pereira
authors.affiliation: PhD in Sciences and Head of the Knee Group, Institute of Orthopedics and Traumatology, Hospital das Clínicas, School of Medicine, University of São Paulo, São Paulo, SP, Brazil.
authors.forename: José Ricardo
authors.initials: JR
authors.lastname: Pécora
authors.affiliation: Titular Professor and Head of the Department of Orthopedics and Traumatology, School of Medicine, University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Gilberto Luis
authors.initials: GL
authors.lastname: Camanho
keywords: Biomechanics; Joint Instability; Knee/surgery; Patellar Ligament