title: Why Do Authors Differ With Regard to the Femoral and Meniscal Anatomic Parameters of the Knee Anterolateral Ligament?: Dissection by Layers and a Description of Its Superficial and Deep Layers.
abstract: BACKGROUND
  No consensus exists regarding the anatomic characteristics of the knee anterolateral ligament (ALL). A critical analysis of the dissections described in previous studies allows the division of the ALL into 2 groups with similar characteristics. The presence of considerable variability suggests that the authors may not be referring to the same structure.
  
  
  OBJECTIVE
  To perform a lateral anatomic dissection, by layers, seeking to characterize the 2 variants described for the ALL on the same knee. We hypothesized that we would identify the 2 variants described for the ALL and that these variants would have distinct characteristics.
  
  
  METHODS
  Descriptive laboratory study.
  
  
  METHODS
  Thirteen unpaired cadaveric knees were used in this study. The dissection protocol followed the parameters described in previous studies. Immediately below the iliotibial tract, we isolated a structure designated as the superficial ALL, whereas between this structure and the articular capsule, we isolated a structure designated as the deep ALL. The 2 structures were measured for length at full extension and at 90° of flexion and for distance from the tibial insertion relative to the Gerdy tubercle. Potential contact with the lateral meniscus was also evaluated. After measurements were obtained, the 2 dissected structures underwent histologic analysis.
  
  
  RESULTS
  The superficial ALL presented a posterior and proximal origin to the center of the lateral epicondyle, its length increased on knee extension, and it exhibited no contact with the lateral meniscus. The deep ALL was located in the center of the lateral epicondyle, its length increased on knee flexion, and it presented a meniscal insertion. Both structures had a similar tibial insertion site; however, the insertion site of the deep ALL was located more posteriorly. The analysis of the histological sections for both structures indicated the presence of dense and well-organized collagen fibers.
  
  
  CONCLUSIONS
  This anatomic study clearly identified 2 structures, described as the superficial and deep ALL, which were consistent with previous but conflicting descriptions of the ALL.
  
  
  CONCLUSIONS
  This study clarifies numerous controversies encountered in anatomic studies of the ALL. Knowledge regarding the existence of 2 distinct structures in the anterolateral knee will allow more accurate evaluation of their functions and characteristics.
authors.affiliation: Knee Surgery Division, Department of Orthopaedics and Traumatology, Institute of Orthopedics and Traumatology-Hospital and Clinics, Faculty of Medicine, University of São Paulo (IOT-HCFMUSP), São Paulo, Brazil.
authors.forename: Camilo Partezani
authors.initials: CP
authors.lastname: Helito
authors.affiliation: Department of Orthopaedic Surgery, Catholic University of São Paulo, Sorocaba, São Paulo, Brazil.
authors.forename: Carlos
authors.initials: C
authors.lastname: do Amaral
authors.affiliation: Department of Orthopaedic Surgery, Catholic University of São Paulo, Sorocaba, São Paulo, Brazil.
authors.forename: Yuri da Cunha
authors.initials: YD
authors.lastname: Nakamichi
authors.affiliation: Knee Surgery Division, Department of Orthopaedics and Traumatology, Institute of Orthopedics and Traumatology-Hospital and Clinics, Faculty of Medicine, University of São Paulo (IOT-HCFMUSP), São Paulo, Brazil.
authors.forename: Riccardo Gomes
authors.initials: RG
authors.lastname: Gobbi
authors.affiliation: Knee Surgery Division, Department of Orthopaedics and Traumatology, Institute of Orthopedics and Traumatology-Hospital and Clinics, Faculty of Medicine, University of São Paulo (IOT-HCFMUSP), São Paulo, Brazil.
authors.forename: Marcelo Batista
authors.initials: MB
authors.lastname: Bonadio
authors.affiliation: Knee Surgery Division, Department of Orthopaedics and Traumatology, Institute of Orthopedics and Traumatology-Hospital and Clinics, Faculty of Medicine, University of São Paulo (IOT-HCFMUSP), São Paulo, Brazil.
authors.forename: Renato José Mendonça
authors.initials: RJ
authors.lastname: Natalino
authors.affiliation: Knee Surgery Division, Department of Orthopaedics and Traumatology, Institute of Orthopedics and Traumatology-Hospital and Clinics, Faculty of Medicine, University of São Paulo (IOT-HCFMUSP), São Paulo, Brazil.
authors.forename: José Ricardo
authors.initials: JR
authors.lastname: Pécora
authors.affiliation: Department of Orthopaedic Surgery, Catholic University of São Paulo, Sorocaba, São Paulo, Brazil.
authors.forename: Tulio Pereira
authors.initials: TP
authors.lastname: Cardoso
authors.affiliation: Knee Surgery Division, Department of Orthopaedics and Traumatology, Institute of Orthopedics and Traumatology-Hospital and Clinics, Faculty of Medicine, University of São Paulo (IOT-HCFMUSP), São Paulo, Brazil.
authors.forename: Gilberto Luis
authors.initials: GL
authors.lastname: Camanho
authors.affiliation: Knee Surgery Division, Department of Orthopaedics and Traumatology, Institute of Orthopedics and Traumatology-Hospital and Clinics, Faculty of Medicine, University of São Paulo (IOT-HCFMUSP), São Paulo, Brazil.
authors.forename: Marco Kawamura
authors.initials: MK
authors.lastname: Demange
keywords: anatomy; anterolateral instability; anterolateral ligament; histology; knee