title: Radiographic landmarks for locating the femoral origin and tibial insertion of the knee anterolateral ligament.
abstract: BACKGROUND
  Recent anatomic studies have confirmed the presence of a true ligament structure, the anterolateral ligament (ALL), in the anterolateral region of the knee. This structure is involved in the rotatory instability of the knee and might explain why some isolated reconstructions of the anterior cruciate ligament result in a residual pivot shift. Therefore, when considering the least invasive method for reconstruction of this structure, it is important to identify the corresponding bony landmarks on radiographic images.
  
  
  OBJECTIVE
  To establish radiographic femoral and tibial landmarks for the ALL in frontal and lateral views.
  
  
  METHODS
  Descriptive laboratory study.
  
  
  METHODS
  Ten unpaired cadaver knees were dissected. The attachments of the ALL were isolated and its anatomic parameters were quantified. Its origin and insertion were marked with a 2-mm-diameter metallic sphere, and radiographs were taken from frontal and lateral views. The obtained images were analyzed and the ALL parameters established.
  
  
  RESULTS
  The origin of the ALL in the lateral view was found at a point an average ± SD of 47.5% ± 4.3% from the anterior edge of the femoral condyle and about 3.7 ± 1.1 mm below the Blumensaat line. In the frontal view, the origin was about 15.8 ± 1.9 mm from the distal condyle line. The ALL insertion was an average of 53.2% ± 5.8% from the anterior edge of the lateral tibial plateau in the lateral view and 7.0 ± 0.5 mm below the lateral tibial plateau in the frontal view. In anatomic dissections, the origin of the ALL was 1.9 ± 1.4 mm anterior and 4.1 ± 1.1 mm distal to the lateral collateral ligament, and the insertion was 4.4 ± 0.8 mm below the lateral tibial plateau cartilage.
  
  
  CONCLUSIONS
  The ALL origin on an absolute lateral radiograph of the knee is approximately 47% of the anterior-posterior size of the condyle and 3.7 mm caudal to the Blumensaat line. In a frontal radiograph, the ALL is 15.8 mm from the posterior bicondyle line. The ALL insertion is approximately 53.2% of the anterior-posterior size of the plateau in the lateral view and 7.0 mm below the articular line in the frontal view.
  
  
  CONCLUSIONS
  Knowledge of the anatomic landmarks of the ALL on radiography will permit minimally invasive surgical reconstruction with lower morbidity.
authors.affiliation: 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 Camilo_helito@yahoo.com.br.
authors.forename: Camilo Partezani
authors.initials: CP
authors.lastname: Helito
authors.affiliation: 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
authors.affiliation: 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: 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: Luis Eduardo Passareli
authors.initials: LE
authors.lastname: Tirico
authors.affiliation: 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: 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: Jose Ricardo
authors.initials: JR
authors.lastname: Pecora
authors.affiliation: 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
mesh_terms: D000368:Aged; D059925:Anatomic Landmarks / Q000000981:diagnostic imaging*; D002102:Cadaver; D004210:Dissection; D005269:Femur / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D006801:Humans; D007719:Knee Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D008023:Ligaments, Articular / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D013977:Tibia / Q000033:anatomy & histology / Q000000981:diagnostic imaging*
keywords: anatomy; anterolateral ligament; radiography; rotatory instability