title: ANATOMIC STUDY OF THE PROXIMAL THIRD OF THE FEMUR: FEMOROACETABULAR IMPACT AND THE CAM EFFECT.
abstract: To analyze anatomical variations of the proximal end of femur that could cause a femoroacetabular impact.
  
  
  METHODS
  199 skeletically mature anatomical specimens of femurs were used. The femurs were measured in order to determine the anteversion angle of the femoral neck, neckshaft angle, sphericity of the femoral head at anteroposterior and superoinferior, angle between epiphysis and the anterior femoral neck, angle between epiphysis and the neck at lateral plane, anteroposterior distance at 5mm of the head and neck junction and anteroposterior distance of the neck base.
  
  
  RESULTS
  we found that the impact subgroup presented a significantly larger junction diameter of 5mm (p = 0.0001) and cam-head (%) (p= 0.0001), while base-cam (%) (p = 0.0001) showed a significantly smaller diameter than the subgroup without impact. It was identified that cam-head (%) ≤ 80 e base-cam (%) ≤ 73 were identified as the optimal impact points.
  
  
  CONCLUSIONS
  our study showed that the effect cam, caused by anatomical variations of the proximal femoral end focused the head-neck junction and base of the neck-junction head-neck. These rates can be predictive factors of the impact.
authors.affiliation: Universidade Federal de São Paulo, Escola Paulista de Medicina; Dr. Donato D'Angelo's Orthopedics and Traumatology Clinic, Hospital Santa Teresa, Petrópolis, RJ, Brazil.
authors.forename: Pedro José
authors.initials: PJ
authors.lastname: Labronici
authors.affiliation: Hip Group, Dr. Donato D'Angelo's Orthopedics and Traumatology Clinic, Hospital Santa Teresa, Petrópolis, RJ, Brazil.
authors.forename: Sergio Delmonte
authors.initials: SD
authors.lastname: Alves
authors.affiliation: Hip Group, Orthopedics and Traumatology, Dr. Donato D'Angelo's Orthopedics and Traumatology Clinic, Hospital Santa Teresa, Petrópolis, RJ, Brazil.
authors.forename: Anselmo Fernandes
authors.initials: AF
authors.lastname: da Silva
authors.affiliation: Hip Group, Dr. Donato D'Angelo's Orthopedics and Traumatology Clinic, Hospital Santa Teresa, Petrópolis, RJ, Brazil.
authors.forename: Gilberto Ribeiro
authors.initials: GR
authors.lastname: Giuberti
authors.affiliation: Hip Group, Dr. Donato D'Angelo's Orthopedics and Traumatology Clinic, Hospital Santa Teresa, Petrópolis, RJ, Brazil.
authors.forename: Justino Nóbrega
authors.initials: JN
authors.lastname: de Azevedo Neto
authors.affiliation: Hip Surgery Group, National Institute of Traumatology and Orthopedics (INTO, Instituto Nacional de Traumatologia e Ortopedia), Rio de Janeiro, RJ, Brazil.
authors.forename: Jorge Luiz
authors.initials: JL
authors.lastname: Mezzalira Penedo
keywords: Femur; Hip joint/pathology; Osteoarthritis, hip