title: Femoropatellar radiographic alterations in cases of anterior cruciate ligament failure.
abstract: OBJECTIVE
  To make a comparative analysis on three femoropatellar radiographic parameters, between knees with chronic failure of the anterior cruciate ligament (ACL) and normal knees.
  
  
  METHODS
  Thirty volunteer patients with a diagnosis of unilateral isolated chronic ACL injury for more than one year and a normal contralateral knee were selected. Digital radiographs were produced for all the patients, on both knees in absolute lateral view at 30° of flexion, with and without load-bearing on one leg, and in axial view of the patella at 30°. The Caton-Deschamps patellar height index, Merchant patellar congruence angle and Laurin lateral patellar tilt angle were measured on the radiographs obtained from the normal knees and knees with ACL injuries, and comparative analysis was performed between these two groups.
  
  
  RESULTS
  The patellar height was statistically significantly lower (p < 0.001) in the knees with ACL failure than in the normal knees, both on radiographs without loading and on those with single-foot loading. The Merchant patellar congruence angle was significantly smaller (p < 0.001) in the normal knees and the lateral patellar tilt angle was smaller (p < 0.001) in the knees with ACL failure.
  
  
  CONCLUSIONS
  Chronic ACL failure gave rise to a statistically significant change in the femoropatellar radiographic values studied (p < 0.001). Knees with injuries to this ligament presented lower patellar height values, greater tilt and lateral displacement of the patella, in relation to the femoral trochlea, in comparison with the normal contralateral knees.
authors.affiliation: Orthopedics and Traumatology Service, University Hospital, Federal University of Sergipe, Aracaju, SE, Brazil.
authors.forename: Diego Protásio
authors.initials: DP
authors.lastname: de Vasconcelos
authors.affiliation: Knee Surgery Center, National Institute of Traumatology and Orthopedics (INTO), Rio de Janeiro, RJ, Brazil.
authors.forename: Alan
authors.initials: A
authors.lastname: de Paula Mozella
authors.affiliation: Knee Surgery Center, National Institute of Traumatology and Orthopedics (INTO), Rio de Janeiro, RJ, Brazil.
authors.forename: Pedro Guilme Teixeira
authors.initials: PG
authors.lastname: de Sousa Filho
authors.affiliation: Knee Surgery Center, National Institute of Traumatology and Orthopedics (INTO), Rio de Janeiro, RJ, Brazil.
authors.forename: Gustavo Cardilo
authors.initials: GC
authors.lastname: Oliveira
authors.affiliation: Knee Surgery Center, National Institute of Traumatology and Orthopedics (INTO), Rio de Janeiro, RJ, Brazil.
authors.forename: Hugo Alexandre
authors.initials: HA
authors.lastname: de Araújo Barros Cobra
keywords: Anterior cruciate ligament; Joint instability; Patellofemoral joint