title: MRI abnormalities of the acetabular labrum and articular cartilage are common in healed Legg-Calvé-Perthes disease with residual deformities of the hip.
abstract: BACKGROUND
  Varying degrees of femoral deformity may result as Legg-Calvé-Perthes disease heals. Our aims were to investigate the prevalence of abnormalities of the acetabular labrum and cartilage, using noncontrast magnetic resonance imaging, and to correlate the findings with radiographic deformities that may exist after the healing of Legg-Calvé-Perthes disease.
  
  
  METHODS
  In a sample of ninety-nine patients with healed Legg-Calvé-Perthes disease, anteroposterior and lateral radiographs were used to assess the Stulberg classification, femoral head size and sphericity, femoral neck morphology, and acetabular version. A subgroup of fifty-four patients (fifty-nine hips) underwent noncontrast magnetic resonance imaging of the hip an average of eight years after disease onset. The acetabular labrum was evaluated according to a modified classification system, and the acetabular cartilage was evaluated for the presence of delamination and defects. The association among abnormalities of the acetabular labrum, articular cartilage, and radiographic deformities was assessed.
  
  
  RESULTS
  Abnormalities of the acetabular labrum and cartilage were found on magnetic resonance imaging scans in 75% and 47% of the hips, respectively. An alpha angle of ≥55° was the deformity most significantly associated with labral and cartilage abnormalities, followed by coxa brevis. Coxa magna and a higher greater trochanter showed a significant association with labral abnormalities only. Acetabular retroversion showed an increased risk for labral abnormalities when the alpha angle was normal. When deformities coexisted, the alpha angle showed the greatest relative risk for abnormality.
  
  
  CONCLUSIONS
  On the basis of magnetic resonance imaging evaluation of the hip, labral and cartilage abnormalities were a common finding in patients with healed Legg-Calvé-Perthes disease. Our results suggest that hip deformities are significantly associated with labral and cartilage abnormalities on magnetic resonance imaging, and the main predisposing factor was the asphericity of the femoral head with a reduced femoral head-neck offset.
authors: School of Medicine of Ribeirão Preto, University of São Paulo, Avenida Caramuru, N° 2100, apto 1424, República, Ribeirão Preto, São Paulo, 14030-000, Brazil. dacmaranho@gmail.com
authors: Daniel Augusto Carvalho
authors: DA
authors: Maranho
authors: Marcello Henrique
authors: MH
authors: Nogueira-Barbosa
authors: Ariane
authors: A
authors: Zamarioli
authors: José Batista
authors: JB
authors: Volpon
mesh_terms: D000077:Acetabulum / Q000473:pathology*; D000293:Adolescent; D002358:Cartilage, Articular / Q000473:pathology*; D002648:Child; D005270:Femur Head / Q000473:pathology; D005272:Femur Neck / Q000473:pathology; D006621:Hip Joint / Q000473:pathology*; D006801:Humans; D016916:Joint Deformities, Acquired / Q000473:pathology*; D007873:Legg-Calve-Perthes Disease / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D011446:Prospective Studies; D012307:Risk Factors; D055815:Young Adult