title: Prognostic factors associated with a subchondral insufficiency fracture of the femoral head.
abstract: OBJECTIVE
  The aim of this study was to identify the risk factors associated with the prognosis of a subchondral insufficiency fracture of the femoral head (SIF).
  
  
  METHODS
  Between June 2002 and July 2009, 25 patients diagnosed with SIF were included in this study. Sequential radiographs were evaluated for the progression of collapse. Clinical profiles, including age, body mass index, follow-up period and Singh's index, were documented. The morphological characteristics of the low-intensity band on T(1) weighted MRI were also examined with regards to four factors: band length, band thickness, the length of the weight-bearing portion and the band length ratio (defined as the proportion of the band length to the weight-bearing portion of the femoral head in the slice through the femoral head centre).
  
  
  RESULTS
  Radiographically, a progression of collapse was observed in 15 of 25 (60.0%) patients. The band length in patients with progression of collapse [22.5 mm; 95% confidence interval (CI) 17.7, 27.3] was significantly larger than in patients without a progression of collapse (13.4 mm; 95% CI 7.6, 19.3; p<0.05). The band length ratio in patients with progression of collapse (59.8%; 95% CI 50.8, 68.9) was also significantly higher than in patients without a progression of collapse (40.9%; 95% CI 29.8, 52.0; p<0.05). No significant differences were present in the other values.
  
  
  CONCLUSIONS
  These results indicate that the band length and the band length ratio might be predictive for the progression of collapse in SIF.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Iwasaki
authors.forename: T
authors.initials: T
authors.lastname: Yamamoto
authors.forename: G
authors.initials: G
authors.lastname: Motomura
authors.forename: S
authors.initials: S
authors.lastname: Ikemura
authors.forename: T
authors.initials: T
authors.lastname: Mawatari
authors.forename: Y
authors.initials: Y
authors.lastname: Nakashima
authors.forename: Y
authors.initials: Y
authors.lastname: Iwamoto
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D018450:Disease Progression; D005260:Female; D005265:Femoral Neck Fractures / Q000473:pathology*; D015775:Fractures, Stress / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011379:Prognosis; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D055815:Young Adult