title: Common site of subchondral insufficiency fractures of the femoral head based on three-dimensional magnetic resonance imaging.
abstract: OBJECTIVE
  The objective of this study was to investigate the common sites of subchondral insufficiency fractures of the femoral head (SIF) based on three-dimensional (3-D) reconstruction of MR images.
  
  
  METHODS
  In 33 hips of 31 consecutive patients diagnosed with SIF, 3-D reconstruction of the bone, fracture, and acetabular edge was performed using MR images. These 3-D images were used to measure the fractured areas and clarify the positional relationship between the fracture and degree of acetabular coverage.
  
  
  RESULTS
  The fractured area in the anterior portion was significantly larger than in the posterior area. In 11 cases, the fractures contacted the acetabular edge and were distributed on the lateral portion. The indices of acetabular coverage (center-edge angle and acetabular head index) in these cases were less than the normal range. In the remaining 22 cases, the fractures were apart from the acetabular edge and distributed on the mediolateral centerline of the femoral head. The majority of these cases had normal acetabular coverage.
  
  
  CONCLUSIONS
  The common site of SIF is the anterior portion. In addition, two types of SIF are proposed: (1) Lateral type: the contact stress between the acetabular edge and lateral portion of the femoral head causes SIF based on the insufficient acetabular coverage, and (2) Central type: the contact stress between the acetabular surface and the mediolateral center of the femoral head causes SIF independent from the insufficiency of acetabular coverage. These findings may be useful for considering the treatment and prevention of SIF.
authors.affiliation: Department of Orthopaedic Surgery Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Kenyu
authors.initials: K
authors.lastname: Iwasaki
authors.affiliation: Department of Orthopaedic Surgery Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan. yamataku@ortho.med.kyushu-u.ac.jp.
authors.forename: Takuaki
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: Department of Orthopaedic Surgery Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Goro
authors.initials: G
authors.lastname: Motomura
authors.affiliation: Department of Orthopaedic Surgery Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Karasuyama
authors.affiliation: Department of Orthopaedic Surgery Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Sonoda
authors.affiliation: Department of Orthopaedic Surgery Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kubo
authors.affiliation: Department of Orthopaedic Surgery Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Iwamoto
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005270:Femur Head / Q000293:injuries* / Q000473:pathology*; D015775:Fractures, Stress / Q000473:pathology*; D006620:Hip Fractures / Q000473:pathology*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
keywords: Common site; Magnetic resonance imaging; Subchondral insufficiency fracture of the femoral head; Type