title: Osteopenic features of the hip joint in patients with cerebral palsy: a hospital-based study.
abstract: OBJECTIVE
  We aimed to evaluate the bone mineral density of the hip joint in patients with cerebral palsy (CP).
  
  
  METHODS
  Patients with CP younger than 18 years who underwent three-dimensional hip examination by computed tomography were analysed. Bone attenuation of the acetabulum and femur was measured as Hounsfield units (HU), and was adjusted for affecting factors such as hip instability and Gross Motor Function Classification System (GMFCS).
  
  
  RESULTS
  One hundred and twenty-six patients with CP and 86 typically developing participants were included. The average bone attenuation was significantly lower in those with CP than in the comparison group (acetabulum: 70.8HU, 95% confidence interval [95% CI] 59.9-81.8; femur: 82.2HU, 95% CI 70.4-95.8). Compared with GMFCS levels I to III, bone attenuation was significantly lower for GMFCS levels IV (acetabulum: 30.9HU, 95% CI 15.7-46.2; femur: 39.7HU, 95% CI 19.9-59.5) and V (acetabulum: 51.7HU, 95% CI 35.9-67.5; femur: 72.5HU, 95% CI 51.9-93.0). The average bone attenuation decreased when the migration percentage was over 37% (acetabulum: 11.6HU, 95% CI 1.4-24.6; femur: 26.8HU, 95% CI 9.9-43.6).
  
  
  CONCLUSIONS
  Bone attenuation of the acetabulum and femur was significantly affected both by GMFCS level and by severity of hip instability.
authors.affiliation: Department of Orthopaedic Surgery, Yeol Lin Hospital, Kyungki, South Korea.
authors.forename: Sang Young
authors.initials: SY
authors.lastname: Moon
authors.affiliation: Department of Mathematics, Ajou University, Kyungki, South Korea.
authors.forename: Soon-Sun
authors.initials: SS
authors.lastname: Kwon
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, Kyungki, South Korea.
authors.forename: Byung Chae
authors.initials: BC
authors.lastname: Cho
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, Kyungki, South Korea.
authors.forename: Chin Youb
authors.initials: CY
authors.lastname: Chung
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, Kyungki, South Korea.
authors.forename: Kyoung Min
authors.initials: KM
authors.lastname: Lee
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, Kyungki, South Korea.
authors.forename: Ki Hyuk
authors.initials: KH
authors.lastname: Sung
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, Kyungki, South Korea.
authors.forename: Myoung Ki
authors.initials: MK
authors.lastname: Chung
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, Kyungki, South Korea.
authors.forename: Arif
authors.initials: A
authors.lastname: Zulkarnain
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, Kyungki, South Korea.
authors.forename: Yong Sung
authors.initials: YS
authors.lastname: Kim
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, Kyungki, South Korea. pmsmed@gmail.com.
authors.forename: Moon Seok
authors.initials: MS
authors.lastname: Park
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging*; D000293:Adolescent; D015519:Bone Density; D001851:Bone Diseases, Metabolic / Q000000981:diagnostic imaging* / Q000209:etiology; D002547:Cerebral Palsy / Q000150:complications / Q000000981:diagnostic imaging*; D002648:Child; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging*; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging* / Q000209:etiology; D008297:Male; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed