title: Inter-observer and intra-observer reliability in the radiographic diagnosis of avascular necrosis of the femoral head following reconstructive hip surgery in children with cerebral palsy.
abstract: OBJECTIVE
  The incidence of avascular necrosis (AVN) following reconstructive hip surgery in cerebral palsy (CP) ranges from 0 to 69 % in the current literature. The purpose of this study was to determine the inter- and intra-observer reliability of radiographically diagnosing AVN in children with CP after hip surgery.
  
  
  METHODS
  A retrospective review of 65 children with CP who had reconstructive hip surgery between 2009 and 2012 at BC Children's Hospital was completed. Anterior-posterior and lateral radiographs were presented to four pediatric orthopaedic surgeons over two rounds. Surgeons were asked to review the set of unidentified radiographs and comment 'yes' or 'no' for the presence of AVN. Two weeks later the same set of radiographs was sent in a different order and the surgeons were again asked to comment on AVN. Inter- and intra-observer reliability was determined using kappa statistics.
  
  
  RESULTS
  The intra-observer reliability ranged from 0.65 to 0.88 with an average score of 0.76. Inter-observer reliability showed greater variability, ranging from 0.41 to 0.77 with an average score of 0.56 across all surgeons.
  
  
  CONCLUSIONS
  Although the intra-rater reliability produced a strength of "good" and the inter-rater reliability a strength of "moderate" agreement, the variability within these scores is clinically important as it demonstrates the difficulty in identifying AVN. This may explain the variability in AVN that is reported in the literature. The need for further education and research in the diagnosis of AVN in children with CP who have undergone reconstructive hip surgery is clinically necessary.
authors.affiliation: Department of Orthopaedic Surgery, BC Children's Hospital, 1D.66, 4480 Oak St, Vancouver, BC, V6H 3V4, Canada.
authors.forename: Kim
authors.initials: K
authors.lastname: Hesketh
authors.affiliation: The Children's Hospital of Philadelphia, Philadelphia, PA, USA.
authors.forename: Wudbhav
authors.initials: W
authors.lastname: Sankar
authors.affiliation: Paediatric Orthopaedic Service, Manipal, Karnataka, India.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Joseph
authors.affiliation: Hospital for Sick Children, Toronto, ON, Canada.
authors.forename: Unni
authors.initials: U
authors.lastname: Narayanan
authors.affiliation: Department of Orthopaedic Surgery, BC Children's Hospital, 1D.66, 4480 Oak St, Vancouver, BC, V6H 3V4, Canada. kmulpuri@cw.bc.ca.|Department of Orthopedics, University of British Columbia, Vancouver, BC, Canada. kmulpuri@cw.bc.ca.
authors.forename: Kishore
authors.initials: K
authors.lastname: Mulpuri
keywords: AVN; Avascular necrosis; Cerebral palsy; Inter-observer and intra-observer reliability; Reconstructive hip surgery for children with CP