title: Reliable angle assessment during periacetabular osteotomy with a novel device.
abstract: We developed and assessed a measuring device for intraoperative assessment of the acetabular index and center edge angle during acetabular reorientation in periacetabular osteotomy. We asked whether reliable assessment of angles could be made using the device; to be reliable we presumed the variability of angle measurements should not exceed that of inherent variability when assessing angles on radiographs (+/- 5 degrees ). The device was mounted bilaterally on the pelvis, and using fluoroscopy, angle measurements were obtained with adjustable measuring discs. We conducted a cadaver study to assess intraobserver and interobserver variability of the device and to assess if pelvic positioning influenced variation of measurements. Intraoperative measurements of 35 consecutive patients were compared with measurements on postoperative radiographs. Intraoperatively obtained angle measurements differed less than +/- 5 degrees from measurements on postoperative radiographs and the intraobserver and interobserver variability of the device were confined within +/- 5 degrees . Positioning did not influence the variation of angle measurements beyond intraobserver variability of the device when applying arcs of tilt and rotation of +/- 12.5 degrees . We believe the device is a potentially helpful tool in the periacetabular osteotomy. It is simple to use and facilitates repeated reliable angle measurements during acetabular reorientation, making intraoperative radiographs unnecessary.
authors.affiliation: Orthopaedic Research Unit, University Hospital of Aarhus, Tage-Hansens Gade 2, Building 7B, DK-8000, Aarhus C, Denmark. a_troelsen@hotmail.com
authors.forename: Anders
authors.initials: A
authors.lastname: Troelsen
authors.forename: Brian
authors.initials: B
authors.lastname: Elmengaard
authors.forename: Lone
authors.initials: L
authors.lastname: Rømer
authors.forename: Kjeld
authors.initials: K
authors.lastname: Søballe
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D000293:Adolescent; D000328:Adult; D002102:Cadaver; D004867:Equipment Design; D005260:Female; D005471:Fluoroscopy / Q000295:instrumentation; D006618:Hip Dislocation, Congenital / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D007430:Intraoperative Care; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010027:Osteotomy / Q000295:instrumentation*; D010384:Pelvic Bones / Q000000981:diagnostic imaging; D011446:Prospective Studies; D011857:Radiographic Image Interpretation, Computer-Assisted; D016059:Range of Motion, Articular; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D016896:Treatment Outcome