title: Femoral cement extraction in revision total hip arthroplasty--an in vitro study comparing computer-assisted freehand-navigated cement removal to conventional cement extraction.
abstract: BACKGROUND
  Revision surgery of cemented femoral stems in total hip arthroplasty is gaining more and more importance, but cement removal in revision hip arthroplasty may be technically challenging. Conventional manual cement removal can be time consuming and be associated with complications such as cortical perforation, fracture, or bone loss. The aim of this study was to investigate the practicability of computer-navigated cement removal.
  
  
  METHODS
  In an in vitro study, we examined the removal of the bone cement out of composite bones. To evaluate accuracy, the bones were scanned before and after cement removal with the ISO-C three-dimensional C-arm computed tomography system to determine the amount of unremoved cement and the loss of bone stock. The data of freehand-navigated cement removal is compared to conventionally extracted cement using levers and drills under X-ray control.
  
  
  RESULTS
  The mean time for cement removal was 29 ± 5 min for the conventional method and 32 ± 8 min for the freehand-navigated cement removal. Here, excepting the preparatory examinations, the navigated cement removal only took 13 ± 5 min. The measured temperature during polymerization was 36 ± 5 °C and during navigated cement removal was 37 ± 8 °C. In the distal part of the femur, cement removal was more accurate with the conventional method compared to the navigated one.
  
  
  CONCLUSIONS
  The freehand-navigated cement removal, with the exception of the preparatory examinations, is time saving compared to the conventional method. However, a potential for technical development especially for the milling device and accuracy exist.
authors.forename: Torsten
authors.initials: T
authors.lastname: Mumme
authors.forename: Max Julian
authors.initials: MJ
authors.lastname: Friedrich
authors.forename: Henrik
authors.initials: H
authors.lastname: Rode
authors.forename: Sascha
authors.initials: S
authors.lastname: Gravius
authors.forename: Stefan
authors.initials: S
authors.lastname: Andereya
authors.forename: Ralf
authors.initials: R
authors.lastname: Müller-Rath
authors.forename: Matias
authors.initials: M
authors.lastname: de la Fuente
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D001843:Bone Cements; D020878:Device Removal / Q000379:methods*; D005269:Femur / Q000000981:diagnostic imaging / Q000601:surgery; D006622:Hip Prosthesis; D006801:Humans; D012086:Reoperation / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D025321:Surgery, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D001843:Bone Cements