title: Evaluation of the effect of custom burr holes on a surgeon's sense of screw fixation in revision porous metal cups.
abstract: OBJECTIVE
  It is common practice to burr custom holes in revision porous metal cups for screw insertion. The objective of this study was to determine how different hole types affect a surgeon's sense of screw fixation.
  
  
  METHODS
  Porous revision cups were prepared with pre-drilled and custom burred holes. Cups were held in place adjacent to synthetic bone material of varying density. Surgeons inserted screws through the different holes and materials. Surgeon subjective rating, compression, and torque was recorded.
  
  
  RESULTS
  The torque achieved was greater (p= 0.002) for screws through custom holes than pre-fabricated holes in low and medium density material, with no difference for high density. Peak compression was greater (p= 0.026) through the pre-fabricated holes only in high density material.
  
  
  CONCLUSIONS
  Use of burred holes affects the torque generated, and may decrease the amount of cup-acetabulum compression achieved.
authors.affiliation: Department of Surgery, Schulich School of Medicine & Dentistry, The University of Western Ontario, Ontario N6A 5B7, Canada.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Nyland
authors.affiliation: Department of Surgery, Schulich School of Medicine & Dentistry, The University of Western Ontario, Ontario N6A 5B7, Canada.
authors.forename: Brent A
authors.initials: BA
authors.lastname: Lanting
authors.affiliation: Imaging Research Laboratories, Robarts Research Institute, Ontario N6A 5B7, Canada.
authors.forename: Hristo N
authors.initials: HN
authors.lastname: Nikolov
authors.affiliation: Department of Surgery, Schulich School of Medicine & Dentistry, The University of Western Ontario, Ontario N6A 5B7, Canada.
authors.forename: Lyndsay E
authors.initials: LE
authors.lastname: Somerville
authors.affiliation: Department of Surgery, Schulich School of Medicine & Dentistry, The University of Western Ontario, Ontario N6A 5B7, Canada; Department of Medical Biophysics, Schulich School of Medicine & Dentistry, The University of Western Ontario, Ontario N6A 5B7, Canada; Surgical Innovation Program, Lawson Health Research Institute, Ontario N6A 5A5, Canada.
authors.forename: Matthew G
authors.initials: MG
authors.lastname: Teeter
authors.affiliation: Department of Surgery, Schulich School of Medicine & Dentistry, The University of Western Ontario, Ontario N6A 5B7, Canada.
authors.forename: James L
authors.initials: JL
authors.lastname: Howard
keywords: Biomechanics; Porous metal; Revision hip replacement; Screw fixation