title: Drill wobble - effect on femoral tunnel aperture during anterior cruciate ligament reconstruction.
abstract: BACKGROUND
  In anterior cruciate ligament reconstruction performed using cortical button fixation on the femur, we have observed a "wobble" effect that can occur when a cannulated femoral drill is used over a guide pin that is not securely fixed in bone. Our study assessed the effect of drill "wobble" on femoral tunnel aperture in sawbones.
  
  
  METHODS
  Femoral tunnels were drilled in sawbones, which had been divided in two groups of 10 each, per drilling technique. The "wobble" technique group had the smaller cortical button drill passed before drilling the graft socket with the bigger diameter femoral drill. In contrast, in the "non-wobble" technique group, the smaller cortical button drill was passed after drilling the graft socket. The aperture dimensions: antero-posterior, proximo-distal and oblique, as well as the length of each tunnel, were measured.
  
  
  RESULTS
  While the average dimensions of the tunnels were similar between the two techniques, there was significantly more variation in the antero-posterior measurements for the wobble technique as compared to the non-wobble technique (mean 7.3 mm, SD 0.28 mm, and mean 7.3 mm, SD 0.11 mm, respectively; Brown-Forsythe test, p 0.02).
  
  
  CONCLUSIONS
  We conclude that using the "socket first" "non-wobble" technique is a single surgical technical step surgeons can employ to decrease variability in tunnel aperture and size.
authors.affiliation: Division of Orthopaedic Surgery, McGill University Health Centre, 1650 Cedar Avenue, A5-175.1, Montreal, QC, H3G 1A4, Canada. naser.alnusif@mail.mcgill.ca.
authors.forename: Naser
authors.identifier: http://orcid.org/0000-0002-6801-9205
authors.initials: N
authors.lastname: Alnusif
authors.affiliation: Division of Orthopaedic Surgery, McGill University Health Centre, 1650 Cedar Avenue, A5-175.1, Montreal, QC, H3G 1A4, Canada.
authors.forename: Adam
authors.initials: A
authors.lastname: Hart
authors.affiliation: Division of Orthopaedic Surgery, McGill University Health Centre, 1650 Cedar Avenue, A5-175.1, Montreal, QC, H3G 1A4, Canada.
authors.forename: Maher
authors.initials: M
authors.lastname: Baroudi
authors.affiliation: Division of Orthopaedic Surgery, McGill University Health Centre, 1650 Cedar Avenue, A5-175.1, Montreal, QC, H3G 1A4, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: Marien
authors.affiliation: Division of Orthopaedic Surgery, McGill University Health Centre, 1650 Cedar Avenue, A5-175.1, Montreal, QC, H3G 1A4, Canada.
authors.forename: Mark
authors.initials: M
authors.lastname: Burman
authors.affiliation: Division of Orthopaedic Surgery, McGill University Health Centre, 1650 Cedar Avenue, A5-175.1, Montreal, QC, H3G 1A4, Canada.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Martineau
keywords: Anterior cruciate ligament; Anterior cruciate ligament reconstruction failure; Femoral tunnel placement; Wobble effect