title: Greater accuracy in positioning of the acetabular cup by using an image-free navigation system.
abstract: In a prospective and randomised clinical study, acetabular cups were implanted free-hand (control group n=22) or with computer assistance using an image-free navigation system (study group n=23). The cup position was determined postoperatively on pelvic CT. An average inclination of 42.3 degrees (range: 30 degrees -53 degrees ; SD+/-7.0 degrees ) and an average anteversion of 24.0 degrees (range: -3 degrees to 51 degrees ; SD+/-15.0 degrees ) were found in the control group, and an average inclination of 45.0 degrees (range: 40 degrees -50 degrees ; SD+/-2.8 degrees ) and an average anteversion of 14.4 degrees (range: 5 degrees -25 degrees ; SS+/-5.0 degrees ) in the computer-assisted study group. The deviations from the desired cup position (45 degrees inclination, 15 degrees anteversion) were significantly lower in the computer-assisted study group (p<0.001 each). While only 11/22 of the cups in the control group were within the Lewinnek safe zone, 21/23 of the cups in the study group were placed in this target region (p=0.003).
authors.affiliation: Department of Orthopaedic Surgery, University of Regensburg, Bad Abbach, Germany. thomas.kalteis@klinik.uni-regensburg.de
authors.forename: T
authors.initials: T
authors.lastname: Kalteis
authors.forename: M
authors.initials: M
authors.lastname: Handel
authors.forename: T
authors.initials: T
authors.lastname: Herold
authors.forename: L
authors.initials: L
authors.lastname: Perlick
authors.forename: H
authors.initials: H
authors.lastname: Baethis
authors.forename: J
authors.initials: J
authors.lastname: Grifka
mesh_terms: D000077:Acetabulum; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery*; D011446:Prospective Studies; D018709:Statistics, Nonparametric; D025321:Surgery, Computer-Assisted; D016896:Treatment Outcome