title: In-vitro investigation of a noninvasive referencing technology for computer-assisted total hip arthroplasty.
abstract: The use of surgical navigation to aid in total joint replacement requires the bony fixation of reference marker arrays. In this context, a number of potential complications have been reported, including pin-site infection, soft tissue morbidity, and stress fracture. This study was performed to determine whether a femoral pinless, imageless navigation method for total hip arthroplasty (THA) is an accurate alternative method of measuring leg-length and offset change intraoperatively. Computer-assisted THA was simulated on a Sawbones bench test model including a femoral soft tissue model. Leg-length and offset changes were calculated by an imageless navigation system using the pinless measurement algorithm, in which the calculation of leg-length and offset changes is based on a specific realignment of the leg and then compared to corresponding measurements on a millimeter scale at the level of the femoral condyles. Mean difference in leg-length measurement (navigation versus millimeter paper) was 0.9 mm (95% confidence interval [CI]: 0.03-1.7 mm, P=.043), and the corresponding mean difference in offset was 1 mm (95% CI: 0.06-1.9 mm, P=.038). A noninvasive, pinless femoral system is a reliable tool for controlling leg length and offset during THA in an in-vitro setup. This system could lead to a reduction of potential risks associated with navigation techniques.
authors.affiliation: Department of Orthopedic Surgery, Regensburg University Medical Center, Asklepios Klinikum Bad Abbach, Kaiser-Karl V.-Allee 3, 93077 Bad Abbach, Germany. tobias.renkawitz@web.de
authors.forename: Tobias
authors.initials: T
authors.lastname: Renkawitz
authors.forename: Sabine
authors.initials: S
authors.lastname: Gneiting
authors.forename: Jens
authors.initials: J
authors.lastname: Schaumburger
authors.forename: Michael
authors.initials: M
authors.lastname: Woerner
authors.forename: Hans-Robert
authors.initials: HR
authors.lastname: Springorum
authors.forename: Joachim
authors.initials: J
authors.lastname: Grifka
authors.forename: Tibor
authors.initials: T
authors.lastname: Schuster
authors.forename: Ernst
authors.initials: E
authors.lastname: Sendtner
mesh_terms: D000465:Algorithms; D059925:Anatomic Landmarks / Q000473:pathology*; D053587:Arthrometry, Articular / Q000379:methods*; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D006621:Hip Joint / Q000473:pathology* / Q000601:surgery*; D006801:Humans; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D025321:Surgery, Computer-Assisted / Q000379:methods*