title: Leg length and offset measures with a pinless femoral reference array during THA.
abstract: The bony fixation of reference marker arrays used for computer-assisted navigation during total hip arthroplasty (THA) theoretically involves the risk of fracture, infection, and/or pin loosening. We asked whether intraoperative assessment of leg length (LL) and offset (OS) changes would be accurate using a novel pinless femoral reference system in conjunction with an imageless measurement algorithm based on specific realignment of the relationship between a dynamic femoral and pelvis reference array. LL/OS measurements were recorded during THA in 17 cadaver specimen hips. Preoperatively and postoperatively, specimens were scanned using CT. Linear radiographic LL/OS changes were determined by two investigators using visible fiducial landmarks and image processing software. We found a high correlation of repeated measurements within and between (both 0.95 or greater) the two examiners who did the CT assessments. Pinless LL/OS values showed mean differences less than 1 mm and correlations when compared with CT measurements.
authors.affiliation: Department of Orthopaedic Surgery, Regensburg University Medical Center, Regensburg, Germany. tobias.renkawitz@web.de
authors.forename: Tobias
authors.initials: T
authors.lastname: Renkawitz
authors.forename: Tibor
authors.initials: T
authors.lastname: Schuster
authors.forename: Joachim
authors.initials: J
authors.lastname: Grifka
authors.forename: Thomas
authors.initials: T
authors.lastname: Kalteis
authors.forename: Ernst
authors.initials: E
authors.lastname: Sendtner
mesh_terms: D000465:Algorithms; D019644:Arthroplasty, Replacement, Hip / Q000379:methods* / Q000592:standards; D002102:Cadaver; D005260:Female; D005269:Femur / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D006801:Humans; D007866:Leg / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D008297:Male; D015588:Observer Variation; D012015:Reference Standards; D015203:Reproducibility of Results; D025321:Surgery, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed