title: Patient-specific positioning guides versus manual instrumentation for total knee arthroplasty: an intraoperative comparison.
abstract: Traditional manual instruments for total knee arthroplasty are associated with a malalignment rate of nearly 30%. Patient-specific positioning guides, developed to help address alignment, may also influence other intraoperative factors. This study compared a consecutive series of 270 Vanguard total knee replacements performed with Signature patient-specific positioning guides (study group) to a consecutive series of 595 similar knee replacements performed with manual instrumentation (control group). The study group averaged 16.7 fewer minutes in the operating room (p < .001), utilized tibial inserts that averaged 0.4 mm thinner with a smaller proportion of "thick" tibial inserts (14-18 mm) (p < .001), and required fewer transfusions (p = .022). The Signature-derived surgical plan accurately predicted correct femoral and tibial component sizes in 86.3% and 70.3% of the cases, respectively. These rates increased to 99.3% and 99.2%, respectively, for accuracy to within one size of the surgical plan, similar to published values for manual instrumentation.
authors.forename: Safa
authors.initials: S
authors.lastname: Kassab
authors.forename: William S
authors.initials: WS
authors.lastname: Pietrzak
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee; D001803:Blood Transfusion / Q000706:statistics & numerical data; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D007430:Intraoperative Care; D007719:Knee Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D007720:Knee Prosthesis; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D061646:Operative Time; D056888:Patient Positioning / Q000379:methods*; D017755:Prosthesis Fitting / Q000379:methods*; D025321:Surgery, Computer-Assisted / Q000379:methods*; D013525:Surgical Instruments / Q000706:statistics & numerical data; D014057:Tomography, X-Ray Computed