title: 3D templating and patient-specific cutting guides (Knee-Plan) in total knee arthroplasty: postoperative CT-based assessment of implant positioning.
abstract: BACKGROUND
  The precision of bone cuts and the positioning of components influence the functionality and longevity of total knee arthroplasty (TKA). The objective of this study was to evaluate the results of TKA, performed after 3D preoperative templating, with the prosthesis implanted using custom cutting guides (Knee-Plan system, Symbios Orthopédie SA).
  
  
  METHODS
  This prospective study investigated 107 TKAs. Three-dimensional preoperative templating was carried out on the surface views and CT views to analyze the deformation of the lower limb and plan the implantation. The components were positioned in an individualized manner to realign the lower limb and provide ligament balance based on bone landmarks. Final component positioning was analyzed in the three planes with a postoperative CT scan. The preoperative and 1 year follow-up IKS and WOMAC scores were collected and compared.
  
  
  RESULTS
  All the cutting guides were stable and functional. Femoral component planning was reproduced with 0 ± 2 precision in the frontal plane (94%± 3), 2 ± 3 in the sagittal plane, and 0 ± 2 in the transverse plane. The precision of the tibial component was reproduced with 0 ± 2 precision in the frontal plane (93%± 3) and 0 ± 4 in the sagittal plane. The HKA angle increased from 177 ± 7 preoperatively to 180 ± 3 at 1 year of follow-up. The IKS and WOMAC scores were significantly improved at 1 year (P<0.0001).
  
  
  CONCLUSIONS
  The Knee-Plan system can be a realistic, simple, and reliable alternative to conventional cutting guides and to computer-assisted surgery for TKA implantation.
  
  
  METHODS
  IV; prospective cohort study.
authors.affiliation: Clinique Juge, 118, rue Jean-Mermoz, 13008 Marseille, France. Electronic address: jpfranceschi@gmail.com.
authors.forename: J-P
authors.initials: JP
authors.lastname: Franceschi
authors.affiliation: Clinique Juge, 118, rue Jean-Mermoz, 13008 Marseille, France.
authors.forename: A
authors.initials: A
authors.lastname: Sbihi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019643:Arthroplasty, Replacement / Q000295:instrumentation / Q000379:methods*; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation / Q000379:methods*; D015331:Cohort Studies; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000601:surgery; D005500:Follow-Up Studies; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000601:surgery*; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D011446:Prospective Studies; D025321:Surgery, Computer-Assisted / Q000379:methods*; D013977:Tibia / Q000000981:diagnostic imaging / Q000601:surgery; D014057:Tomography, X-Ray Computed
keywords: CTscan; Custom cutting guides; Patient-specific 3D preoperative templating; Total knee arthroplasty