title: Accuracy of manual instrumentation of tibial cutting guide in total knee arthroplasty.
abstract: OBJECTIVE
  The aim of this study was to evaluate the accuracy of conventional instrumentation for tibial resection in total knee arthroplasty (TKA) as assessed by a computer-based navigation system during each phase of the surgical procedure. The hypothesis is that conventional instrumentation fails to achieve optimal accuracy in final implant positioning, thus leading to surgical errors.
  
  
  METHODS
  Forty primary TKAs were performed. The resection guide was placed using an extramedullary guide. Accurate guide positioning was assessed by the navigation system prior to the osteotomy. The alignment measurement was repeated after resection and after component implantation in order to quantify the deviation caused by the manual positioning of the prosthetic components. A deviation ≥2° was considered unsatisfactory.
  
  
  RESULTS
  In the frontal plane, unsatisfactory results observed were as follows: 15 % with reference to manual positioning of the resection guide and 10 % with reference to definition of the resection plane with a tendency towards varus malalignment. In the sagittal plane, unsatisfactory results were as follows: 45 % with reference to manual positioning of the resection guide and 40 % with reference to definition of the resection plane with a trend of decreased tibial slope angle. The deviation between bone resection and subsequent implant placement was ≥2° in none of the cases.
  
  
  CONCLUSIONS
  The study confirms the hypothesis that conventional instrumentation fails to achieve optimal accuracy in the positioning of the tibial component. During each phase of the surgical procedure, a tendency towards varus malalignment and a decreased tibial slope angle were observed.
  
  
  METHODS
  II.
authors.affiliation: Orthopaedic Unit and "Kirk Kilgour" Sports Injury Centre, S. Andrea Hospital, University of Rome "Sapienza", Via Grottarossa, 1035, Rome (RM), Italy.
authors.forename: R
authors.initials: R
authors.lastname: Iorio
authors.forename: G
authors.initials: G
authors.lastname: Bolle
authors.forename: F
authors.initials: F
authors.lastname: Conteduca
authors.forename: L
authors.initials: L
authors.lastname: Valeo
authors.forename: J
authors.initials: J
authors.lastname: Conteduca
authors.forename: D
authors.initials: D
authors.lastname: Mazza
authors.forename: A
authors.initials: A
authors.lastname: Ferretti
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D059925:Anatomic Landmarks; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation* / Q000379:methods; D017760:Bone Malalignment / Q000209:etiology / Q000517:prevention & control*; D006801:Humans; D007720:Knee Prosthesis; D019300:Medical Errors / Q000517:prevention & control*; D020370:Osteoarthritis, Knee / Q000601:surgery*; D011183:Postoperative Complications / Q000517:prevention & control*; D025321:Surgery, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D013977:Tibia / Q000033:anatomy & histology / Q000601:surgery*; D016896:Treatment Outcome