title: Computer assisted surgery. Its usefulness in different levels of pre-operative deformities.
abstract: OBJECTIVE
  To compare the results obtained with computer assisted surgery with conventional techniques and evaluate the influence of navigation at different levels of preoperative deformity.
  A retrospective study was conducted on 100 cases with primary total knee arthroplasty performed with conventional or computer assisted surgery. A comparison was made of the post-operative mechanical axis of the lower limb between both groups and in terms of pre-operative deformity.
  
  
  RESULTS
  Optimal alignment is most often obtained by using the navigation system (62%) than by a conventional technique (36%). Patients with deformities under 10° varus showed a mean post-operative alignment within the optimal range (0±3° deviation from the neutral mechanical axis), while those with more than 15° of varus show an alignment out of range, regardless of the technique used (p=.002). In those with a deformity of between 10 and 15° of pre-operative varus alignment, values were found closer to the neutral axis in the navigation group (178.7°) than in the conventional technique (175.5°), although these differences are not statistically significant (p=.127).
  
  
  CONCLUSIONS
  Post-operative alignment obtained with navigation is better than with the conventional technique, with a smaller percentage of cases out of range, and greater accuracy in placing implants. A potential benefit was observed in navigation for cases with deformities of between 10 and 15° of varus.
authors.affiliation: Servicio de Cirugía Ortopédica y Traumatología, Hospital Universitario de Fuenlabrada, Fuenlabrada, Madrid, España. Electronic address: pablo.benavente.rodriguez@gmail.com.
authors.forename: P
authors.initials: P
authors.lastname: Benavente
authors.affiliation: Servicio de Cirugía Ortopédica y Traumatología, Hospital Universitario de Fuenlabrada, Fuenlabrada, Madrid, España.
authors.forename: C
authors.initials: C
authors.lastname: López Orosa
authors.affiliation: Servicio de Cirugía Ortopédica y Traumatología, Hospital Universitario de Fuenlabrada, Fuenlabrada, Madrid, España.
authors.forename: J A
authors.initials: JA
authors.lastname: Oteo Maldonado
authors.affiliation: Servicio de Cirugía Ortopédica y Traumatología, Hospital Universitario de Fuenlabrada, Fuenlabrada, Madrid, España.
authors.forename: A
authors.initials: A
authors.lastname: Orois Codesal
authors.affiliation: Servicio de Cirugía Ortopédica y Traumatología, Hospital Universitario de Fuenlabrada, Fuenlabrada, Madrid, España.
authors.forename: F J
authors.initials: FJ
authors.lastname: García Lázaro
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D017760:Bone Malalignment / Q000175:diagnosis / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000150:complications / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D057234:Preoperative Period; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D025321:Surgery, Computer-Assisted / Q000379:methods*
keywords: Alineación postoperatoria; Artroplastia total de rodilla; Cirugía asistida por ordenador; Computer assisted surgery; Navegación; Navigation; Post-operative alignment; Total knee replacement