title: Evaluation of the accuracy of patient-specific cutting blocks for total knee arthroplasty: a meta-analysis.
abstract: OBJECTIVE
  Because published studies on the accuracy achieved with patient-specific guides during total knee arthroplasty (TKA) contradict each other, this systematic review and meta-analysis sought to compare radiological TKA outcomes when patient-specific cutting blocks (PSCB) were used to the outcomes when standard manual instrumentation was used.
  
  
  METHODS
  The meta-analysis was implemented according to PRISMA Statement Criteria. The primary endpoint was the hip-knee-ankle (HKA) angle, which represents the leg's mechanical axis. The accuracy of component placement in the coronal and sagittal planes, and the accuracy of femoral component rotation were also compiled. After testing for publication bias and heterogeneity across studies, data were aggregated random-effects modeling when necessary.
  
  
  RESULTS
  Fifteen articles were included: 916 total knee arthroplasty cases in the PSCB group and 998 in the MI group. The mechanical axis did not differ between the two groups (weighted mean difference 0.07°; 95 % CI, -0.5° to 0.65°; p = 0.8). Risk ratio analysis revealed no protective effect of using PSCB relative to the appearance of HKA angle outliers (RR = 0.88; 95 % CI, 0.68-1.13; p = 0.3). There was a trend towards a protective effect with PSCB for the risk of femoral component outliers, but the opposite was observed for the tibial component. The implantation procedure was stopped in 30 cases because the surgeon-authors found excessive discrepancies between the intra-operative observations and the pre-operative plan.
  
  
  CONCLUSIONS
  This meta-analysis found no evidence that using patient-specific cutting blocks provides superior accuracy to using manual instrumentation during TKA.
authors.affiliation: Pôle Institut Locomoteur, Hôpital Pierre-Paul Riquet, Place du Docteur Baylac, TSA 40031, 31059, Toulouse, France, cavaignac.etienne@gmail.com.
authors.forename: Etienne
authors.initials: E
authors.lastname: Cavaignac
authors.forename: Regis
authors.initials: R
authors.lastname: Pailhé
authors.forename: Gregoire
authors.initials: G
authors.lastname: Laumond
authors.forename: Jérôme
authors.initials: J
authors.lastname: Murgier
authors.forename: Nicolas
authors.initials: N
authors.lastname: Reina
authors.forename: Jean Michel
authors.initials: JM
authors.lastname: Laffosse
authors.forename: Emilie
authors.initials: E
authors.lastname: Bérard
authors.forename: Philippe
authors.initials: P
authors.lastname: Chiron
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000601:surgery; D020370:Osteoarthritis, Knee / Q000601:surgery*; D011859:Radiography; D018570:Risk Assessment; D012399:Rotation; D025321:Surgery, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D013977:Tibia / Q000601:surgery; D016896:Treatment Outcome