title: Accuracy of patient specific cutting blocks in total knee arthroplasty.
abstract: BACKGROUND
  Long-term survival of total knee arthroplasty (TKA) is mainly determined by optimal positioning of the components and prosthesis alignment. Implant positioning can be optimized by computer assisted surgery (CAS). Patient specific cutting blocks (PSCB) seem to have the potential to improve component alignment compared to the conventional technique and to be comparable to CAS.
  
  
  METHODS
  113 knees were selected for PSI and included in this study. Pre- and postoperative mechanical axis, represented by the hip-knee-angle (HKA), the proximal tibial angle (PTA), the distal femoral angle (DFA), and the tibial slope (TS) were measured and the deviation from expected ideal values was calculated.
  
  
  RESULTS
  With a margin of error of ±3°, success rates were 81.4% for HKA, 92.0% for TPA, and 94.7% for DFA. With the margin of error for alignments extended to ±4°, we obtained a success rate of 92.9% for the HKA, 98.2% for the PTA, and 99.1% for the DFA. The TS showed postoperative results of 2.86±2.02° (mean change 1.76±2.85°).
  
  
  CONCLUSIONS
  PSCBs for TKA seem to restore the overall leg alignment. Our data suggest that each individual component can be implanted accurately and the results are comparable to the ones in CAS.
authors.affiliation: Abteilung für Orthopädie und Traumatologie des Bewegungsapparates, Bürgerspital Solothurn, Schöngrünstrasse 42, 4500 Solothurn, Switzerland.
authors.forename: Naeder
authors.initials: N
authors.lastname: Helmy
authors.affiliation: Abteilung für Orthopädie und Traumatologie des Bewegungsapparates, Bürgerspital Solothurn, Schöngrünstrasse 42, 4500 Solothurn, Switzerland.
authors.forename: Mai Lan
authors.identifier: 0000-0002-1150-8059
authors.initials: ML
authors.lastname: Dao Trong
authors.affiliation: Abteilung für Orthopädie und Traumatologie des Bewegungsapparates, Bürgerspital Solothurn, Schöngrünstrasse 42, 4500 Solothurn, Switzerland.
authors.forename: Stefanie P
authors.initials: SP
authors.lastname: Kühnel
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001696:Biomechanical Phenomena; D005269:Femur / Q000000981:diagnostic imaging; D006801:Humans; D007719:Knee Joint / Q000473:pathology / Q000601:surgery*; D019736:Prostheses and Implants; D016032:Randomized Controlled Trials as Topic; D025321:Surgery, Computer-Assisted / Q000379:methods*; D013977:Tibia / Q000473:pathology / Q000601:surgery; D014057:Tomography, X-Ray Computed