title: Patient specific guides for total knee arthroplasty are ready for primetime.
abstract: OBJECTIVE
  To present the radiological results of total knee arthroplasty (TKA) with use of patient specific matched guides (PSG) from different manufacturer in patients suffering from severe osteoarthritis of the knee joint.
  
  
  METHODS
  This study describes the results of 57 knees operated with 4 different PSG systems and a group operated with conventional instrumentation (n = 60) by a single surgeon. The PSG systems were compared with each other and subdivided into cut- and pin PSG. The biomechanical axis [hip-knee-ankle angle (HKA)], varus/valgus of the femur [frontal femoral component (FFC)] and tibia (frontal tibial component) component, flexion/extension of the femur [flexion/extension of the femur component (LFC)] and posterior slope of the tibia [lateral tibial component (LTC)] component were evaluated on long-leg standing and lateral X-rays. A percentage of > 3(°) deviation was seen as an outlier.
  
  
  RESULTS
  The inter class correlation coefficient (ICC) revealed that radiographic measurements between both assessors were reliable (ICC > 0.8). Fisher exact test was used to test differences of proportions. The percentage of outliers of the HKA-axis was comparable between both the PSG and conventional groups (12.28% vs 18.33%, P < 0.424) and the cut- and pin PSG groups (14.3% vs 10.3%, P < 1.00). The percentage of outliers of the FFC (0% vs 18.33%, P < 0.000), LFC (15.78% vs 58.33%, P < 0.000) and LTC (15.78% vs 41.67%, P < 0.033) were significant different in favour of the PSG group. There were no significant differences regarding the outliers between the individual PSG systems and the PSG group subdivided into cut- and pin PSG.
  
  
  CONCLUSIONS
  PSG for TKA show significant less outliers compared to the conventional technique. These single surgeon results suggest that PSG are ready for primetime.
authors.affiliation: Martijn GM Schotanus, Bert Boonen, Nanne P Kort, Department of Orthopaedic Surgery, Zuyderland Medical Centre, 6162 BG Sittard-Geleen, The Netherlands.
authors.forename: Martijn Gm
authors.initials: MG
authors.lastname: Schotanus
authors.affiliation: Martijn GM Schotanus, Bert Boonen, Nanne P Kort, Department of Orthopaedic Surgery, Zuyderland Medical Centre, 6162 BG Sittard-Geleen, The Netherlands.
authors.forename: Bert
authors.initials: B
authors.lastname: Boonen
authors.affiliation: Martijn GM Schotanus, Bert Boonen, Nanne P Kort, Department of Orthopaedic Surgery, Zuyderland Medical Centre, 6162 BG Sittard-Geleen, The Netherlands.
authors.forename: Nanne P
authors.initials: NP
authors.lastname: Kort
keywords: Alignment; Conventional instruments; Cutting guides; Patient matched instruments; Patient specific matched guides; Pin guides; Single surgeon; Total knee arthroplasty