title: Improved alignment and operating room efficiency with patient-specific instrumentation for TKA.
abstract: BACKGROUND
  Achieving accurate alignment in total knee arthroplasty (TKA) remains a concern. Patient-specific instrumentation (PSI) produced using preoperative 3D models was developed to offer surgeons a simplified, reliable, efficient and customised TKA procedure.
  
  
  METHODS
  In this prospective study, 60 patients underwent TKA with conventional instrumentation and 71 patients were operated on using PSI. The primary endpoint was surgical time. Secondary endpoints included operating room (OR) time, the number of instrument trays used and postoperative radiographic limb alignment.
  
  
  RESULTS
  Compared to conventional instrumentation, PSI significantly reduced total surgical time by 8.9 ± 3.3 min (p=0.038), OR time by 8.6 ± 4.2 min (p=0.043), and the number of instrument trays by six trays (p<0.001). Mechanical axis malalignment of the lower limb of >3° was observed in 13% of PSI patients versus 29% with conventional instrumentation (p=0.043). PSI predicted the size of the femoral and tibial components actually used in 85.9% and 78.9% of cases, respectively.
  
  
  CONCLUSIONS
  PSI improves alignment, surgical and OR time, reduces the number of instruments trays used compared to conventional instrumentation in patients undergoing TKA and results in fewer outliers in overall mechanical alignment in the coronal plane.
  
  
  METHODS
  Prospective comparative therapeutic study.
authors.affiliation: RZ St. Trudo Hospital, Department of Orthopaedics and Traumatology, 3800 Sint-Truiden, Belgium. Electronic address: lucrenson@telenet.be.
authors.forename: Luc
authors.initials: L
authors.lastname: Renson
authors.affiliation: Hôpital de Braine l'Alleud-Waterloo, 1420 Braine l'Alleud, Belgium.
authors.forename: Pascal
authors.initials: P
authors.lastname: Poilvache
authors.affiliation: AZ Alma Campus Sijsele, Department of Orthopaedics and Traumatology, Sijsele, 8340 Damme, Belgium.
authors.forename: Hans
authors.initials: H
authors.lastname: Van den Wyngaert
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation*; D017076:Computer-Aided Design; D017598:Efficiency, Organizational; D006801:Humans; D021621:Imaging, Three-Dimensional; D007720:Knee Prosthesis; D009873:Operating Rooms / Q000458:organization & administration*; D061646:Operative Time; D066230:Patient-Specific Modeling / Q000706:statistics & numerical data*; D057285:Precision Medicine / Q000379:methods; D011446:Prospective Studies; D011474:Prosthesis Design; D014102:Torsion Abnormality / Q000517:prevention & control; D016896:Treatment Outcome
keywords: Alignment; Patient-matched instrumentation; Patient-specific guides; Patient-specific instruments; Total knee arthroplasty