title: Patient-specific total knee arthroplasty required frequent surgeon-directed changes.
abstract: BACKGROUND
  Patient-specific instrumentation potentially improves surgical precision and decreases operative time in total knee arthroplasty (TKA) but there is little supporting data to confirm this presumption.
  
  
  OBJECTIVE
  We asked whether patient-specific instrumentation would require infrequent intraoperative changes to replicate a single surgeon's preferences during TKA and whether patient-specific instrumentation guides would fit securely.
  
  
  METHODS
  We prospectively evaluated the plan and surgery in 60 patients treated with 66 TKAs performed with patient-specific instrumentation and recorded any changes. A subset of six postoperative radiographic changes to the femoral and tibial components (implant size, coronal and sagittal alignment) was analyzed to determine if surgeon intervention was beneficial. Each guide was evaluated to determine fit. We compared patient demographics and implant sizing in the patient-specific instrumentation group with a control group in which traditional instrumentation was used.
  
  
  RESULTS
  We recorded 161 intraoperative changes in 66 knee arthroplasties (2.4 changes/knee) performed with patient-specific instrumentation. The predetermined implant size was changed intraoperatively in 77% of femurs and 53% of tibias. We identified a subset of 95 intraoperative changes that could be radiographically evaluated to determine if our changes were an improvement or detriment to reaching goal alignment. Eighty-two of the 95 changes (86%) made by the surgeon were an improvement to the recommended alignment or size of patient-specific instrumentation. The guide did not fit securely on eight femurs (12%) and three tibias (5%). Tourniquet time and blood loss were not improved with patient-specific instrumentation.
  
  
  CONCLUSIONS
  We caution surgeons against blind acceptance of patient-specific instrumentation technology without supportive data.
authors.affiliation: Department of Orthopaedic Surgery, University of Mississippi Medical Center, Jackson, MS, USA.
authors.forename: Benjamin M
authors.initials: BM
authors.lastname: Stronach
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Pelt
authors.forename: Jill
authors.initials: J
authors.lastname: Erickson
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Peters
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation* / Q000379:methods*; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000601:surgery; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D061646:Operative Time; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000601:surgery*; D057285:Precision Medicine; D011446:Prospective Studies; D017755:Prosthesis Fitting; D011859:Radiography; D012189:Retrospective Studies; D025321:Surgery, Computer-Assisted / Q000295:instrumentation; D016896:Treatment Outcome