title: Measuring long radiographs affects the positioning of femoral components in total knee arthroplasty: a randomized controlled trial.
abstract: BACKGROUND
  The aim of this study was to investigate if preoperative measurements of the femoral valgus angle (FVA) affected the mechanical alignment, individual component positions and clinical outcome in total knee arthroplasty (TKA).
  
  
  METHODS
  120 patients were randomized into two groups. In one group (control), a fixed FVA for the intramedullary femoral guide was set at 7°, whereas in the other group (measured) FVA was measured preoperatively on long hip-knee-ankle radiographs, and the angle for the distal femoral cut was set accordingly. Preoperatively and 1 year after TKA, range of motion (ROM) and Knee Society Score (KSS) were assessed. Postoperatively, the coronal alignments of the components and the mechanical alignment were measured comparing the rate of outliers which deviated more than 3° from the neutral mechanical axis.
  
  
  RESULTS
  104 patients remained for the radiological analysis (52 in each group). There were no significant differences either in the mean preoperative or postoperative mechanical alignment, or femoral or tibial component alignment; also, there were no differences in the number of postoperative mechanical axis or tibial component alignment outliers. However, the number of femoral component alignment outliers was significantly higher in the control group. 97 patients were available for clinical outcome analysis. Preoperatively, the groups did not differ significantly with respect to KSS or ROM. The postoperative ROM and KSS functional subscale scores were similar between the groups. However, there was slightly but significantly better postoperative KSS objective subscale score in the measured group.
  
  
  CONCLUSIONS
  Preoperative FVA measurement and following femoral distal cut adjustments did not affect overall leg alignment postoperatively, while positioning of femoral component was improved together with minor improvements in objective KSS subscale scores.
authors.affiliation: Department of Orthopaedics, Lithuanian University of Health Sciences, Eiveniu 2, 50009, Kaunas, Lithuania. justinas.stucinskas@lsmuni.lt.
authors.forename: Justinas
authors.initials: J
authors.lastname: Stucinskas
authors.affiliation: Department of Clinical Sciences, Lund University, Lund, Sweden.|Department of Orthopaedics, Lund University and Lund University Hospital, Lund, Sweden.
authors.forename: Otto
authors.initials: O
authors.lastname: Robertsson
authors.affiliation: Department of Orthopaedics, Lithuanian University of Health Sciences, Eiveniu 2, 50009, Kaunas, Lithuania.
authors.forename: Aleksej
authors.initials: A
authors.lastname: Lebedev
authors.affiliation: Department of Clinical Sciences, Lund University, Lund, Sweden.|Department of Orthopaedics, Lund University and Lund University Hospital, Lund, Sweden.
authors.forename: Hans
authors.initials: H
authors.lastname: Wingstrand
authors.affiliation: Department of Orthopaedics, Lithuanian University of Health Sciences, Eiveniu 2, 50009, Kaunas, Lithuania.
authors.forename: Alfredas
authors.initials: A
authors.lastname: Smailys
authors.affiliation: Department of Orthopaedics, Lithuanian University of Health Sciences, Eiveniu 2, 50009, Kaunas, Lithuania.
authors.forename: Sarunas
authors.initials: S
authors.lastname: Tarasevicius
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000842:Ankle / Q000000981:diagnostic imaging; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000601:surgery; D006801:Humans; D007717:Knee / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery*; D011446:Prospective Studies; D011859:Radiography; D016059:Range of Motion, Articular; D013977:Tibia / Q000000981:diagnostic imaging / Q000601:surgery; D016896:Treatment Outcome
keywords: Alignment; Arthroplasty; Knee; Mechanical axis