title: Component alignment and clinical outcome following total knee arthroplasty: a randomised controlled trial comparing an intramedullary alignment system with patient-specific instrumentation.
abstract: OBJECTIVE
  We conducted a randomised controlled trial to assess the accuracy of positioning and alignment of the components in total knee arthroplasty (TKA), comparing those undertaken using standard intramedullary cutting jigs and those with patient-specific instruments (PSI).
  
  
  METHODS
  There were 64 TKAs in the standard group and 69 in the PSI group. The post-operative hip-knee-ankle (HKA) angle and positioning was investigated using CT scans. Deviation of > 3° from the planned position was regarded as an outlier. The operating time, Oxford Knee Scores (OKS) and Short Form-12 (SF-12) scores were recorded.
  
  
  RESULTS
  There were 14 HKA-angle outliers (22%) in the standard group and nine (13%) in the PSI group (p = 0.251). The mean HKA-angle was 0.5° varus in the standard group and 0.2° varus in the PSI group (p = 0.492). The accuracy of alignment in the coronal and axial planes and the proportion of outliers was not different in the two groups. The femoral component was more flexed (p = 0.035) and there were significantly more tibial slope outliers (29% versus 13%) in the PSI group (p = 0.032). Operating time and the median three-month OKS were similar (p = 0.218 and p = 0.472, respectively). Physical and mental SF-12 scores were not significantly different at three months (p = 0.418 and p = 0.267, respectively) or at one year post-operatively (p = 0.114 and p = 0.569). The median one-year Oxford knee score was two points higher in the PSI group (p = 0.049).
  
  
  CONCLUSIONS
  Compared with standard intramedullary jigs, the use of PSI did not significantly reduce the number of outliers or the mean operating time, nor did it clinically improve the accuracy of alignment or the median Oxford Knee Scores. Our data do not support the routine use of PSI when undertaking TKA. Cite this article: Bone Joint J 2016;98-B:1043-9.
authors.affiliation: The Joint Studio, Hollywood Medical Centre, 1/85 Monash Ave, Nedlands, WA, Australia.
authors.forename: H J T A M
authors.initials: HJ
authors.lastname: Huijbregts
authors.affiliation: The Joint Studio, Hollywood Medical Centre, 85 Monash Avenue, Nedlands, WA 6009, Australia.
authors.forename: R J K
authors.initials: RJ
authors.lastname: Khan
authors.affiliation: The Joint Studio, Hollywood Medical Centre, 85 Monash Avenue, Nedlands, WA 6009, Australia.
authors.forename: D P
authors.initials: DP
authors.lastname: Fick
authors.affiliation: The Joint Studio, Hollywood Medical Centre, 85 Monash Avenue, Nedlands, WA 6009, Australia.
authors.forename: M J
authors.initials: MJ
authors.lastname: Hall
authors.affiliation: The Joint Studio, Hollywood Medical Centre, 85 Monash Avenue, Nedlands, WA 6009, Australia.
authors.forename: S A
authors.initials: SA
authors.lastname: Punwar
authors.affiliation: Geraldton Regional Hospital, 51-85 Shenton Street, Geraldton WA 6530, Australia.
authors.forename: E
authors.initials: E
authors.lastname: Sorensen
authors.affiliation: The Joint Studio, Hollywood Medical Centre, 85 Monash Avenue, Nedlands, WA 6009, Australia.
authors.forename: M J
authors.initials: MJ
authors.lastname: Reid
authors.affiliation: Geraldton Radiology, Hermitage Street, Geraldton, WA 6530, Australia.
authors.forename: S Dalle
authors.initials: SD
authors.lastname: Vedove
authors.affiliation: The Joint Studio, Hollywood Medical Centre, 85 Monash Avenue, Nedlands, WA 6009, Australia.
authors.forename: S
authors.initials: S
authors.lastname: Haebich
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D001172:Arthritis, Rheumatoid / Q000601:surgery*; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation* / Q000379:methods; D017760:Bone Malalignment / Q000517:prevention & control*; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D061646:Operative Time; D020370:Osteoarthritis, Knee / Q000601:surgery*; D011183:Postoperative Complications / Q000517:prevention & control*; D012720:Severity of Illness Index; D016896:Treatment Outcome
keywords: Operation time; Oxford Knee Score; Patient-matched instrumentation; Patient-specific instrumentation; Total knee arthroplasty