title: Does varus alignment adversely affect implant survival and function six years after kinematically aligned total knee arthroplasty?
abstract: OBJECTIVE
  We report the six year implant survivorship, tibial component alignment and knee and limb function measured by the Oxford Knee Score and Western Ontario and McMaster Universities Osteoarthritis Index ((WOMAC) score after kinematically aligned total knee arthroplasty (TKA) and tested the hypothesis that varus alignment of the tibial component, knee, or limb does not adversely affect implant survival and function.
  
  
  METHODS
  We prospectively followed 214 consecutive patients (219 knees) treated with a kinematically aligned TKA in 2007. Kaplan-Meier survival analysis and revision rate per 100 component years determined implant failure. The Oxford Knee Score (0 worst, 48 best) and WOMAC score (0 worst, 100 best) were used to measure function. We categorised tibial component alignment as in-range (≤ 0°) or varus (>0°), knee alignment as in-range (between -2.5° and -7.4°), varus (>-2.5°), or valgus (<-7.4°), and limb alignment as in-range (0° ± 3°), varus (>3°) or valgus (<-3°).
  
  
  RESULTS
  At a mean of 6.3 years (range, 5.8-7.2), implant survivorship was 97.5 % and revision-rate per 100 component years 0.40. Three implants had been revised (deep infection one, loose tibial component one and patella instability [1); two loose patella components were pending revision and considered failures. The average Oxford Knee Score was 43 and WOMAC 91. Function of tibial components (80 %), knees (31 %) and limbs (7 %) that were aligned in varus was similar to patients aligned in-range.
  
  
  CONCLUSIONS
  At a mean of 6.3 years after kinematically aligned TKA, varus alignment of the tibial component, knee and limb did not adversely affect implant survival or function, which supports the consideration of kinematic alignment as an alternative to mechanical alignment for performing primary TKA. Level of evidence, III; therapeutic study.
authors.affiliation: Biomedical Engineering Graduate Group, University of California, Davis, Davis, CA, 95616, USA. sebhowell@mac.com.|Department of Mechanical Engineering, University of California, Davis, Davis, CA, 95616, USA. sebhowell@mac.com.|, 8120 Timberlake Way Ste 112, Sacramento, CA, 95823, USA. sebhowell@mac.com.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Howell
authors.affiliation: Biomedical Engineering Graduate Group, University of California, Davis, Davis, CA, 95616, USA.|Department of Mechanical Engineering, University of California, Davis, Davis, CA, 95616, USA.|Department of Biomedical Engineering, University of California, Davis, Davis, CA, 95616, USA.|, 8120 Timberlake Way Ste 112, Sacramento, CA, 95823, USA.
authors.forename: Stelios
authors.initials: S
authors.lastname: Papadopoulos
authors.affiliation: Biomedical Engineering Graduate Group, University of California, Davis, Davis, CA, 95616, USA.|Department of Mechanical Engineering, University of California, Davis, Davis, CA, 95616, USA.|Department of Biomedical Engineering, University of California, Davis, Davis, CA, 95616, USA.|, 8120 Timberlake Way Ste 112, Sacramento, CA, 95823, USA.
authors.forename: Kyle
authors.initials: K
authors.lastname: Kuznik
authors.affiliation: Biomedical Engineering Graduate Group, University of California, Davis, Davis, CA, 95616, USA.|Department of Mechanical Engineering, University of California, Davis, Davis, CA, 95616, USA.|Department of Biomedical Engineering, University of California, Davis, Davis, CA, 95616, USA.|, 8120 Timberlake Way Ste 112, Sacramento, CA, 95823, USA.
authors.forename: Lillian R
authors.initials: LR
authors.lastname: Ghaly
authors.affiliation: Biomedical Engineering Graduate Group, University of California, Davis, Davis, CA, 95616, USA.|Department of Mechanical Engineering, University of California, Davis, Davis, CA, 95616, USA.|Department of Biomedical Engineering, University of California, Davis, Davis, CA, 95616, USA.
authors.forename: Maury L
authors.initials: ML
authors.lastname: Hull
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects* / Q000379:methods; D001696:Biomechanical Phenomena; D005260:Female; D056305:Genu Varum / Q000601:surgery*; D006801:Humans; D053208:Kaplan-Meier Estimate; D007719:Knee Joint / Q000601:surgery*; D007720:Knee Prosthesis / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D010329:Patella / Q000601:surgery; D011446:Prospective Studies; D012086:Reoperation; D013977:Tibia / Q000601:surgery
keywords: Alignment; Arthroplasty; Kinematic; Knee; Survival
references.citation: Int Orthop. 2015 Mar;39(3):455-60
references.pmid: 25242460
references.citation: J Bone Joint Surg Am. 2013 Jan 16;95(2):126-31
references.pmid: 23324959
references.citation: Knee Surg Sports Traumatol Arthrosc. 2013 Oct;21(10 ):2271-80
references.pmid: 23948721
references.citation: Bone Joint J. 2013 Jan;95-B(1):45-51
references.pmid: 23307672
references.citation: Clin Orthop Relat Res. 2012 Mar;470(3):895-902
references.pmid: 22183477
references.citation: Knee Surg Sports Traumatol Arthrosc. 2015 Aug;23(8):2159-69
references.pmid: 24705849
references.citation: Orthopedics. 2012 Feb 17;35(2):e160-9
references.pmid: 22310400
references.citation: Arch Orthop Trauma Surg. 2010 Dec;130(12 ):1487-91
references.pmid: 20165859
references.citation: Bone Joint J. 2014 Jul;96-B(7):907-13
references.pmid: 24986944
references.citation: J Bone Joint Surg Br. 1991 Sep;73(5):709-14
references.pmid: 1894655
references.citation: J Bone Joint Surg Br. 2010 Apr;92(4):508-12
references.pmid: 20357326
references.citation: Clin Orthop Relat Res. 2010 Apr;468(4):1142-8
references.pmid: 19623495
references.citation: J Bone Joint Surg Am. 2011 Dec 21;93 Suppl 3:55-61
references.pmid: 22262425
references.citation: J Orthop Res. 2014 Mar;32(3):394-402
references.pmid: 24281940
references.citation: Orthopedics. 2008 Sep;31(9):857-63
references.pmid: 18814593
references.citation: Can J Surg. 2005 Apr;48(2):100-5
references.pmid: 15887788
references.citation: J Bone Joint Surg Am. 2010 Sep 15;92(12):2143-9
references.pmid: 20844155
references.citation: J Bone Joint Surg Am. 2011 Sep 7;93(17):1588-96
references.pmid: 21915573
references.citation: Clin Orthop Relat Res. 2013 Mar;471(3):1000-7
references.pmid: 22996362
references.citation: Knee Surg Sports Traumatol Arthrosc. 2013 Oct;21(10 ):2325-30
references.pmid: 23552665
references.citation: Bone Joint J. 2014 Nov;96-B(11 Supple A):96-100
references.pmid: 25381418
references.citation: Int Orthop. 2015 Mar;39(3):461-6
references.pmid: 25300395
references.citation: Knee Surg Sports Traumatol Arthrosc. 2013 Oct;21(10):2281-7
references.pmid: 23052114
references.citation: J Bone Joint Surg Am. 2014 Jun 18;96(12 ):e101
references.pmid: 24951744
references.citation: Int Orthop. 2014 Feb;38(2):457-63
references.pmid: 24305791