title: A comparison of alignment using patient specific guides, computer navigation and conventional instrumentation in total knee arthroplasty.
abstract: BACKGROUND
  Patient specific guides (PSG) have been introduced as a tool in total knee arthroplasty (TKA) in an attempt to improve limb alignment and reduce operative time compared to other established surgical techniques. The purpose of this study was to compare the post-operative radiographic alignment and operative time in patients who underwent TKA surgery with PSG, conventional instrumentation or computer-assisted navigation surgery using fully cemented components.
  
  
  METHODS
  A cohort of 260 patients who underwent TKA surgery using PSG (PSG group, n=115) was compared to patients who underwent TKA using either conventional instrumentation (CON group, n=92) or computer-assisted navigation (CAS group, n=53). Post-operative CT imaging using the Perth CT protocol was used to compare alignment between the three groups.
  
  
  RESULTS
  In the PSG and CAS groups, the post-operative hip-knee angle (HKA) was within 3° of neutral alignment in 91.3% and 90.7% of patients, respectively. This compared to 80.4% of patients in the CON group (p=0.02). There were no significant differences with respect to alignment when comparing individual component positioning between the PSG and CAS groups apart from tibial slope (Table 3). Total operative time was found to be significantly reduced in the PSG group (80.2 min) compared to both the CON group (86 min, p=0.002) and the CAS group (110.2 min, p<0.0001).
  
  
  CONCLUSIONS
  The use of PSG resulted in similar alignment accuracy to CAS and superior alignment to CON with significantly shorter operative times.
authors.affiliation: Sydney Knee Specialists, St George Private Hospital, Sydney, NSW, Australia. Electronic address: samuelmacdessi@sydneyknee.com.au.
authors.forename: Samuel J
authors.initials: SJ
authors.lastname: MacDessi
authors.affiliation: Sydney Knee Specialists, St George Private Hospital, Sydney, NSW, Australia.
authors.forename: Bob
authors.initials: B
authors.lastname: Jang
authors.affiliation: South Western Sydney Clinical School, University of New South Wales, Australia.
authors.forename: Ian A
authors.initials: IA
authors.lastname: Harris
authors.affiliation: Bryant Radiology, St George Private Hospital, Sydney, NSW, Australia.
authors.forename: Emma
authors.initials: E
authors.lastname: Wheatley
authors.affiliation: Bryant Radiology, St George Private Hospital, Sydney, NSW, Australia.
authors.forename: Carl
authors.initials: C
authors.lastname: Bryant
authors.affiliation: Sydney Knee Specialists, St George Private Hospital, Sydney, NSW, Australia.
authors.forename: Darren B
authors.initials: DB
authors.lastname: Chen
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D015331:Cohort Studies; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000601:surgery; D007720:Knee Prosthesis; D061646:Operative Time; D017755:Prosthesis Fitting; D011859:Radiography; D025321:Surgery, Computer-Assisted
keywords: Alignment; Conventional; Patient specific guides