title: Computer assisted versus conventional total knee replacement: a comparison of tourniquet time, blood loss and length of stay.
abstract: AIMS AND INTRODUCTION: The aim of this study was to assess whether navigated total knee arthroplasty (TKA) reduces peri-operative blood loss and post-operative length of stay when compared to conventional total knee arthroplasty techniques.
  
  
  METHODS
  A retrospective case-note review of 143 patients undergoing primary elective total knee arthroplasty was carried out. Two surgeons in this institution perform conventional knee arthroplasty using intramedullary alignment with another two surgeons using the computer assisted technique. Blood losses were calculated using the Meunier et al. (2008) [23] method for calculation of peri-operative blood loss. This is based on changes in peri-operative blood indices compared to the patient's theoretical total blood volume which is calculated using the patient's pre-operative height and weight. Tourniquet time and post-operative length of stay for the two techniques of arthroplasty were also recorded.
  
  
  RESULTS
  Sixty eight patients underwent conventional TKA and 75 patients had navigated TKA's performed. This data showed no significant difference in blood loss (p=0.56) or post-operative length of stay (p=0.36). A significant difference in tourniquet time between the two techniques was demonstrated (p=0.01).
  
  
  CONCLUSIONS
  In this study there was no significant reduction in post-operative length of stay and peri-operative blood loss when using computer-assisted techniques. There was an increase in tourniquet time with the computer-assisted technique that may have implications upon work productivity for primary cemented knee arthroplasty.
authors.affiliation: Institution- Royal Bolton NHS Foundation Trust, Minerva Road, Bolton, Lancashire BL4 0JR, United Kingdom. sanilajwani@doctors.org.uk
authors.forename: Sanil H
authors.initials: SH
authors.lastname: Ajwani
authors.forename: Morgan
authors.initials: M
authors.lastname: Jones
authors.forename: Jeremy W
authors.initials: JW
authors.lastname: Jarratt
authors.forename: Gordon J
authors.initials: GJ
authors.lastname: Shepard
authors.forename: William G
authors.initials: WG
authors.lastname: Ryan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D016063:Blood Loss, Surgical / Q000517:prevention & control*; D005260:Female; D005500:Follow-Up Studies; D006489:Hemostatic Techniques / Q000295:instrumentation*; D006801:Humans; D007902:Length of Stay / Q000639:trends; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D025321:Surgery, Computer-Assisted / Q000379:methods*; D013997:Time Factors; D014111:Tourniquets; D016896:Treatment Outcome