title: Margin of error in alignment: a study undertaken when converting from conventional to computer-assisted total knee arthroplasty.
abstract: We analyzed alignment of 300 knees, divided equally into groups according to total knee arthroplasty technique: Conventional, CAS-Early (computer-assisted surgery during the surgeon's learning curve), and CAS-Late (after experience with CAS). With the margin of error for alignment of the mechanical axis and femoral and tibial components each within ±3°, the Conventional group's success rate was only 66%; but the rate for the CAS-Early group was 94%. The CAS-Late group's rate was 100%, with no outliers; moreover, the margin of error was reduced to within ±2° in 92% of patients and within ±1° in 52%. For the Conventional group's success rate to be 100%, the margin of error would have to be statistically relaxed to an unacceptable ±8°. Computed-assisted surgery improves alignment even early in the learning curve.
authors.affiliation: Department of Orthopaedic Surgery, Lilavati Hospital & Research Centre, Mumbai, India.
authors.forename: Rajesh N
authors.initials: RN
authors.lastname: Maniar
authors.forename: Ajay C
authors.initials: AC
authors.lastname: Johorey
authors.forename: Chandrashekhar T
authors.initials: CT
authors.lastname: Pujary
authors.forename: Akhilesh N
authors.initials: AN
authors.lastname: Yadava
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001696:Biomechanical Phenomena; D017760:Bone Malalignment / Q000000981:diagnostic imaging / Q000517:prevention & control*; D003627:Data Interpretation, Statistical; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000502:physiology / Q000601:surgery; D059032:Learning Curve; D008297:Male; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology; D012189:Retrospective Studies; D025321:Surgery, Computer-Assisted / Q000379:methods*; D013977:Tibia / Q000000981:diagnostic imaging / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome