title: Inter-observer precision and physiologic variability of mri landmarks used to determine rotational alignment in conventional and patient-specific TKA.
abstract: Preoperative planning for patient-specific guides (PSGs) in total knee arthroplasty (TKA) requires identification of anatomic landmarks on three-dimensional imaging studies. The aim of this study was to assess the accuracy and precision with which landmarks commonly used to determine rotational alignment in TKA can be identified on magnetic resonance imaging (MRI). Two orthopedic surgeons and two musculoskeletal radiologists independently reviewed a sequential series of 114 MRIs of arthritic knees. The magnitude of interobserver variability was high, suggesting an inherent risk of inconsistency when these landmarks are used in PSG fabrication. Additionally, there was a high degree of physiologic variation among patients, indicating that assuming standard relationships among anatomic landmarks when placing TKA components may lead to rotational malalignment relative to each patient's native anatomy.
authors.affiliation: Department of Orthopaedic Surgery, Barnes Jewish Hospital, St. Louis, Missouri.
authors.forename: Andrew
authors.initials: A
authors.lastname: Park
authors.affiliation: Department of Orthopaedic Surgery, Barnes Jewish Hospital, St. Louis, Missouri.
authors.forename: Denis
authors.initials: D
authors.lastname: Nam
authors.affiliation: Musculoskeletal Radiology Section, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Michael V
authors.initials: MV
authors.lastname: Friedman
authors.affiliation: Department of Orthopaedic Surgery, Barnes Jewish Hospital, St. Louis, Missouri.
authors.forename: Stephen T
authors.initials: ST
authors.lastname: Duncan
authors.affiliation: Musculoskeletal Radiology Section, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Travis J
authors.initials: TJ
authors.lastname: Hillen
authors.affiliation: Department of Orthopaedic Surgery, Barnes Jewish Hospital, St. Louis, Missouri.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Barrack
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D059925:Anatomic Landmarks; D001168:Arthritis / Q000175:diagnosis* / Q000601:surgery; D019645:Arthroplasty, Replacement, Knee; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D007719:Knee Joint / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012189:Retrospective Studies; D012399:Rotation; D025321:Surgery, Computer-Assisted
keywords: anatomic landmarks in TKA; malrotation; patient-specific TKA; physiologic variability; rotational alignment