title: Variability in the relationship between the distal femoral mechanical and anatomical axes in patients undergoing primary total knee arthroplasty.
abstract: Currently, an intramedullary (IM) guide is often used for performing the distal femoral resection in total knee arthroplasty (TKA). However, this method assumes that in most patients, the distal femoral mechanical-anatomical angle (FMAA) is 5°. Preoperative, standing, AP hip-to-ankle radiographs were reviewed in 493 patients undergoing primary TKA, and the FMAA was digitally measured. Correlation coefficients relative to several radiographic measurements, along with demographic variables, were performed. A significant number of patients (28.6%) had an FMAA outside the range of 5° ± 2° (range 2.0°-9.6°). The only measurement demonstrating a fair/moderate correlation with the FMAA was the neck-shaft angle (r = -0.55). Using an IM resection guide, without obtaining AP hip-to-ankle radiographs to determine each patient's true FMAA, may lead to malalignment of the femoral component.
authors: Department of Orthopaedic Surgery, Adult Reconstruction and Joint Replacement Service, Hospital for Special Surgery, Weill Medical College of Cornell University, New York, New York 10021, USA.
authors: Denis
authors: D
authors: Nam
authors: Patrick A
authors: PA
authors: Maher
authors: Alex
authors: A
authors: Robles
authors: Alexander S
authors: AS
authors: McLawhorn
authors: David J
authors: DJ
authors: Mayman
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001696:Biomechanical Phenomena; D005260:Female; D005269:Femur / Q000033:anatomy & histology* / Q000502:physiology*; D006615:Hip / Q000000981:diagnostic imaging; D006801:Humans; D007866:Leg / Q000000981:diagnostic imaging; D008297:Male; D011859:Radiography; D012189:Retrospective Studies