title: Patient-specific and intra-operatively modifiable factors assessed by computer navigation predict maximal knee flexion one year after TKA.
abstract: OBJECTIVE
  There are multiple factors affecting maximal knee flexion (MKF) after total knee arthroplasty (TKA). The aim of the study was to investigate whether patient-specific factors (PSF) and surgically modifiable factors (SMF), measured by means of a computer-assisted navigation system, can predict the MKF after TKA.
  
  
  METHODS
  Data from 99 patients collected during a randomized clinical trial were used for this secondary data analysis. The MKF of the patients was measured preoperatively and 1-year post-surgery. Multiple regression analyses were performed to investigate which combination of variables would be the best to predict the 1-year MKF.
  
  
  RESULTS
  When considering SMF alone, the combination of three factors significantly predicted the 1-year MKF (p = 0.001), explaining 22 % of its variation. When considering only PSF, the combination of pre-op MKF and BMI significantly predicted the 1-year MKF (p < 0.001), explaining 23 % of its variation. When considering both groups of potential predictors simultaneously, the combination of five SMF with two PSF significantly predicted the 1-year MKF (p = 0.001), explaining 32 % of its variation.
  
  
  CONCLUSIONS
  Computer navigation variables alone could explain 22 % of the variance in the 1-year MKF. The larger proportion (32 %) of the 1-year MKF variation could be explained with a combination of SMF and PSF. The results of studies in this area could be used to identify patients at risk of poor outcomes.
  
  
  METHODS
  Level II, Prognostic study.
authors.affiliation: Research Center of the Orthopedic and Joint Replacement Department, Schoen Klinik Hamburg Eilbek, Dehnhaide 120, 22081, Hamburg, Germany.|Faculty of Life Sciences, Hamburg University of Applied Sciences, Lohbrügger Kirchstraße 65, 21033, Hamburg, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Lampe
authors.affiliation: Research Center of the Orthopedic and Joint Replacement Department, Schoen Klinik Hamburg Eilbek, Dehnhaide 120, 22081, Hamburg, Germany. cmarques@schoen-kliniken.de.
authors.forename: Carlos J
authors.initials: CJ
authors.lastname: Marques
authors.affiliation: Department of Orthopedics and Joint Replacement, Schoen Klinik Hamburg Eilbek, Dehnhaide 120, 22081, Hamburg, Germany.
authors.forename: Franziska
authors.initials: F
authors.lastname: Fiedler
authors.affiliation: Department of Orthopedics and Joint Replacement, Schoen Klinik Hamburg Eilbek, Dehnhaide 120, 22081, Hamburg, Germany.
authors.forename: Anusch
authors.initials: A
authors.lastname: Sufi-Siavach
authors.affiliation: Mathematic Methods Department, Faculty of Human Kinetics, Lisbon University, Estrada da Costa, 1499-002, Cruz Quebrada, Portugal.
authors.forename: Ana I
authors.initials: AI
authors.lastname: Carita
authors.affiliation: Orthopaedic Department, Jena University Hospital, Campus Eisenberg, Klosterlausnitzer Straße 81, 07607, Eisenberg, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Matziolis
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000601:surgery; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery; D016059:Range of Motion, Articular / Q000502:physiology*; D025321:Surgery, Computer-Assisted
keywords: Computer-assisted surgery; Joint range of motion; Prognosis; Total knee replacement