title: Significant Incidence of Extra-Articular Tibia Vara Affects Radiological Outcome of Total Knee Arthroplasty.
abstract: OBJECTIVE
  To identify and quantify the presence of extra-articular tibia vara that might influence the mechanical axis alignment after total knee arthroplasty (TKA).
  
  
  METHODS
  A total of 48 TKAs in 30 osteoarthritic Indian patients were prospectively evaluated. The hip-knee-ankle angle (HKA), joint line convergence angle, and varus angulation at the femur and tibia were measured from the preoperative and postoperative standing hip-to-ankle radiographs. Four different methods were used to measure the varus angulation at the tibia: metaphyseo-diaphyseal angle (MDA), the angle between the anatomical axis and mechanical axis of the tibia, the angle between the proximal third and distal third of tibia and the angle between the proximal half and distal half of tibia.
  
  
  RESULTS
  Extra-articular tibia vara quantified using MDA had the most positive correlation with HKA. Receiver operating characteristic plotting showed that MDA of >4° predicts abnormal postoperative HKA. Twenty-eight out of 48 knees had MDA of >4°, and 78.6% of these had postoperative HKA under-correction and 21.4% had less than ideal tibial component position.
  
  
  CONCLUSIONS
  A significant inherent extra-articular varus angulation best measured using MDA exists in the proximal tibia in osteoarthritic Indian patients undergoing TKA. MDA of >4° is associated with abnormal postoperative HKA. Computer navigation may be useful for achieving ideal correction in such cases.
authors.affiliation: Department of Orthopaedics, Post Graduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Balaji
authors.initials: B
authors.lastname: Saibaba
authors.affiliation: Department of Orthopaedics, Post Graduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Mandeep S
authors.initials: MS
authors.lastname: Dhillon
authors.affiliation: Department of Orthopaedics, Post Graduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Devendra K
authors.initials: DK
authors.lastname: Chouhan
authors.affiliation: Department of Orthopaedics, Post Graduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Rajendra K
authors.initials: RK
authors.lastname: Kanojia
authors.affiliation: Department of Radiology, Post Graduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Mahesh
authors.initials: M
authors.lastname: Prakash
authors.affiliation: Department of Orthopaedics, Post Graduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Vikas
authors.initials: V
authors.lastname: Bachhal
keywords: Arthroplasty; Indian; Knee; Malalignment; Osteoarthritis; Tibia vara