title: Fibular axes are not a reliable landmark for tibial mechanical axes of osteoarthritic knees that underwent total knee arthroplasty.
abstract: OBJECTIVE
  The sagittal fibular axis serves as an intra-operative landmark during conventional total knee arthroplasty (TKA); however, only a few relevant anatomical studies have been published regarding its use as an extramedullary guide. Furthermore, the correlation between the coronal fibular and tibial mechanical axes in osteoarthritic knees has been only reported once. Here, the hypothesis of this study is that the fibula can be a reliable intra-operative landmark, in the sagittal and coronal planes, among patients with osteoarthritis who have undergone TKA.
  
  
  METHODS
  Osteoarthritic knees (n = 62) after TKA were evaluated using three-dimensional image-matching software. The angles between the tibial mechanical axis and the fibular shaft axis were measured in the sagittal and coronal planes. Moreover, correlations between the angles and patient-specific factors were evaluated.
  
  
  RESULTS
  The mean angle between the tibial mechanical and fibular shaft axes was 2.6° ± 2.3° for posterior inclination in the sagittal plane and 0.9° ± 2.0° for varus inclination in the coronal plane. The percentage of subjects with the fibular shaft axis within 2° of the tibial mechanical axis was 17.7 and 69.3 % in the sagittal and coronal planes, respectively. No patient-specific factors were correlated with the angle between the tibial mechanical and fibular shaft axes.
  
  
  CONCLUSIONS
  The angle between the tibial mechanical and fibular shaft axes differed among patients, independent of patient-specific factors, and did not appear to be a reliable intra-operative landmark. Surgeons should use values from individual pre-operative evaluations of the axis as reference for conventional TKA.
  
  
  METHODS
  Case series with no comparison group, Level IV.
authors: Department of Orthopaedic Surgery, Hyogo Rehabilitation Center Hospital, Kobe, Japan.
authors: Yuichi
authors: Y
authors: Kuroda
authors: Department of Orthopaedic Surgery, Kobe Kaisei Hospital, 3-11-15, Shinohara-Kita, Nada, Kobe, 657-0068, Japan. wavedreamer17@yahoo.co.jp.
authors: Kazunari
authors: K
authors: Ishida
authors: Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors: Tomoyuki
authors: T
authors: Matsumoto
authors: Department of Orthopaedic Surgery, Kobe Kaisei Hospital, 3-11-15, Shinohara-Kita, Nada, Kobe, 657-0068, Japan.
authors: Hiroshi
authors: H
authors: Sasaki
authors: Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors: Tokio
authors: T
authors: Matsuzaki
authors: Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors: Shinya
authors: S
authors: Oka
authors: Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors: Koji
authors: K
authors: Takayama
authors: Department of Orthopaedic Surgery, Chibune General Hospital, Osaka, Japan.
authors: Katsumasa
authors: K
authors: Tei
authors: Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors: Takehiko
authors: T
authors: Matsushita
authors: Department of Orthopaedic Surgery, Hyogo Rehabilitation Center Hospital, Kobe, Japan.
authors: Nobuhiro
authors: N
authors: Tsumura
authors: Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors: Ryosuke
authors: R
authors: Kuroda
authors: Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors: Masahiro
authors: M
authors: Kurosaka
mesh_terms: D000368:Aged; D059925:Anatomic Landmarks; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D005260:Female; D005360:Fibula / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D006801:Humans; D021621:Imaging, Three-Dimensional; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D020370:Osteoarthritis, Knee / Q000601:surgery*; D011859:Radiography; D012984:Software; D013977:Tibia / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery
keywords: Anatomical landmark; Fibula axis; Surgical technique; Tibial slope; Total knee arthroplasty