title: The extensor hallucis longus tendon as the distal reference point in total knee arthroplasty and tibial alignment.
abstract: OBJECTIVE
  The aim of this study was to compare the effects on tibial alignment of the use of the extensor hallucis longus (EHL) tendon with the use of the 2nd metatarsal as a reference in total knee arthroplasty (TKA) using the extramedullary technique.
  
  
  METHODS
  The study evaluated 100 postoperative radiographs of 79 patients who underwent primary TKA between 2004 and 2008. Patients were grouped according to the distal anatomical landmark used during surgery. There were 36 patients (mean age: 68.3 years, range: 56 to 82 years) in the EHL-referenced (ERT) group and 43 patients (mean age: 70.2 years, range: 54 to 78 years) in the 2nd metatarsal-referenced (MRT) group. There were 47 components in the ERT group and 53 in the MRT group. Frontal alignments of the tibial components were measured. Angles of 90±2° were accepted as the normal boundaries while those above that value were labeled as 'varus' and those below as 'valgus'.
  
  
  RESULTS
  Average frontal alignment was 88.57° in the MRT group and 89.17° in the ERT group. The number of tibial components in the normal range was significantly higher (p=0.017) and the number of varus-oriented components significantly lower (p=0.024) in the ERT group. There were no significant differences in valgus-oriented outliers between groups (p=1.000).
  
  
  CONCLUSIONS
  The use of the EHL tendon as a reference improves coronal tibial alignment. The EHL is a reliable anatomical landmark to use with extramedullary guide systems.
authors.affiliation: Department of Orthopedics and Traumatology, Uludağ University, Faculty of Medicine, Bursa, Turkey.
authors.forename: Omer
authors.initials: O
authors.lastname: Bilgen
authors.affiliation: Department of Orthopedics and Traumatology, Uludağ University, Faculty of Medicine, Bursa, Turkey.
authors.forename: Sadık
authors.initials: S
authors.lastname: Bilgen
authors.affiliation: Department of Orthopedics and Traumatology, İstanbul Training and Research Hospital, İstanbul, Turkey.
authors.forename: Cenk
authors.initials: C
authors.lastname: Ermutlu
authors.affiliation: Department of Orthopedics and Traumatology, Çanakkale Onsekiz Mart University, Faculty of Medicine, Çanakkale, Turkey.
authors.forename: Ferdi
authors.initials: F
authors.lastname: Göksel
authors.affiliation: Department of Orthopedics and Traumatology, Uludağ University, Faculty of Medicine, Bursa, Turkey.
authors.forename: Necmettin
authors.initials: N
authors.lastname: Salar
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D017760:Bone Malalignment / Q000517:prevention & control*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012189:Retrospective Studies; D013709:Tendon Transfer; D013977:Tibia / Q000000981:diagnostic imaging / Q000601:surgery*; D014034:Toes / Q000601:surgery; D016896:Treatment Outcome