title: Clinical usefulness of hindfoot assessment for total knee arthroplasty: persistent post-operative hindfoot pain and alignment in pre-existing severe knee deformity.
abstract: OBJECTIVE
  The purpose of this study was to compare the hindfoot alignment and symptoms in patients with pre-existing moderate and severe knee deformities after total knee arthroplasty (TKA).
  
  
  METHODS
  Eighty knees of 75 patients who underwent TKA for varus osteoarthritis were enrolled retrospectively and evaluated the following pre-operatively and at 2 years post-operatively: the American Orthopaedic Foot and Ankle Society ankle-hindfoot scale (pain and function scores), calcaneal pitch, and naviculocuboid overlap as an indicator of hindfoot alignment. The knees were divided into two groups according to the pre-operative hip-knee-ankle angle defined as the angle between the mechanical axis of the femur and the tibia: group M with genu varus of ≤6°, and group S with varus >6°.
  
  
  RESULTS
  The pain (p = 0.03) and function (p = 0.02) scores improved in group M; however, in group S, these measures did not change. The differences between the groups were not significant concerning the pre-operative calcaneal pitch and naviculocuboid overlap. The post-operative pitch (p = 0.03) and the overlap (p = 0.04) in group M was significantly greater and less than those in group S, respectively. Although the pitch (p < 0.01) and the overlap (p = 0.03) increased in group M, these did not change in group S. Post-operative hindfoot pain and valgus remained in patients in group S.
  
  
  CONCLUSIONS
  For pre-existing moderate knee deformities, a relationship was observed between post-operative knee alignment and compensatory hindfoot alignment, whereas patients with severe deformities experienced persistent post-operative hindfoot pain and valgus alignment. It was concluded that evaluations and managements of residual symptoms after TKA including the hindfoot are important. These findings are clinically relevant that perioperative evaluation of the hindfoot should be required in knee surgery. To help improve the outcomes of TKA, clinicians may consider perioperative intervention in the insole and/or physical therapy of the foot and ankle.
  
  
  METHODS
  Therapeutic study, Level III.
authors.affiliation: Department of Orthopedic Surgery, Osaka Medical College, Takatsuki, Osaka, Japan. ort141@osaka-med.ac.jp.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Okamoto
authors.affiliation: Department of Orthopedic Surgery, Osaka Medical College, Takatsuki, Osaka, Japan.
authors.forename: Shuhei
authors.initials: S
authors.lastname: Otsuki
authors.affiliation: Department of Orthopedic Surgery, Osaka Medical College, Takatsuki, Osaka, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Jotoku
authors.affiliation: Department of Orthopedic Surgery, Osaka Medical College, Takatsuki, Osaka, Japan.
authors.forename: Mikio
authors.initials: M
authors.lastname: Nakajima
authors.affiliation: Department of Orthopedic Surgery, Osaka Medical College, Takatsuki, Osaka, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Neo
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000843:Ankle Joint / Q000000981:diagnostic imaging / Q000502:physiology; D019645:Arthroplasty, Replacement, Knee; D002111:Calcaneus / Q000000981:diagnostic imaging / Q000502:physiology; D005260:Female; D005269:Femur / Q000601:surgery; D005528:Foot / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery; D010149:Postoperative Pain / Q000209:etiology*; D011859:Radiography; D012189:Retrospective Studies; D013977:Tibia / Q000601:surgery
keywords: Hindfoot alignment; Knee osteoarthritis; Pre-operative severity; Total knee arthroplasty