title: Progression of osteoarthritis of the knee after unilateral total hip arthroplasty: minimum 10-year follow-up study.
abstract: BACKGROUND
  Patients undergoing total hip arthroplasty (THA) exhibit changes in the alignment of lower extremities following the procedure, and these changes may exert effects on other joints over the long-term. Therefore, we investigated the course of knee osteoarthritis in patients undergoing long-term follow up after THA, in addition to the relationship between the course of knee osteoarthritis and alignment of lower extremities.
  
  
  METHODS
  We retrospectively performed radiographic evaluation of the course of knee osteoarthritis (OA) after THA. Thirty patients undergoing successful unilateral THA were followed for a minimum of 10 years.
  
  
  RESULTS
  Eleven (33%) subjects showed progression of medial tibiofemoral OA on the non-THA side, while only three (10%) showed progression on the THA side, and this difference was significant (P = 0.033). In addition, the mechanical axes on the THA side passed through more lateral regions of the tibial plateau than those on the non-THA side (P = 0.044).
  
  
  CONCLUSIONS
  Medial tibiofemoral OA on the THA side was less likely to deteriorate than on the non-THA side. The reduced vulnerability to OA progression on the THA side may be due to the lower offset and resultant lateral shift in mechanical axes.
authors.affiliation: Department of Orthopaedic Surgery, Kansai Rosai Hospital, 3-1-69, Inabaso, Amagasaki City, Hyogo 660-8511, Japan. umedazz@jc4.so-net.ne.jp
authors.forename: Naoya
authors.initials: N
authors.lastname: Umeda
authors.forename: Hidenobu
authors.initials: H
authors.lastname: Miki
authors.forename: Takashi
authors.initials: T
authors.lastname: Nishii
authors.forename: Hideki
authors.initials: H
authors.lastname: Yoshikawa
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Sugano
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000209:etiology; D011859:Radiography; D012189:Retrospective Studies