title: The effect of long-term alendronate treatment on cortical thickness of the proximal femur.
abstract: BACKGROUND
  One of the radiographic hallmarks in patients with atypical femoral insufficiency fractures after prolonged bisphosphonate treatment is generalized cortical hypertrophy. Whether cortical thickening in the proximal femur is caused by long-term alendronate therapy, however, remains unknown.
  
  
  OBJECTIVE
  We asked whether long-term alendronate use of 5 years or more results in progressive thickening of the subtrochanteric femoral cortices.
  
  
  METHODS
  We retrospectively evaluated changes in cortical thickness and cortical thickness ratio (ratio of cortical to femoral shaft diameter) at the subtrochanteric region of the proximal femur in baseline and latest hip dual-energy xray absorptiometry (DXA) scans of 131 patients. The mean followup was 7.3 years. Patients were divided into two groups: control (no history of alendronate, 45 patients) and alendronate (history of alendronate ≥ 5 years, 86 patients). We determined cortical thickness and cortical thickness ratio at 3.5 and 4.0 cm below the tip of the greater trochanter, representing the subtrochanteric region.
  
  
  RESULTS
  After a minimum of 5 years followup, mean cortical thickness decreased approximately 3% in the alendronate and control groups. The cortical thickness at the subtrochanteric femoral region changed less than 1 mm in greater than 90% of the patients with long-term alendronate treatment. We observed no differences in mean changes of cortical thickness and percent changes of cortical thickness between the two groups.
  
  
  CONCLUSIONS
  Long-term alendronate treatment did not appear to cause thickened femoral cortices within the detection limits of our method. This finding contrasts with the notion that long-term alendronate treatment leads to generalized cortical thickening.
authors.affiliation: Department of Orthopaedic Surgery, Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021, USA. uaasis@gmail.com
authors.forename: Aasis
authors.initials: A
authors.lastname: Unnanuntana
authors.forename: Kashif
authors.initials: K
authors.lastname: Ashfaq
authors.forename: Quang V
authors.initials: QV
authors.lastname: Ton
authors.forename: John P
authors.initials: JP
authors.lastname: Kleimeyer
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Lane
mesh_terms: D000368:Aged; D019386:Alendronate / Q000008:administration & dosage*; D015519:Bone Density / Q000187:drug effects; D050071:Bone Density Conservation Agents / Q000008:administration & dosage*; D016022:Case-Control Studies; D003720:Densitometry / Q000379:methods; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D005264:Femoral Fractures / Q000000981:diagnostic imaging / Q000453:epidemiology; D005269:Femur / Q000000981:diagnostic imaging / Q000187:drug effects*; D005500:Follow-Up Studies; D005598:Fractures, Spontaneous / Q000000981:diagnostic imaging / Q000453:epidemiology; D006801:Humans; D008134:Long-Term Care; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000517:prevention & control; D011859:Radiography; D012016:Reference Values; D012720:Severity of Illness Index; D013997:Time Factors; D017211:Treatment Failure
chemical_list: D050071:Bone Density Conservation Agents; D019386:Alendronate