title: Bone mineral density of the femoral neck is increased after successful lumbar spine surgery: a 2-year prospective analysis.
abstract: METHODS
  Prospective study.
  
  
  OBJECTIVE
  To determine whether or not lumbar spine surgery increases bone mineral density (BMD) of the vertebral body and/or the femoral neck, and if it is in fact related to an increase of postoperative BMD. This study was further designed to analyze the factors involved in the BMD increase.
  
  
  BACKGROUND
  Long-term immobilization results in bone loss. Inactive patients who are bedridden or restricted to wheelchair mobility may have a low BMD due to immobilization. Successful lumbar spine surgery improves the activities of daily living. Thus, it might lead to an increase in BMD of the body.
  
  
  METHODS
  Forty-seven Japanese patients, older than 60 years, who had lumbar spine surgery in the period from January to December 2009 were included. BMD of the vertebral body and the femoral neck was measured by dual-energy x-ray absorptiometry preoperatively and at 1 and 2 years after surgery, respectively. The surgical results and activities of daily living were evaluated by the Japanese Orthopaedic Association score. Walking ability was evaluated using the Nurick scale.
  
  
  RESULTS
  The average preoperative BMD of the lumbar spine and the femoral neck gradually decreased postoperatively. BMD of the femoral neck in the excellent group, according to the postoperative Nurick scale, had increased at the 2-year follow-up period. There were significant differences in the percent change of BMD of both the vertebral body and the femoral neck among the groups that was categorized by the postoperative Nurick scale grades.
  
  
  CONCLUSIONS
  Successful lumbar spine surgery might increase BMD of the femoral neck. The percent change of BMD of both the vertebral body and the femoral neck was related to postoperative walking ability.
  
  
  METHODS
  3.
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, University of Toyama, Toyama 930-0194, Toyama, Japan. zenji@med.u-toyama.ac.jp
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Kawaguchi
authors.forename: Masato
authors.initials: M
authors.lastname: Nakano
authors.forename: Taketoshi
authors.initials: T
authors.lastname: Yasuda
authors.forename: Shoji
authors.initials: S
authors.lastname: Seki
authors.forename: Takeshi
authors.initials: T
authors.lastname: Hori
authors.forename: Tomoatsu
authors.initials: T
authors.lastname: Kimura
mesh_terms: D015502:Absorptiometry, Photon; D000203:Activities of Daily Living; D015519:Bone Density; D005272:Femur Neck / Q000000981:diagnostic imaging / Q000378:metabolism*; D006801:Humans; D008159:Lumbar Vertebrae / Q000378:metabolism* / Q000601:surgery*; D011446:Prospective Studies; D013997:Time Factors; D016896:Treatment Outcome; D016138:Walking