title: Bone restoration with cemented Exeter universal stem - Three-years longitudinal DEXA study in 165 hips for femur.
abstract: BACKGROUND
  The pattern of strain distribution in the proximal femur changes following total hip arthroplasty (THA) and decreases in bone mineral density (BMD) occur around the stem following cemented and uncemented THA. We herein prospectively examined changes in BMD for 3 years after THA with a cemented Exeter universal stem.
  
  
  METHODS
  One hundred and sixty five hips from 150 patients who underwent unilateral THA were included as a cohort. Our patients included 20 men (20 hips) and 130 women (145 hips) with a mean age of 63.9 years. BMD was measured 2 weeks postoperatively (baseline) and 3, 6 12, 18, 24, 30, and 36 months (3 years) after surgery using dual-energy X-ray absorptiometry (DEXA) on the lumbar spine and proximal femur of the operated side according to the Gruen zone classification. We quantified longitudinal changes in BMD for more than 3 years after surgery and detected several factors which affected these changes.
  
  
  RESULTS
  In the first year, BMD in the most proximal femur showed a 5.5% reduction at the lateral side (zone 1) and 13% reduction at the medial side (zone 7), with no significant BMD reductions being observed thereafter. BMD reductions at 3 years were the most apparent at the proximal medial part of the femur (zone 7; -10.3%), while BMD ratio change in zone 1 was over the baseline (+2.9%). Especially in zone 7, the BMD ratio decreased with female, decreases in weight, decreases in height, decreases in BMI, and increases in age at the time of surgery.
  
  
  CONCLUSIONS
  Bone restoration is expected with a cemented Exeter universal stem. Male patients, a younger age, a high body weight, being tall, and a high BMI were identified as factors associated with the restoration of BMD in proximal femur.
authors.affiliation: Department of Orthopedic Surgery, Hamamatsu Medical Center, 328 Tomitsuka-cho, Naka-ku, Hamamatsu, Shizuoka 432-8580, Japan.
authors.forename: Daigo
authors.initials: D
authors.lastname: Morita
authors.affiliation: Department of Orthopedic Surgery, Hamamatsu Medical Center, 328 Tomitsuka-cho, Naka-ku, Hamamatsu, Shizuoka 432-8580, Japan. Electronic address: tossy.iwase@gmail.com.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Iwase
authors.affiliation: Department of Orthopedic Surgery, Hamamatsu Medical Center, 328 Tomitsuka-cho, Naka-ku, Hamamatsu, Shizuoka 432-8580, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Ito
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000367:Age Factors; D000704:Analysis of Variance; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000379:methods*; D001843:Bone Cements; D015519:Bone Density / Q000502:physiology; D016723:Bone Remodeling / Q000502:physiology*; D002484:Cementation / Q000379:methods; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006622:Hip Prosthesis; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000601:surgery*; D011182:Postoperative Care / Q000379:methods; D011446:Prospective Studies; D011474:Prosthesis Design; D018570:Risk Assessment; D012737:Sex Factors; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D001843:Bone Cements