title: A prospective randomized radiographic and dual-energy X-ray absorptiometric study of migration and bone remodeling after implantation of two modern short-stemmed femoral prostheses.
abstract: BACKGROUND
  The aim of this prospective randomized study was to analyze migration and strain transmission of the Metha™ and Nanos™ femoral prostheses.
  
  
  METHODS
  Between 1 January 2011 and 2 April 2013, 50 patients were randomized to receive short-stemmed femoral prostheses. Metha™ stems were implanted in 24 patients (12 female, 12 male; mean age 58.7 years; mean body mass index [BMI] 27.4) and Nanos™ stems in 26 patients (10 female, 16 male; mean age 59.7 years; mean BMI 27.1). Longitudinal stem migration, varus-valgus alignment, changes of center of rotation (COR), femoral offset and caput-collum-diaphyseal angle, leg length discrepancy, periprosthetic radiolucent lines incidence, and dual-energy X-ray absorptiometry (DEXA) scans were analysed after an average of 98 and 381 days.
  
  
  RESULTS
  There was no significant change of varus-valgus alignment or clinically relevant migration of the Metha™ or Nanos™ prostheses during postoperative follow-up. After 12.3 months, the DEXA scans showed small but significant differences of bone mineral density in Gruen zones 1 (minus ~8 %) and 6 (plus ~9 %) for the Metha™ and in Gruen zone 1 (minus ~14 %) for the Nanos™ (paired t test). Visual analog scale (VAS) and Harris Hip Score (HHS) improved significantly for both implants (Nanos™/Metha™ 12.3 months postoperatively HSS 96.5/96.2; VAS 0.7/0.8, respectively). COR or offset did not change significantly after surgery.
  
  
  CONCLUSIONS
  Neither implant showed signs of impaired osseointegration. DEXA demonstrated proximally located load transfer with only moderate proximal stress shielding.
  
  
  METHODS
  II.
authors: Department of Orthopaedics and Traumatology, Faculty of Medicine, Martin-Luther-University of Halle-Wittenberg, Ernst-Grube-Strasse 40, 06120, Halle/Saale, Germany.
authors: Volker
authors: V
authors: Brinkmann
authors: Florian
authors: F
authors: Radetzki
authors: Karl Stefan
authors: KS
authors: Delank
authors: David
authors: D
authors: Wohlrab
authors: Alexander
authors: A
authors: Zeh
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D015519:Bone Density; D016723:Bone Remodeling; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging* / Q000601:surgery*; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure