title: Bone remodelling after femoral short stem implantation in total hip arthroplasty: 1-year results from a randomized DEXA study.
abstract: BACKGROUND
  Short stem prostheses have been developed to preserve proximal femoral bone stock. This prospective, randomized study compared periprosthetic bone remodelling following short and straight stem implantation 1 year after surgery.
  
  
  METHODS
  One hundred and forty-four consecutive patients undergoing total hip arthroplasty were randomized to either a Fitmore short or a cementless straight stem (both Zimmer, Winterthur, Switzerland). Periprosthetic bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry performed the day before surgery and at 7 days, 3 months and 1 year postoperatively. Furthermore, the HHS and the WOMAC were obtained.
  
  
  RESULTS
  One hundred and thirty-eight patients completed 1-year follow-up. Periprosthetic BMD changes at 1 year were most pronounced in the proximal medial region of interest (ROI) 7 with -17.2% after short stem and -16.7% after straight implantation (p = 0.67). However, there was significantly less BMD reduction in ROI 6 following short (-4.7%) versus straight stem (-10.8%) implantation (p = 0.01). There were no significant differences between the two groups in terms of the HHS and the WOMAC either before or after surgery.
  
  
  CONCLUSIONS
  One year after surgery, both stems showed an implant-specific periprosthetic bone remodelling. Nevertheless, proximal load transfer was more pronounced after short stem implantation than with a straight stem.
authors.affiliation: Department of Orthopaedic Surgery, University of Ulm, Oberer Eselsberg 45, 89081, Ulm, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Freitag
authors.affiliation: Department of Orthopaedic Surgery, University of Ulm, Oberer Eselsberg 45, 89081, Ulm, Germany.
authors.forename: Marie-Anne
authors.initials: MA
authors.lastname: Hein
authors.affiliation: Department of Orthopaedic Surgery, University of Ulm, Oberer Eselsberg 45, 89081, Ulm, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Wernerus
authors.affiliation: Department of Orthopaedic Surgery, University of Ulm, Oberer Eselsberg 45, 89081, Ulm, Germany.
authors.forename: Heiko
authors.initials: H
authors.lastname: Reichel
authors.affiliation: Department of Orthopaedic Surgery, University of Ulm, Oberer Eselsberg 45, 89081, Ulm, Germany. ralf.bieger@uni-ulm.de.
authors.forename: Ralf
authors.initials: R
authors.lastname: Bieger
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation* / Q000379:methods; D015519:Bone Density; D016723:Bone Remodeling; D005260:Female; D005500:Follow-Up Studies; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D011184:Postoperative Period; D011446:Prospective Studies; D016896:Treatment Outcome; D055815:Young Adult
keywords: Arthroplasty; DEXA; Hip; Prosthesis design; Short stem; Stress shielding