title: Periprosthetic bone mineral density and fixation of the uncemented CLS stem related to different weight bearing regimes: A randomized study using DXA and RSA in 38 patients followed for 5 years.
abstract: OBJECTIVE
  There is no consensus on the best rehabilitation regime after uncemented total hip arthroplasty. Theoretically, bone ingrowth into the implant should benefit from initial partial weight bearing. We investigated whether the degree of postoperative weight bearing influences the periprosthetic bone mineral density (BMD) and/or the stability of the CLS stem.
  
  
  METHODS
  38 patients received an uncemented CLS stem and were randomized to either unrestricted postoperative weight bearing or to partial weight bearing for 3 months. Periprosthetic BMD was measured in the 7 Gruen zones with DXA and the stability of the femoral stem was assessed by radiostereometric analysis (RSA) after surgery and at 3, 12, 24, and 60 months.
  
  
  RESULTS
  Periprosthetic BMD was not influenced by the type of postoperative weight bearing. BMD was reduced by 8-15% in all Gruen zones at 3 months. Restoration toward initial BMD was observed in all zones except in zone 7 (calcar region), where BMD was reduced by 22% at 5 years. Immediate weight bearing after surgery had no influence on the stability of the CLS stem, as assessed by RSA.
  
  
  CONCLUSIONS
  Immediate full weight bearing after uncemented total hip arthroplasty is safe. There is no difference in the periprosthetic BMD or in stability of the stem as measured by RSA compared to partial weight bearing for 3 months. BMD is reduced by more than 20% in the calcar region around a CLS stem after 5 years.
authors.affiliation: Department of Orthopedics, Uppsala University Hospital, Uppsala, Sweden. olof.wolf@akademiska.se
authors.forename: Olof
authors.initials: O
authors.lastname: Wolf
authors.forename: Per
authors.initials: P
authors.lastname: Mattsson
authors.forename: Jan
authors.initials: J
authors.lastname: Milbrink
authors.forename: Sune
authors.initials: S
authors.lastname: Larsson
authors.forename: Hans
authors.initials: H
authors.lastname: Mallmin
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000379:methods / Q000534:rehabilitation; D015519:Bone Density; D002484:Cementation; D005260:Female; D005500:Follow-Up Studies; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery; D010780:Photogrammetry; D013997:Time Factors; D016474:Weight-Bearing
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