title: Hip revision with impacted morselized allografts: unrestricted weight-bearing and restricted weight-bearing have similar effect on migration. A radiostereometry analysis.
abstract: BACKGROUND
  No consensus exists as to whether to let patients bear weight or not after revision of a loosened hip prosthesis using morselized and impacted allograft bone and cement. In the original description of the method, the patients were advised not to bear weight for 3 months postoperatively. Theoretically, bone graft remodeling is enhanced by mechanical load, but an increased migration of the prosthesis within the graft can also be anticipated. In addition, practicing restricted weight-bearing is cumbersome for the patients.
  
  
  METHODS
  The present study was initiated to evaluate the migration, as measured by radiostereometry analysis (RSA), in patients mobilized with unrestricted weight-bearing after a hip revision using the X-change Revision Instruments System. This group was compared with a previous series with restricted weight-bearing for the initial 3 months postoperatively. Seven stems and 12 sockets were evaluated by RSA over 2 years. Only patients without intraoperative complications were mobilized with unrestricted weight-bearing.
  
  
  RESULTS
  All 7 stems migrated in the distal direction (median 2.6 mm; range 0.8-16.5 mm) and in the posterior direction (median 2.3 mm; range 0.7-22.1 mm). Eleven of the 12 sockets migrated in the proximal direction (median 2.5 mm; range 0.2-8.1 mm). The migration rate decreased gradually in all directions, but 3 stems and 5 sockets still migrated between the 1.5- and 2-year follow-ups. There were no significant differences in migration in any direction for either the stems or the sockets compared to the group with restricted weight-bearing.
  
  
  CONCLUSIONS
  No increased migration occurred in the group free to bear weight as compared to restricted weight-bearing. We shall continue to allow unrestricted weight-bearing in cases where the femoral bone feels competent to withstand the initial load. It simplifies the postoperative mobilization, and we speculate that it might increase the remodeling of the graft.
authors.affiliation: Department of Orthopedics, Hässleholm-Kristianstad County Hospital, Sweden. ewald.ornstein@skane.se
authors.forename: Ewald
authors.initials: E
authors.lastname: Ornstein
authors.forename: Herbert
authors.initials: H
authors.lastname: Franzén
authors.forename: Ragnar
authors.initials: R
authors.lastname: Johnsson
authors.forename: Anna
authors.initials: A
authors.lastname: Stefánsdóttir
authors.forename: Martin
authors.initials: M
authors.lastname: Sundberg
authors.forename: Magnus
authors.initials: M
authors.lastname: Tägil
mesh_terms: D019644:Arthroplasty, Replacement, Hip; D016723:Bone Remodeling / Q000502:physiology; D016025:Bone Transplantation / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006621:Hip Joint / Q000601:surgery*; D006801:Humans; D008297:Male; D010780:Photogrammetry; D011475:Prosthesis Failure; D014184:Transplantation, Homologous; D016896:Treatment Outcome; D016474:Weight-Bearing / Q000502:physiology*