title: Maintenance of proximal bone mass with an uncemented femoral stem analysis with dual-energy x-ray absorptiometry.
abstract: Bone ingrowth into uncemented femoral implants with proximal porous coatings has been designed to avoid proximal stress shielding and preserve femoral strength. Dual-energy x-ray absorptiometry allows repeated quantitative analysis of anteroposterior scans of the proximal femur. By use of dual-energy x-ray absorptiometry and qualitative radiographic changes, 31 total hip arthroplasties with an individually designed, proximally porous-coated prosthesis were evaluated after surgery and at intervals up to 2 years. All implants appeared to achieve successful bone ingrowth and subsequent remodeling. At the most proximal level around the neck osteotomy, the postoperative loss of bone density at 6 months was -14.5%, which persisted at 24 months with -11.6%. At the level of the distal portion of the porous coating in the lower metaphysis, the density change was -8.7%, but bone had remodeled at 24 months with a change in density of only -1.0% compared with the immediate postoperative scan. With a design that results in reliable proximal ingrowth, this study predicts that after an initial decline in bone density, a positive bone remodeling response occurs that could lead to long-term stable fixation of the femoral implant.
authors.affiliation: Department of Orthopaedic Surgery, Northwestern University Medical School, Chicago, Illinois, USA.
authors.forename: R L
authors.initials: RL
authors.lastname: Wixson
authors.forename: S D
authors.initials: SD
authors.lastname: Stulberg
authors.forename: G J
authors.initials: GJ
authors.lastname: Van Flandern
authors.forename: L
authors.initials: L
authors.lastname: Puri
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods*; D001843:Bone Cements; D015519:Bone Density; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000502:physiology*; D005500:Follow-Up Studies; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D008961:Models, Structural; D015203:Reproducibility of Results
chemical_list: D001843:Bone Cements