title: Adaptive Bone Remodeling of the Femoral Bone After Tumor Resection Arthroplasty With an Uncemented Proximally Hydroxyapatite-Coated Stem.
abstract: Loss of bone stock and stress shielding is a significant challenge in limb salvage surgery. This study investigates the adaptive bone remodeling of the femoral bone after implantation of a tumor prosthesis with an uncemented press fit stem. We performed a prospective 1 yr follow-up of 6 patients (mean age: 55 (26-78) yr, female/male=3/3) who underwent bone tumor resection surgery of the proximal femur (n=3) or distal femur (n=3). Reconstruction was done using a Global Modular Replacement System (Stryker® Orthopaedics, Mahwah, NJ) tumor prosthesis, and all patients received a straight-fluted 125-mm uncemented press-fit titanium alloy stem with hydroxyapatite coating of the proximal part of the stem. Measurements of bone mineral density (BMD; g/cm2) were done postoperatively and after 3, 6, and 12 mo in the part of the femur bone containing the Global Modular Replacement System stem using dual-energy X-ray absorptiometry. BMD was measured in 3 regions of interest (ROIs) in the femur bone. Nonparametric analysis of variance (Friedman test) for evaluation of changes in BMD over time. BMD decreased in all 3 ROIs with time. In ROI 1 (p=0.01), BMD decreased by 10% after 3 mo and ended with a total decrease of 14% after 1 yr. In ROI 2 (p=0.006), BMD was decreased by 6% after 3 and 6 mo; after 1 yr of follow-up, BMD was 9% below the postoperative value. In ROI 3 (p=0.009), BMD decreased by 6% after 3 and 6 mo; after 1 yr of follow-up, BMD was 8% below the postoperative value. A bone loss of 8%-9% during the first postoperative year was seen along the femoral stem, but in the bone containing the hydroxyapatite-coated part of the stem, the decrease in BMD was 14%, thus indicating that stress shielding of this part of the bone may play a role for the adaptive bone remodeling.
authors.affiliation: Department of Orthopedic Surgery, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark. Electronic address: mikkelra1@hotmail.com.
authors.forename: Mikkel R
authors.initials: MR
authors.lastname: Andersen
authors.affiliation: Department of Orthopedic Surgery, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Petersen
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods; D001672:Biocompatible Materials / Q000494:pharmacology; D015519:Bone Density; D001859:Bone Neoplasms / Q000473:pathology / Q000601:surgery; D016723:Bone Remodeling; D003718:Denmark; D017886:Durapatite / Q000494:pharmacology*; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000601:surgery; D005500:Follow-Up Studies; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control; D011183:Postoperative Complications / Q000175:diagnosis / Q000517:prevention & control; D011474:Prosthesis Design; D012512:Sarcoma, Ewing / Q000473:pathology / Q000601:surgery
chemical_list: D001672:Biocompatible Materials; D017886:Durapatite
keywords: BMD; DXA; bone remodeling; limb salvage; tumor prosthesis