title: Fixation and bone remodeling around a low-modulus stem seven-year follow-up of a randomized study with use of radiostereometry and dual-energy x-ray absorptiometer.
abstract: Thirty-eight patients (40 hips) randomly received either an uncemented fully porous-coated composite stem (Epoch; Zimmer, Warsaw, Ind) or an uncemented proximally porous-coated solid stem (Anatomic; Zimmer). Patients were followed up for 7 years using radiostereometry, dual-energy x-ray absorptiometry, conventional radiography, the Harris Hip Score, and a pain questionnaire. Both stem designs achieved excellent outcome for fixation (stem subsidence and stem rotations close to zero) and clinical outcome, without any difference between the 2 groups (P > .12). Median wear rates were low despite use of conventionally gamma-sterilized polyethylene. No stem was radiographically loose on the postoperative radiographs. The low-modulus composite stem had positive effects on early proximal bone remodeling in Gruen regions 1, 2, 6, and 7 (P < .04). However, at 7 years, this bone-sparing effect persisted in only the calcar region (Gruen region 7).
authors.affiliation: Departments of Orthopaedics, Sahlgrenska University Hospital, University of Gothenburg, Sweden.
authors.forename: Truike M
authors.initials: TM
authors.lastname: Thien
authors.forename: Jonas
authors.initials: J
authors.lastname: Thanner
authors.forename: Johan
authors.initials: J
authors.lastname: Kärrholm
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D016723:Bone Remodeling; D005260:Female; D005500:Follow-Up Studies; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011474:Prosthesis Design; D060489:Prosthesis Retention; D059869:Radiostereometric Analysis; D013997:Time Factors