title: Migration of cemented stem and restrictor after total hip arthroplasty: a radiostereometry study of 25 patients with Lubinus SP II stem.
abstract: The aim of this study was to investigate the migration pattern of the Lubinus SP II prosthesis stem. Migration at the stem-cement and at the bone-cement interface was assessed. Twenty-five patients were studied by radiostereometry during a period of 2 years. The migration of the head, of 2 points on the collar, of the stem tip, and also of the cement restrictor, was measured. The collar and the head were found stable at 2 years' follow-up, whereas an anterior migration occurred at the stem tip (median, 0.3 mm; 25th percentile, 0.04 mm; 75th percentile, 1.27 mm). Virtually no subsidence or axial rotation of the stems was observed. An anterior migration of the restrictor marker was also observed, compatible with a rigid sagittal plane rotation of the stem and of the cement mantle about the collar. Therefore, stem tip migration occurred at the bone-cement interface. Key words: total hip arthroplasty, anatomic stem, radiostereometry, subsidence, bone-cement interface.
authors.affiliation: Movement Analysis Laboratory, Istituti Ortopedici Rizzoli, Bologna, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Catani
authors.forename: Andrea
authors.initials: A
authors.lastname: Ensini
authors.forename: Alberto
authors.initials: A
authors.lastname: Leardini
authors.forename: Laura
authors.initials: L
authors.lastname: Bragonzoni
authors.forename: Soren
authors.initials: S
authors.lastname: Toksvig-Larsen
authors.forename: Sandro
authors.initials: S
authors.lastname: Giannini
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip; D005260:Female; D005500:Follow-Up Studies; D005548:Foreign-Body Migration; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications