Mid-term migration of a cemented total hip replacement assessed by radiostereometric analysis.
We have previously reported the short-term migration of cemented Hinek femoral components using radiostereometric analysis (RSA). We now report the mid-term migration. During the first 2 years after implantation the prosthesis subsided into varus and rotated internally. Between years 3 and 8 the prosthesis continued to rotate internally with the head moving posteriorly (0.07 mm/year, P=0.004). It also continued to fall into varus with the tip moving laterally (0.07 mm/year, P=0.04). The head (0.06 mm/year, P<0.0001), shoulder (0.04 mm/year, P=0.0001) and tip (0.04 mm/year, P=0.001) continued to migrate distally. There were two cases of failure due to aseptic loosening during the follow-up period. During the second year both of these had posterior head migration, which was abnormally rapid (>2 SD from the mean). We have demonstrated that a cemented implant has slow but significant levels of migration and rotation for at least 8 years after implantation. Our study confirms that implants with abnormally rapid posterior head migration during the second year are likely to fail.
Alfaro-Adrian
J
J
Oxford Orthopaedic Engineering Centre, Nuffield Orthopaedic Centre, University of Oxford, Oxford, UK.
Gill
H S
HS
Marks
B E
BE
Murray
D W
DW
D001843:Bone Cements; D005069:Evaluation Studies as Topic; D005260:Female; D005500:Follow-Up Studies; D005548:Foreign-Body Migration / Q000000981:diagnostic imaging*; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D009068:Movement; D010780:Photogrammetry; D011379:Prognosis; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography
D001843:Bone Cements