title: Pelvic periprosthetic bone mineral density measurement around cemented vs cementless acetabular prostheses.
abstract: We compared the short-term precision of pelvic periprosthetic bone mineral density (BMD) measurement around a cementless acetabular prosthesis (n = 29) vs a cemented all-polyethylene acetabular prosthesis (n = 19) in patients after total hip arthroplasty. Two dual-energy x-ray absorptiometry scans of the pelvis were made on the same day in each subject with subject repositioning between scans and analyzed independently with a 4-region of interest model. Precision was expressed as coefficient of variation (CV%). The measured BMD around the cemented prostheses was greater than the cementless prostheses p < 0.004, all analyses). The net CV for pelvic BMD measurements around the cementless prosthesis was 1.9% vs 3.6% around the cemented prosthesis (F-test p < 0.001). The CVs of individual regions of interest was between 2.8% and 4.8% for the cementless prosthesis vs 4.4% to 8.4% for the cemented prosthesis (F-test; p < 0.05, all comparisons). Prospective studies would require 57 subjects to detect a 10% change in net pelvic BMD around a cementless prosthesis and 122 to detect a similar change around a cemented prosthesis with 90% power and with an alpha error of 0.05. In conclusion, the precision of pelvic BMD measurements made around cementless prostheses are better vs those for cemented prostheses. Dual-energy x-ray absorptiometry studies of cemented prosthesis require approximately double the number of subjects vs cementless prostheses to achieve a similar level of power.
authors.affiliation: Academic Unit of Bone Metabolism, Department of Human Metabolism, University of Sheffield, Sheffield, United Kingdom.
authors.forename: Raveen L
authors.initials: RL
authors.lastname: Jayasuriya
authors.affiliation: Academic Unit of Bone Metabolism, Department of Human Metabolism, University of Sheffield, Sheffield, United Kingdom. Electronic address: j.m.wilkinson@sheffield.ac.uk.
authors.forename: J Mark
authors.initials: JM
authors.lastname: Wilkinson
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D001843:Bone Cements; D015519:Bone Density; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging* / Q000601:surgery; D010384:Pelvic Bones / Q000000981:diagnostic imaging*; D011446:Prospective Studies; D011474:Prosthesis Design; D015203:Reproducibility of Results
chemical_list: D001843:Bone Cements
keywords: BMD; DXA; pelvis; precision; total hip arthroplasty