title: In vivo measurement of volumetric wear of a total knee replacement.
abstract: A new Roentgen Stereophotogrammetric Analysis (RSA) system is reported; it can measure penetration of the metallic femoral component of a Total Knee Replacement (TKR) prosthesis into the polyethylene bearing on the tibial component. This system was used to analyse a study group of six Anatomic Graduated Components (AGC) knee prostheses more than 6 years post-implantation, and to compare with a control group of six newly implanted AGC prostheses. The volumetric loss of polyethylene was estimated by imaging each prosthesis at a series of different knee flexion angles. The mean difference between the RSA measured polyethylene bearing thickness and the manufacturer's quoted values for the control group was -0.03 mm (SD 0.17). The estimated linear penetration at 6.4 years in this prosthesis was determined to be 0.1 mm/year. Volumetric wear was estimated to be 600-700 mm(3)/year at 6.4 years, equating to approximately 100 mm(3)/year. This does not appear to be clinically significant amount of wear as this prosthesis has excellent survival at 10 years.
authors.affiliation: OOEC/Nuffield Department of Orthopaedic Surgery, University of Oxford, Nuffield Orthopaedic Centre, Oxford, OX3 7LD, UK. richie.gill@ndos.ox.ac.uk
authors.forename: H S
authors.initials: HS
authors.lastname: Gill
authors.forename: J C
authors.initials: JC
authors.lastname: Waite
authors.forename: A
authors.initials: A
authors.lastname: Short
authors.forename: C F
authors.initials: CF
authors.lastname: Kellett
authors.forename: A J
authors.initials: AJ
authors.lastname: Price
authors.forename: D W
authors.initials: DW
authors.lastname: Murray
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee; D016022:Case-Control Studies; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000601:surgery; D007720:Knee Prosthesis; D008422:Materials Testing; D008875:Middle Aged; D010780:Photogrammetry / Q000379:methods; D020959:Polyethylene; D011856:Radiographic Image Enhancement / Q000379:methods; D016474:Weight-Bearing
chemical_list: D020959:Polyethylene