Retrieval study of uncemented metal-metal hip prostheses revised for early loosening.
A tribologic assessment was performed on 22 metal-metal hip prostheses from a single manufacturer, following removal for early aseptic loosening after a mean service life of 32 months (range, 12-59 months). The mean linear wear rate was 7.6 microm/year (range, 2.9-12.8 microm/year). This was below the rates previously observed in other modern metal-metal combinations. A novel contour analysis technique using a coordinate measuring machine showed the mean volumetric wear rate to be 2.02 mm(3)/year (range, 0.55-3.74 mm(3)/year), which corresponds to a mean gravimetric wear rate of 16.9 mg/year (range, 4.6-31.4 mg/year). The mean clearance of 39.8 microm (range, 30-50 microm) was within the optimal range for hard-hard bearing combinations. Evidence of abrasive, adhesive, and third-body wear was found on all bearing surfaces. The tribologic assessment did not indicate manufacturing defects as a cause of early loosening. Equally, third-body wear was too low to be considered a causative factor for early loosening.
Reinisch
Georg
G
Department of Micro-Technique and Precision Engineering, Vienna University of Technology, Floragasse 7, A 1040 Vienna, Austria. reinisch@jic.at
Judmann
Kurt P
KP
Lhotka
Christian
C
Lintner
Felix
F
Zweymüller
Karl A
KA
D000497:Alloys; D019644:Arthroplasty, Replacement, Hip; D001843:Bone Cements; D005269:Femur; D006622:Hip Prosthesis; D006801:Humans; D008670:Metals; D008855:Microscopy, Electron, Scanning; D011475:Prosthesis Failure; D013997:Time Factors; D014961:X-Ray Diffraction
D000497:Alloys; D001843:Bone Cements; D008670:Metals