A Morphological Analysis of Metal Transfer Surface Damage to Ceramic & Cobalt Chrome Femoral Heads
Thursday, May 18, 2017
2:00 PM-4:00 PM
BIOMED Master's Thesis Defense
Title:
A Morphological Analysis of Metal Transfer Surface Damage to Ceramic and Cobalt Chrome Femoral Heads: A Retrieval Study
Speaker:
Eliza Fredette, MS Candidate, School of Biomedical Engineering, Science and Health Systems
Advisor:
Steven Kurtz, PhD, Associate Research Professor, School of Biomedical Engineering, Science and Health Systems
Abstract:
Metal transfer has been observed on retrieved femoral heads in total hip replacements. In vitro wear testing has shown increased wear of the polyethylene acetabular liner with the presence of metal transfer on femoral heads. Although metal transfer has been observed, there is little known about the effects that bearing surface materials may have on the morphology of metal transfer. This study sought to investigate the extent of metal transfer on the bearing surface of CoCr and ceramic femoral heads, and to identify prevalent patterns and morphologies.
Three bearing couple cohorts: M-PE (n=50), C-PE (n=35), and C-C (n=15), were derived from two previously matched collections (n=50/group) of CoCr and ceramic femoral heads. The three cohorts in the present study were semi-quantitatively assessed for the presence of metal transfer. The morphology of femoral heads with visual evidence of metal transfer (score ≥ 2) was analyzed using direct measurement, digital photogrammetry, and white light interferometry. Metal transfer was observed on 75% (n=75/100) of the femoral heads. Surface area coverage and curved median surface area were similar among the three cohorts (Median Coverage 2.3% (IQR: 4.1%), p =0.90; Median Surface Area = 39.8 mm (IQR: 67.5 mm), p = 0.977). The most prevalent metal transfer patterns observed were random stripes (n = 21/75), longitudinal stripes (n = 17/75), and random patches (n = 13/75). The arc length was shorter in the M-PE cohort (mean difference C-PE = 5.7 mm, C-C = 7.11 mm; p <0.001). The height of the metal transfer was greater for the M-PE cohort (mean difference C-PE= 0.77 μm, C-C = 0.84 μm, p = 0.014).
Understanding the morphology of metal transfer may be useful for more accurate polyethylene wear studies through more realistic re-creation of metal transfer in in-vitro pin-on-disk and joint simulators studies.
Contact Information
Ken Barbee
215-895-1335
barbee@drexel.edu