Ceramic femoral heads prevent runaway wear for highly crosslinked polyethylene acetabular cups by third-body bone cement particles

Aggressive 3rd-body wear challenge to highly crosslinked polyethylene: A hip simulator model

“…the CoCr was unaffected. The actual 'roughening' mechanism appeared to be the transient transfer layers of PMMA onto the counterfaces and the accelerated wear came from 2-body abrasion between PMMA and CXPE surfaces [17,18]. Our duplication of the PMMA studies by Dr. Wang supported these conclusions and while different types of PMMA debris were used, there was agreement that the PMMA did not adversely affect CoCr roughness [29].…”

“…Our phase-1 wear study showed virtually identical wear rates as the CXPE [32M] combination in previous work [29], but with much less of wear increase evident in phase-2. The previous simulator study [19] had shown that the wear magnitude of CXPE was directly related to the PMMA slurry concentration [18]. Thus, a decrease from 10 to 5 mg/ml PMMA would be expected to decrease the CXPE wear by 40% [18].…”

“…In phase II, the cups were run in PMMA slurry of 5 mg/ml in diluted bovine serum for 2.0 Mc [17]. A commercial polymethyl-methacrylate cement powder (Biomet Inc., Warsaw, IN, USA) was used as the "abrasive" medium [18,29].…”

“…Thus it is universally accepted that wear will be exacerbated by increased surface roughness of the CoCr counterfaces [3,11,[15][16][17][18][19][20][21][22]24,28]. 3rd-Body particles may include CoCr, Ti64, bone cement (PMMA) and hydroxyapatite, all used as implant coatings to facilitate biological attachment in various implant designs [25,31].…”

“…Since the size of particulates in the commercial PMMA powder (40 m) averaged 4-fold smaller than in Wang's study (150 m), the 2nd hypothesis was that wear magnitudes would be reduced by at least 50% relative to Dr. Wang's data. Based on previous observations that the metal counterfaces would be immune to PMMA roughening effects [18,29], the 3rd hypothesis was that there would be no change in roughness indices for CoCr bearings. Also based on observations that the alumina ball appeared immune to the PMMA transfer effects [17], the 4th hypothesis was that there would be no accelerated polyethylene wear of bearings when a ceramic counterface was involved.…”