Influence of third-body particles originating from bone void fillers on the wear of ultra-high-molecular-weight polyethylene

Abstract

Calcium sulfate bone void fillers are increasingly being used for dead space management in infected arthroplasty revision surgery. The presence of these materials as loose beads close to the bearing surfaces of joint replacements gives the potential for them to enter the joint becoming trapped between the articulating surfaces; the resulting damage to cobalt chrome counterfaces and the subsequent wear of ultra-high-molecular-weight polyethylene is unknown. In this study, third-body damage to cobalt chrome counterfaces was simulated using particles of the calcium sulfate bone void fillers Stimulan® (Biocomposites Ltd., Keele, UK) and Osteoset® (Wright Medical Technology, TN, USA) using a bespoke rig. Scratches on the cobalt chrome plates were quantified in terms of their density and mean lip height, and the damage caused by the bone void fillers was compared to that caused by particles of SmartSet GMV PMMA bone cement (DePuy Synthes, IN, USA). The surface damage from Stimulan® was below the resolution of the analysis technique used; SmartSet GMV caused 0.19 scratches/mm with a mean lip height of 0.03 µm; Osteoset® led to a significantly higher number (1.62 scratches/mm) of scratches with a higher mean lip height (0.04 µm). Wear tests of ultra-high-molecular-weight polyethylene were carried out in a six-station multi-axial pin on plate reciprocating rig against the damaged plates and compared to negative (highly polished) and positive control plates damaged with a diamond stylus (2 µm lip height). The wear of ultra-high-molecular-weight polyethylene was shown to be similar against the negative control plates and those damaged with third-body particles; there was a significantly higher (p < 0.001) rate of ultra-high-molecular-weight polyethylene wear against the positive control plates. This study showed that bone void fillers of similar composition can cause varying damage to cobalt chrome counterfaces. However, the lip heights of the scratches were not of sufficient magnitude to increase the wear of ultra-high-molecular-weight polyethylene above that of the negative controls.

Antibiotic loaded calcium sulfate bead and pulse lavage eradicates biofilms on metal implant materials in vitro

“…A clinical concern with using resorbable mineral beads to treat PJI is third body wear of articulating surfaces. While we did find one report of third body wear in six patients associated with hydroxy apatite acetabular cup coating, in vitro tribological and hip simulator testing suggest that calcium sulfate has the potential to be used as an antibiotic carrier, without resulting in excessive third body wear . Another concern associated with localized antibiotic therapy is that of the development of antibiotic resistance if the infecting bacteria are exposed to sub‐MIC concentrations for prolonged periods.…”

The influence of a calcium sulphate bone void filler on the third-body damage and polyethylene wear of total knee arthroplasty

“…Medical-grade calcium sulphate, for example, is derived from earth-sourced gypsum rock and is a relatively soft material with a value of 2 on the Mohs scale. 36 However, it may contain insoluble and potentially harder impurities such as quartz (7 on the Mohs scale) 36 or slower-absorbing calcium phosphate constituents that may have an influence on the wear of UHMWPE, 21 meaning that the findings from this study do not translate directly to all bone void filler materials.…”

“…19 The influence of calcium sulphate on third-body wear has been previously investigated in the hip 20 and in simple geometry pin-on-plate/pin-on-disc studies. 21,22 In all studies, calcium sulphate did not scratch the surface of CoCr counterfaces with a lip height of sufficient magnitude to influence polyethylene wear rate. The hip simulation study, however, showed an elevated wear rate while calcium sulphate was present in the lubricant.…”

“…The hip simulation study, however, showed an elevated wear rate while calcium sulphate was present in the lubricant. 20 The pin-on-plate study by Cowie et al 21 compared calcium sulphate products of similar composition differing by the processing route of the base material and therefore their purity. Hard earth impurities in one of the calcium sulphates tested were thought to contribute to scratching of CoCr counterfaces, although the lip height of the scratches was not of sufficient magnitude to influence polyethylene wear.…”

“…However, these tests were carried out in a simple geometric configuration and over a relatively short duration. 21…”