Wear Performance of Calcium Carbonate-Containing Knee Spacers

Abstract

Articulating spacers should be wear-resistant and load-bearing to avoid prolonged immobilization of the patient and to reduce morbidity. However, due to the articulation of both components, a release of cement wear particles is to be expected. The aim of this study was to investigate the wear performance of a new spacer cement that contains calcium carbonate as a radio-opaque substance, in comparison to an established barium sulphate-containing spacer material, and also to characterize the amount, morphology, and size distributions of the released cement particles in detail. Force-controlled simulation was carried out on an AMTI knee simulator. The test parameters were in accordance with the standard ISO 14243-1 with a 50% reduced axial force. Tests were run for 500,000 cycles at a frequency of 1 Hz. For wear analysis, photographic documentation of the wear scars, gravimetric wear measurements and wear particle analysis were performed. The barium sulphate spacer material showed a total articular wear of 375.53 ± 161.22 mg. For the calcium carbonate-containing cement, reduced articular wear of 136.32 ± 37.58 mg was determined. Isolated cement wear particles of the barium sulphate-containing cement had a diameter of 0.429 ± 0.224 μm and were significantly larger compared to the calcium carbonate-containing cement (0.380 ± 0.216 μm, p = 0.02). The calcium carbonate-containing cement showed better wear performance in terms of gravimetric wear and particle release. Thus, calcium carbonate seems to be a promising material as a radio-opaque substrate in cement spacers.

Polyethylene-Based Knee Spacer for Infection Control: Design Concept and Pre-Clinical In Vitro Validations

“…The silicone mold material is soft and deformation of the cement during polymerization may occur (cement volume will expand but the mold was not strong enough to resist the expansion, so an irregular cement surface was then produced as shown in Figure 4 ). The wear test revealed acceptable results when comparing with the reported data in previous publication [ 24 ], even though the surface condition of the cement region was not ideal. However, the additional mechanical machining would not be recommended due to difficulty in clinical practice.…”

“…Elke and Rieker [ 41 ] reported that the estimated threshold for osteolysis-free volumetric wear is around 670 mm 3 . According to the wear testing results in the current study, the dry weight loss of the polyethylene-based spacers was less than that of the commercial cement spacers (Femur: 34.34 mg vs. 149.6 mg; Tibial: 18.78 mg vs. 226.0 mg) [ 24 ]. The volumetric wear of the novel spacer set in the current study, by calculating the average wear volume by loss of dry weight and density of the UHMWPE material (ρ = around 0.95 mg/mm 3 ), was only 55.92 mm 3 , lower than the reported osteolysis-free volumetric wear threshold.…”

“…The loading magnitudes were reduced to 50% to account for partial weight bearing conditions and the regular 180-day usage of the knee spacer [ 22 ]. Hence, the articulating cycles, which were defined within the guidance, were reduced to 5 × 10 5 cycles [ 23 ], as described in a previous biomechanical study by Mueller et al [ 24 ]. Six sets of femoral/tibial spacers were utilized for testing under wear conditions, while the other 2 sets were prepared as test controls (specimens were pre-soaked only, no wear loads were applied).…”

“…All specimens were then dried in a vacuum chamber (37 °C) to facilitate the quantification of the material loss due to spacer or cement wear. The results were compared to published data on commercial knee spacers to confirm the wear safety volume [ 24 ]. Test fluids were collected and stirred for approximately 2 min before extracting 2 mL of sample for further testing.…”

Radiopacity Enhancements in Polymeric Implant Biomaterials: A Comprehensive Literature Review

“…Spacers are a temporary treatment option for periprosthetic infection in two stage revision arthroplasty procedures and are normally loaded with antibiotics. , In the Copal Spacem (Heraeus Medical GmbH, Wehreim, Germany) articulating bone cement spacers, CaCO 3 (15 wt %) is used as a contrast agent . Articulating spacers anticipate the release of cement particles during sliding; thus, CaCO 3 is preferred over BaSO 4 because it is nontoxic and less hazardous in the body than Ba 2+ particles. , Furthermore, as CaCO 3 particles are soft and less abrasive, third body-induced wear is reduced. Müller et al observed a 64% reduction in wear in a CaCO 3 -containing spacer compared to a BaSO 4 -containing spacer from the same manufacturer.…”