Aim: To evaluate the behaviour of two fast-setting polymethylmethacrylate (PMMA) cements CMW® 2G and Palacos® fast R + G, as reference: Standard-setting Palacos® R + G.
Methods: The fast-setting cements CMW® 2G and Palacos® fast R + G were studied, using standard-setting high viscosity Palacos® R + G as a reference. Eleven units (of two batch numbers) of each cement were tested. All cements were mixed as specified by the manufacturer and analysed on the following parameters: Handling properties (mixing, waiting, working and hardening phase) according to Kuehn, Mechanical properties according to ISO 5833 and DIN 53435, Fatigue strength according to ISO 16402, Benzoyl Peroxide (BPO) - Content by titration, powder/liquid-ratio by weighing, antibiotic elution profile by High Performance Liquid Chromatography. All tests were done in an acclimatised laboratory with temperatures set at 23.5 °C ± 0.5 °C and a humidity of > 40%.
Results: Palacos® fast R + G showed slightly shorter handling properties (doughing, hardening phase, n = 12) than CMW® 2G, allowing to reduce operative time and to optimise cemented cup implantation. Data of the quasistatic properties of ISO 5833 and DIN 53435 of both cements tested was comparable. The ISO compressive strength (MPa) of Palacos® fast R + G was significantly higher than CMW® 2G, resulting in ANOVA (P < 0.01) and two sample t-test (P < 0.01) at 0.05 level of significance (n = 20). Palacos® fast R + G showed a higher fatigue strength of about 18% mean (ISO 16402) of 15.3 MPa instead of 13.0 MPa for CMW® 2G (n = 5 × 106 cycles). Palacos® fast R + G and CMW® 2G differed only by 0.11% (n = 6) with the former having the higher content. The BPO-content of both cements were therefore comparable. CMW® 2G had a powder/liquid ratio of 2:1, Palacos® fast R + G of 2.550:1 due to a higher powder content. Despite its higher gentamicin content, CMW® 2G showed a significantly lower antibiotic elution over time than Palacos® fast R + G (n = 3).
Conclusion: Both cements are compliant with international standards and are highly suitable for their specified surgical indications, affording a time-saving measure without detriment to the mechanical properties.
Keywords: Antibiotic; Arthroplasty; Elution; Fast-setting; Fatigue; Polymethylmethacrylate; Viscosity.