Abstract
Introduction: A novel device for two-stage septic revision of TKA was checked to evaluate for mechanical and pharmacological properties. Methods: The articulated knee spacer is a temporary device made entirely of gentamicin bone cement industrially preformed and available in 3 sizes. It maintains joint space and motion, allowing partial weight-bearing. It provides an in situ release of antibiotic. Static and dynamic mechanical testing was performed according to ISO/DIN 14243-1. Surface rugosity was assessed according to DIN 4768. Pharmacological behaviour was evaluated according to the European Pharmacopoeia. Results: Static mechanical testing: the device resists a load > 10000N (physiological load peak = 2500N). Dynamic mechanical testing: no breakage after 500.000 cycles at 1300N (half load for physiological knee joint). Wear produced by the PMMA-PMMA coupling is not much higher than wear produced by PE-metal coupling. Surface rugosity (polishing effect) decreases of an order of magnitude after 8 weeks of implantation, and no difference is found between 8 weeks and 5 months of implantation. The in vitro gentamicin release in 7 days is around 2% of the initial amount of antibiotic and ranges from 15 mg (small) and 35 mg (large). Conclusions: The articulated knee spacer has excellent mechanical properties comparable to standard prostheses, which guarantee safety of use for the time of implantation foreseen (up to 6 months). As an ancillary property it delivers locally a high concentration of gentamicin.
Theses abstracts were prepared by Professor Dr. Frantz Langlais. Correspondence should be addressed to him at EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
