Seeley Stacy K, Seeley John V, Telehowski Paul, Martin Sidney, Tavakoli Massoud, Colton Stephanie L, Larson Bryan, Forrester Patricia, Atkinson Patrick J
Department of Science and Mathematics, Kettering University, 1700 West Third Avenue, Flint, MI 48504, USA.
Clin Orthop Relat Res. 2004 Mar(420):298-303. doi: 10.1097/00003086-200403000-00042.
Polymethylmethacrylate bone cement beads impregnated with antibiotic are a common treatment for patients with persistent articular joint infections or osteomyelitis. They also are used as a prophylaxis for infection in patients with large soft tissue wounds. The current study was designed to evaluate the relationship between bead geometry and elution of the antibiotic tobramycin by methodically varying the shape of the beads for a given set of volumes. Beads of five shapes (spherical to ovoid) and two volumes were prepared and studied. Only 0.9% to 3.3% of the total amount of tobramycin present actually eluted from the beads in a 96-hour period and of this amount, approximately 1/3 eluted within the first 4 hours. The elution mass data indicate the benefit of numerous, small and elliptically shaped beads for maximal antibiotic availability. Additionally, a mathematical model is presented that describes these findings and can be used to predict tobramycin delivery rates from bone cement beads. This model assumes that the antibiotic is delivered through two mechanisms: fast dissolution of tobramycin initially adhering to the bead surface and slow release by diffusion through the polymer. The results generate diffusion coefficients for tobramycin in polymethylmethacrylate bone cement on the order of 2 x 10 cm/s.
浸渍抗生素的聚甲基丙烯酸甲酯骨水泥珠是治疗持续性关节感染或骨髓炎患者的常用方法。它们也被用作预防大面积软组织伤口患者感染的手段。本研究旨在通过系统改变给定体积组的珠子形状，评估珠子几何形状与抗生素妥布霉素洗脱之间的关系。制备并研究了五种形状（球形至卵形）和两种体积的珠子。在96小时内，实际从珠子中洗脱的妥布霉素总量仅为0.9%至3.3%，其中约1/3在最初4小时内洗脱。洗脱质量数据表明，众多小的椭圆形珠子有利于最大限度地提高抗生素的可用性。此外，还提出了一个数学模型来描述这些发现，并可用于预测骨水泥珠的妥布霉素释放率。该模型假设抗生素通过两种机制释放：最初附着在珠子表面的妥布霉素快速溶解，以及通过聚合物扩散缓慢释放。结果得出妥布霉素在聚甲基丙烯酸甲酯骨水泥中的扩散系数约为2×10⁻⁹cm²/s。
