[Properties and degradation of a new bioresorbable bone glue]. / Eigenschaften und Degradation eines neuartigen bioresorbierbaren Knochenklebers.

In trauma surgery gluing is an attractive method of bonding fractured bone, which is rapid and does not require the use of screws and plates. The purpose of this study was to analyze in vitro the properties of a new bioresorbable bone glue, and in vivo its structure and degradation. The newly developed bone glue is based on alkylenbis(oligolactoyl)methacrylates and employs a two-component initiator system. Starting components for synthesis are ethylene glycol, lactic acid and methacrylic acid. In vitro the solidified glue is degraded via hydrolysis of ester bonds. Degradation products are ethylene glycol, lactic acid and oligomeres of methacrylic acid. After the first week polymer pellets (MMA, HEMALA, ELAMA) showed a weight loss of 12%. From week 2-20 a linear weight loss of 1.5% per week, that is 40% after 20 weeks, was observed. The in vivo investigations of the ultrastructure of the glue revealed a transparent and homogeneous mass with large electron-tight vacuoles. Differences in structure and degradation were not observed. Degradation of glue by hydrolysis and phagocytosis, with good biocompatibility was demonstrated.

A new bioresorbable polymer for screw augmentation in the osteosynthesis of osteoporotic cancellous bone: a biomechanical evaluation.

The aim of the study was to assess the mechanical efficacy of a new resorbable polymer developed on the basis of alkylene bis(dilactoyl)-methacrylate to improve the anchorage of osteosynthesis material in cancellous bone. Cancellous bone screws were inserted in bovine as well as in human vertebrae and human femoral condyles and were augmented with the new polymer or polymethylmethacrylate (PMMA), respectively. Nonaugmented screws were used as controls. A removal torque test, a dynamic fatigue test, and a pullout test were performed. Augmentation with the new polymer increased the removal torque by 84% in human femoral bone. In the dynamic fatigue test of bovine vertebrae, the removal torque after cyclic loading was 115% higher for the new polymer compared to the nonaugmented controls. In the human vertebrae, the reinforcement with the new polymer increased the removal torque after dynamic loading by 114%. The augmentation with the new polymer increased the pullout force by 88% in bovine vertebrae and by 118% in human vertebrae in comparison to nonaugmented screws. It was concluded that augmentation by the new resorbable polymer significantly enhanced the anchorage of bone screws in cancellous bone. The mechanical efficiency of the new polymer was comparable to that of PMMA cement.