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 resorba ble polymer developed on the basis of alkylene bis(dilactoyl)-methacrylate to improve the anchorage of osteosynthesis material in cancellous bone. Can cellous bone screws were inserted in bovine as well as in human vertebrae a nd human femoral condyles and were augmented with the new polymer or polyme thylmethacrylate (PMMA), respectively. Nonaugmented screws were used as con trols. A removal torque test, a dynamic fatigue test, and a pullout test we re performed. Augmentation with the new polymer increased the removal torqu e by 84% in human femoral bone. In the dynamic fatigue test of bovine verte brae, the removal torque after cyclic loading was 115% higher for the new p olymer compared to the nonaugmented controls. In the human vertebrae, the r einforcement with the new polymer increased the removal torque after dynami c loading by 114%. The augmentation with the new polymer increased the pull out force by 88% in bovine vertebrae and by 118% in human vertebrae in comp arison to nonaugmented screws. It was concluded that augmentation by the ne w resorbable polymer significantly enhanced the anchorage of bone screws in cancellous bone. The mechanical efficiency of the new polymer was comparab le to that of PMMA cement. (C) 2001 John Wiley & Sons, Inc.