Biomechanical augmentation of locked plating system in osteoporotic proximal humeral fractures using novel bioactive cement

Abstract

INTRODUCTION: The fixation of osteoporotic proximal humeral fractures by locking plate can be augmented by local filling of bioactive bone cement. This study aimed to test if local filling of a novel strontium-containing hydroxyapatite (Sr-HA) bone cement can improve the outcomes of fixation of a locking plate system in a cadaveric proximal humeral fracture model. METHODS: A total of 12 pairs of formalin-treated cadaveric humeri were used. One side of 6 pairs was for the cemented group while the other side as control group. The bone mineral density (BMD) of all samples was tested. A 3-part-facture model was created, reduced, and fixed by the proximal humerus locking plate. In the control group, the screw holes were not filled by cement. The Sr-HA bone cement were filled in study group. Locking screws were inserted in a standard manner before the cement hardened. Mechanical studies including varus bending test and axial rotational test were performed. RESULTS: The median BMD of all specimen was 0.528 g/cm3. Better mechanical outcomes were found in the cemented group. Statistically significant difference between the cemented and the control groups was found in the varus bending test, but not in the axial rotation test. CONCLUSION: The local filling of Sr-HA bone cement enhances fixation of the proximal humeral internal locking system locking plate in cadaveric proximal humeral fracture model. The improvement is found statistically significant in the varus bending test but not in the axial rotation test.