Evaluation of elution and mechanical properties of two injectable chemotherapeutic bone cements

Chemotherapeutic bone cements can both stabilize the bone fractures as well as deliver chemotherapy agents directly to the bone metastatic site and adjacent soft tissue tumors. This study evaluated the in vitro elution and flexural properties of Vertebroplastic™ and Confidence Ultra™ bone cements (Depuy Spine Inc., Raynham, Mass., USA) containing methotrexate. In vitro elution was measured by placing bone cement specimens containing 4 different methotrexate amounts in 20 ml saline, and the methotrexate elution was measured at regular intervals for 672 h. The flexural properties of bone cement containing 2 different initial methotrexate amounts after storage in physiological saline were measured using a 3-point bending test. The drug elution rate depended on the initial methotrexate amount added and the type of bone cement used. The relationship between the initial drug amount added and the drug elution rate was not linear. Methotrexate elution decreased the flexural modulus and strength of specimens; this decrease was not proportional to the initial amount of methotrexate added. The results show that bone cements are well suited for use with chemotherapy agents. However, the elution and mechanical properties of each bone cement-drug amount combination should be thoroughly quantified in vitro before using such a combination in a clinical setting.