Emerging Modified Poly (Methyl Methacrylate) (PMMA) Bone Cements for Augmentation of Osteoporosis-induced Compression Fractures of Vertebral Bodies: Present Status and Future Prospects

Minimally-invasive vertebral body cement augmentation methods, notably percutaneous vertebroplasty (PVP) and percutaneous balloon kyphoplasty (PKP), are now well established as surgical modalities for treating persistent and/or severe pain arising from osteoporosis-induced vertebral body (VB) compression fracture(s). The essence of each of these procedures is the injection of a dough of a bone cement (almost invariably, poly methyl methacrylate (PMMA) cement) either directly into the fractured VB(s) (as in PVP) or into a space created in the fractured VB(s) (as in PKP). Only a few commercially-formulated PMMA bone cement brands are specifically indicated for use in PVP and PKP, among which are Mendec®Spine and Osteopal®V. Recognition of the many shortcomings of these brands, such as compressive modulus that is markedly higher than that of the contiguous cancellous bone, has spurred the formulation and characterization of a large assortment of new PMMA bone cements. A review of the literature on these cements, which, herein, are designated “emerging modified PMMA bone cements” (EMPBCs), is lacking. Additionally, only a few fatigue and clinical studies of EMPBCs have been reported. The purpose of this work was to present a comprehensive, detailed, and critical review of the literature on EMPBCs, and, hence, identify the most promising of these cements. Using appropriate keywords and guided by strict acceptance and exclusion criteria, a thorough search of widely-used scientific databases, such as Google Scholar and PubMed, was conducted, which led to selection of 40 relevant English-language articles on EMPBCs. Four particularly promising EMPBCs were identified, among which is one in which mineralized collagen particles were blended with Mendec®Spine. In addition, eleven shortcomings of the literature are presented, prompting several areas for future study. Among these areas are development of a standard for determining the in vitro compression-compression fatigue performance of EMPBCs and conduct of well-designed prospective randomized controlled trials.