Jakub Szabelski, Robert Karpiński
The main objective of this systematic review was to synthesise current knowledge on tricalcium phosphate (TCP) as a functional modifier of poly(methyl methacrylate) (PMMA)-based bone cements, relating the microstructure of PMMA/TCP composites to their mechanical, biological and functional (handling) performance. Web of Science, Scopus and PubMed were searched for 2010-2025. Studies reporting primary quantitative data on PMMA cements specifically modified with TCP were eligible. Over one hundred records were screened by two independent reviewers, yielding 15 studies appraised qualitatively and combined by narrative synthesis. The evidence links polymerisation of the PMMA matrix, calcium and phosphate ion release from TCP, apatite-layer precipitation, and cell-mediated TCP resorption coupled to bone remodelling. TCP, especially β-TCP or biphasic calcium phosphate systems, can balance mechanical stability with bioactivity: moderate β-TCP contents (of the order of 10 wt% for solid cements under quasi-static compression) preserve clinically acceptable properties while enhancing osteoconductivity, though this limit falls for porous, α-TCP-containing and fatigue-loaded formulations. Porosity, TCP amount, crystalline form and particle size are the governing microstructural variables. The evidence is limited, dominated by in vitro and short-term static tests, with heterogeneous formulations and no controlled clinical data, so benefits should be interpreted qualitatively rather than as firm quantitative relationships. The review was not registered; this research received no external funding.