An all-in-one injectable biocement: self-setting magnesium phosphate for bone repair, fracture adhesion and osteoporotic fixation

TL;DR

A new injectable magnesium phosphate cement is developed for bone repair, offering better biodegradability, bioactivity, and mechanical strength compared to traditional cements.

Contribution

The development of an injectable magnesium phosphate cement with synchronized degradation and bone formation.

Findings

MPC promotes bone regeneration through sustained release of osteogenic Mg2+ ions.

MPC shows strong adhesion to various substrates and enhances screw fixation stability in vivo.

In vitro studies confirm enhanced cell migration and mineralized matrix deposition with MPC.

Abstract

Conventional bone cements face critical limitations in biodegradability, bioactivity and mechanical compatibility. To overcome these challenges, an all-in-one injectable magnesium phosphate cement (MPC) is engineered for bone repair, fracture adhesion and osteoporotic fixation. This functional platform integrates rapid self-setting, high early compressive strength and controlled degradation synchronized with bone formation. Unlike bioinert poly(methyl methacrylate) or slow-degrading calcium phosphate cements, MPC offers a superior bioactive alternative. It promotes bone regeneration through the sustained release of osteogenic Mg2+ ions, which accelerate osteoblast differentiation and angiogenesis. Comprehensive characterization confirms MPC’s dense microstructure, mild exothermic reaction, physiological pH stability and biocompatible degradation, eliminating risks of thermal necrosis or toxic ion accumulation. The MPC demonstrates outstanding initial mechanical properties under in vivo-like conditions characterized by a warm and humid environment. In vitro studies show that MPC significantly promotes cell migration, upregulates the expression of osteogenic markers and enhances mineralized matrix deposition. Its controlled degradation behavior sustainably releases osteogenic Mg2+ ions, which orchestrate the proliferation of bone marrow stromal cells and facilitate RUNX2-mediated osteogenic differentiation, collectively accelerating the mineralization process. In vivo evaluations further reveal multi-functional bone regenerative capabilities: MPC dynamically guides defect repair through degradation-coupled bone ingrowth, achieving seamless integration without interfacial gaps, and significantly augments screw fixation stability via robust osseointegration. With exceptional adhesion to diverse substrates (tantalum, PLA, bone; 5.5× stronger than CPC on PLA) and intrinsic safety, MPC establishes an advanced platform for orthopedic regeneration and fixation.

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