ION-RELEASING INORGANIC PHASES IN OSTEOCHONDRAL SCAFFOLDS AND THEIR REGION SPECIFIC REGENERATIVE EFFECTS

Abstract

Osteochondral defects affect tissues with distinct matrix compositions, cellular environments, mechanical properties, and healing capacities. Scaffolds intended to repair these defects must therefore support cartilage formation, maintain a functional transition across the calcified interface, and promote subchondral bone repair. Inorganic phases can provide mineral and structural cues while releasing ions that influence local cell behaviour. However, their effects depend on the phase’s composition and location, the amount and timing of ion release, and the surrounding scaffold architecture. This review examines ion-releasing inorganic phases used in osteochondral scaffolds, including bioactive glasses, calcium phosphates, ion-substituted apatites, and silicate-based ceramics. The literature is considered across the cartilage, calcified-interface, and subchondral-bone regions, with attention to ion-release characteristics and reported biological outcomes. The review also discusses multifunctional designs that combine mineral cues with features such as controlled release, immunomodulation, or external stimulation. Although preclinical studies report promising region-specific responses, comparisons remain difficult because release-testing methods, experimental controls, outcome measures, and follow-up periods vary. Future studies should report phase location and release profiles alongside region-specific biological and mechanical outcomes. This may help clarify when ion-releasing designs support integrated osteochondral repair.