There is provided an admixture comprising morsellised bone particles and particles of water-soluble biodegradable glass. The particle size distribution and diameter range is pre-selected to produce an aggregate. Addition of the glass enables an admixture having aggregate characteristics and thus increased shear strength to be produced whilst simultaneously enabling bone regeneration to occur within the treated defect. The admixture is therefore useful in the repair of bone defects, especially primary joint arthroplasties, such as hip replacement operations.