outer shell may be formed from hydroxyapatite calcium phosphate or any other biodegradable material that will dissolve and or fuse within the bone preferably the rear end 46 of shell 40 is formed as a relatively thin membrane that can be pierced by tip 27 of needle 18 a further thin membrane 44 may be formed between the outer shell 40 and the medicament 42 in use the cartridge 12 is positioned within retaining member 14 as shown in fig2 with the forward end 21 of shaft 16 contacting the rear surface 46 of the bone implant 12 actuation of trigger member 36 causes the shaft 16 and the needle 18 to slide forward retaining member 14 is preferably formed from a flexible material such as rubber plastic or the like so that forward movement of shaft 16 pushes the cartridge 12 out of the open front end of the retaining member 14 for deployment thereof into the bone fracture or other damaged or diseased area as the shaft 16 pushes the cartridge 12 out of the retaining member 14 the tip 27 of needle 18 pierces the thin membrane 46 to release the medicament 42 into the fracture the surgeon lodges the pierced cartridge 12 within fracture f or the degenerative bone tissue in fig9 retaining member or head 14 of fig4 has been replaced by an alternative head 214.