correction required by virtue of the compression fractures finally the fill opening 27 is closed to prevent egress of inflation material 19 fig1 15 show a form of the invention in which a balloon 30 and catheter tube 32 is employed the balloon 30 is surrounded by an expandable fabric bag 22 to protect the balloon 30 from being punctured during the inflation steps and to remain in place to prevent undesired egress of material injected into the cavity formed in the bone balloon 30 may be any medical grade elastomeric balloon the balloon 30 may be constructed from latex urethanes thermoplasic elastomers or other substances suitable for use as an expandable member examples of suitable balloons include but are not limited to balloons utilized with the fogarty u00ae occlusion catheter manufactured by baxter healthcare corporation of santa ana calif balloons of the type described u s pat no 5 972 015 to scribner et al and others the methods involve placement of the expandable fabric bag 22 of the invention about the balloon 30 of the scribner et al device the expandable bag 22 is left in place before the cavity 16 is filled with bone substitute or bone cement the expandable fabric bag 22 prevents breakage of the balloon 30 and greatly limits the ability of fill material from leaking out of the cavity through bone fissures where it could cause damage as may best be seen in fig1 13 and 15 the bag 22 may include a neck 29 which extends outwardly from the bag 22 to completely overlap the shape of balloon 30 the bag.