The present invention includes hyaluronic acid complexes of a monovalent alkali metal salt of hyaluronic acid and a tetra alkyl ammonium halide that are suitable for incorporation with tissue scaffolds that are suitable for use in repair and/or regeneration of muscoloskeletal tissue and that include a biodegradable, porous substrate made from a biodegradable, hydrophobic polymer, where the hyaluronic acid complex is substantially insoluble in water at room temperature, yet soluble in mixtures of organic and aqueous solvents in which the selected hydrophobic polymer is soluble.