Abstract: A prosthesis kit comprising an elongate prosthesis body (1) and a series of modular strips (2a, 2b, 2c) of different thicknesses which are suitable for being combined with the body to constitute assemblies of different widths (Da, Db, Dc). Each of the modular strips has a longitudinally extending dovetail section edge (e.g., a dovetail tongue 20) which is suitable for interfitting in a complementary dovetail section (e.g., a groove 13) provided on a side of the elongate body, in such a manner that the interfitting dovetail sections ensure that the assembled body and strip are mutually fixed against relative sideways displacement.