Instruments that take impact form a separate group in orthopedic sets. The edges of osteotomes and chisels need regular sharpening; a blunt chisel cracks bone instead of cutting it and forces the surgeon to strike harder. Keeping to the original sharpening angle matters if the instrument is to behave the same way.

In prosthesis sets the instruments are tied to the implant system, and some items become unusable when the system changes. Separating system specific parts from general purpose instruments when composing a set makes it possible to renew only the part that changed. Keeping unused instruments in a set needlessly increases both counting and sterilisation load.