According to one aspect, a surgical instrument arrangement according to the invention has a modular motor drive unit (1), which has a drive arrangement having at least one output element (10A, 10B; 100; 1000); and an instrument shaft (2), which can be detachably connected to the drive unit, and a drive arrangement having at least one input drive element (20A, 20B; 200; 2000), wherein the output arrangement and the drive arrangement can be coupled to each other by means of a mechanical interface which has at least one single-sided linkage (10A-20A; 10B-20B); a pin (100) and a cut-out, wherein the pin can be expanded in the cut-out radially, in particular elastically and/or by means of at least one separate body (100.1) and/or a gap is formed between the pin and the cut-out, which gap is wavy in the radial direction, and in which a radially displaceable, axially fixed intermediate element arrangement (100.7) is arranged; and/or a tilting lever (1000).