For many people, a hook device appears old, and a prosthetic hand modern.

That notion is very clearly wrong.

• Split hooks usually allow for a far better approach and grip angle than many prosthetic hand designs [link]. This goes deeper into designing sensible shapes for an amputee’s everyday use. A prosthetic hand that allows for better grip angles usually will require the gripper shape to be a bit like a split hook. The thumb and index finger may have to have an almost equal length, and so the akward looking (but relatively nice to use) conventional Otto Bock hand shapes resulted, where no normal glove can be fitted.
• Split hooks really are a more modern development [link]. Good split hooks have a highly evolved shape, which definitely cannot be said about many prosthetic hands. With exception of the also extremely evolved Becker hand, most modern prosthetic hands could benefit from some more shape improvements.
• Split hooks are the typical grip device for body powered arms. and they can be very, very fast [link]. Myoelectric arms may be a better choice for more serious degrees of impairment – but for the otherwise perfectly mobile, unilateral below elbow amputee, with a long stump, a body-powered arm has capacities and potentials to offer functionalities far, far beyond what myoelectric technology may offer.
• Split hooks embody a transhumanist ideal [link:demo] [link:theory]. Prosthetic hand designs do not, they are outdated and conventional in terms of iconoclastic, modern design or radical improvement approaches. It is funny that this should come from a traditionalist.
• Split hooks are also lighter despite being more robust, if not far more robust.
• It is easily possible to add soft cover material for grip enhancement to split hooks or grippers, by adding cheap silicone tubing or other materials [link]. The same cannot be said for practically all prosthetic hands – soft covers are not at all available or cost an absolute fortune.
• It is easily possible to vary grip force / cable force of split hooks, most have rubbers to put on or take off. The TRS Jaws has a lever to change grip force. Prosthetic hands usually lack that feature.
• For body powered devices, split hooks are the ultimate and best in probably most dedicated and focused grip perfection and control reliability. For myoelectric devices, there is no such thing, unfortunately, particularly with myoelectric control error rates at large since over fourty years [link]; one could believe that research predicted improvements within the next 5-10 years or so, since four decades. Who knows, maybe in the next 5-10 years, otherwise, who knows.

So from my view, myoelectric stuff is junk, and body-powered split-hooks win [link].

But can you see that, too? Is there a visual aspect to cover on top of all that? See the two animated images down there.

• The prosthetic hand, here a Becker Imperial hand, works perfectly well with regard to its precision grip. There is no better really. But this shows where prosthetic hand shapes all are problematic: their shape obstructs the view. The extra materials are easily classified as dead weight, if one is not necessarily forced to wear a prosthetic hand for any reason. This puts extra burden on the grip itself, where the Becker hand shines, due to a very repeatable well crafted precision grip. Many other prosthetic hands have deficiencies there.
• The prosthetic hook does not at all have that problem. I can see through the highly skeletonized shape of the hook. That is why grippers and hooks are the hottest latest shape design that provide what we really need: concentrated, amalgamated, focused, shrunk, skeletonized, reduced sleek elegant grippers or hooks, not dead weight.

If you spend all day with these devices, who knows, maybe you notice these aspects more often, really, I find that very hard to tell what your perspective is on that.

The same goes for typing on a keyboard, where the added / extra fingers usually tend to get in the way where one cannot see, mostly regardless of hand design.

If you want the explanations, all out, then check here [link].