In Princes of the Apocalypse the following item exists:
Claws of the Umber Hulk:
[...] While wearing the claws, you can't manipulate objects or cast spells with somatic components.
- Princes of the Apocalypse (page 222) Magic Items
This item does not actually say it prevents you from grappling, but the requirements to grapple are as follows:
[...] Using at least one free hand, you try to seize the target by making a grapple check instead of an attack roll [...]
Do you still have a free hand while wearing both of the items above (left hand and right hand)?