Taking the trapezium (bone at the base of the thumb) out without doing anything else will result in shortening of the thumb. The hand will be disfigured and your pinch strength will be greatly affected.

In fact there are actually two types of pinch: key pinch and tripod pinch. Key pinch is the finger hold you use to insert a key and turn it in a lock. Tripod or three-point pinch is the opposition of the index and middle finger against the thumb. You use the tripod pinch anytime you pull a tape measure out of its casing or pick up a bag of fast food.

You may not think much about losing your pinch strength but just try turning a key in the door, picking up a dime, or carrying a plate of cookies to the table without using some kind of pinch. And that's just a short list of all the things we use our strong, opposable thumbs for.