A second operation is the trapeziometacarpal interposition arthroplasty (TMIA). Only part of the trapezium is removed. Then, part of the flexor carpi radialis tendon is used to reconstruct the thumb. Some of the same tendon is also placed inside the spot where the piece of bone has been taken out.
By taking out the whole bone, LRTI comes with a slight risk that the thumb will shorten as the bones move up toward the hand. This process is called proximal migration of the thumb. The idea behind the TMIA is to reduce this risk by leaving a portion of the bone in place.
And in fact, studies show that there's a good chance of proximal migration in those patients who have had a LRTI compared with a TMIA. However, it doesn't appear that the shortening has any functional significance. There is a decrease in pinch strength after this operation but it's the same amount with either the LRTI or the TMIA.
Loss of function after thumb reconstruction is to be expected. This is true no matter how the operation is done. With time and a good hand therapy program, your father should be able to get back to his woodcarving. It may even be an excellent form of therapy!