Final answer:
The correct option is D. Loss of motion at the carpometacarpal (CMC) joint of the thumb can result in a significant functional impairment, generally within the range of 40% to 70% loss of hand function.
Step-by-step explanation:
The potential loss of total hand function with loss of motion at the carpometacarpal (CMC) joint of the thumb can be significant. The first metacarpal bone provides a freedom of motion that is essential for thumb mobility, which in turn is crucial for grasping, pinching, and manipulating objects. The CMC joint is a saddle joint allowing for multiplanar movement, which is integral to the hand's functionality. Therefore, if motion at this joint is lost, a reduction in hand function is expected.
Considering the importance of thumb opposition and grasping, a loss of motion at the CMC joint would lead to difficulties with these functions. The specific loss percentage might vary, but generally, it is considered to be within the range of 40% to 70% loss of function, making option D. 40% to 70% the most accurate answer. It must be noted, though, that the exact loss can depend on the individual and the nature of the impairment.