Ortho Dx: Atrophy to the first dorsal web space of the hand

A 56-year-old man presents with several months of progressive weakness of the right hand. He works in construction and has had difficulty grasping objects. On examination, atrophy to the first dorsal web space is seen, as shown in the image.

This case has been brought to you in partnership with the Journal of Orthopedics for Physician Assistants.