Angular deformity of the thumb from abnormal triangular epiphysis isn't a common problem. There are a few studies of children who have had corrective surgery and the results.

Some surgeons recommend taking out the abnormal epiphysis (growth plate). Careful removal of the cartilage is required with this surgery. Others suggest a partial excision of the odd-shaped bone for a better correction of the deformity.

Corrective wedge-osteotomy is another option. A pie-shaped piece of bone is inserted or wedged into the bone to tilt the bone in the opposite direction.

There are some problems with each operation. Removing the cartilage can result in early arthritis. Wedge-osteotomies can overcorrect the thumb causing a tilt in the opposite direction. Or the deformity can be undercorrected and the child ends up with a permanent tilt anyway.

Surgery before age five is best. It gives the bone and joints a chance to adapt and avoids shortening of the bone and narrowing of the joint.