Dr. Rob Pettitt, an orthopedic veterinary surgeon at the University of Liverpool, said the deformity has been seen in dogs but never before in chimpanzees.

The 3-year-old chimp called Janet was rescued from the Cameroon pet trade last year and lives in a chimpanzee reserve supported by the Cameroon Wildlife Aid Fund. Janet was unable to climb and had difficulty walking because a bone in her forearm -- the ulna -- had stopped growing.

"Surgery to correct the condition in dogs is less complex than the procedure in chimps," said Pettitt. "The first step was to remove the far end of the ulna, which had become compacted due to the continued growth of the radius."

He said a triangular section of bone was then removed from the radius in order to straighten the limb and a plate was inserted to secure the two ends of the bone.

Officials at the chimpanzee reserve, said Janet has rejoined her group at the reserve and X-rays show the surgery was a success.