Bony Mallet Thumb Treated With the Ishiguro Extension Block Technique: A Case Report.

A bony mallet thumb is an extremely rare injury. An 82-year-old man fell from a standing height and injured his right thumb. Imaging examinations revealed a rare intra-articular fracture at the dorsal side of the base of the distal phalanx of the thumb called the bony mallet thumb. Conservative treatment was adopted initially; however, surgery was deemed necessary because of the redislocation of the bone fragment. Thus, the Ishiguro extension block technique was used, and three months later, satisfactory thumb function was achieved. The Ishiguro technique is a relatively simple procedure often performed for bony mallet fingers. The current case indicated that it can also be used to treat cases of bony mallet thumbs successfully.