We report a case of avulsion fracture of the calcaneus in an 83-year-old woman. Nonoperative treatment was not considered satisfactory. However, the os calcis was osteoporotic, and internal fixation therefore was performed with a transverse Kirschner pin through the os calcis, securing a figure-of-8 metal tension band wiring to the fragment. We suggest that this technique provides a strong internal fixation in selected cases.