Nonunion of a Third Metatarsal Base Stress Fracture Injured During Cross-Country Skiing Treated by Osteosynthesis: A Case Report.

Stress fractures at the base of the metatarsal are classified as high-risk stress fractures. The second and third metatarsal are likely to occur in classical ballet and jumping sports. Among them, there are few reports of nonunion cases after fractures at the base of the third metatarsal. We present a rare case of nonunion of a stress fracture at the base of the third metatarsal injured during practicing cross-country skiing. A 15-year-old male high school top-level cross-country skier couldn't stand the pain on the dorsum of his left forefoot during training for six months. Radiographic examination and computed tomography showed a transverse fracture line at the base of the third metatarsal and an osteosclerotic lesion at the fracture site. He was diagnosed with nonunion of a stress fracture at the base of the third metatarsal. We performed osteosynthesis with a locking plate and grafted autogenous bone into the nonunion site. He was able to return to skiing at 4 months postoperatively. At 2.5 years after the initial surgery, he was able to participate in an international cross-country skiing competition. We experienced nonunion following a stress fracture at the base of the third metatarsal, possibly injured while practicing cross-country skiing. Osteosynthesis with the plate fixation technique using autogenous bone grafting was a useful treatment for the nonunion of a stress fracture at the base of the third metatarsal.