ObjectiveThe incidence of fractures in pregnancy and lactation-associated osteoporosis (PLO) is very low. Some fracture cases of PLO are associated with vertebral compression fractures, while malleolar fractures in patients with PLO are rarely reported before.Case reportA 31-year-old Han Chinese patient presented with a malleolar fracture 3 months after delivery, while she was still breastfeeding. Temporary closed reduction and plaster external fixation were performed in the emergency room. Then the patient was admitted to the orthopedic trauma ward for surgery and diagnosed as PLO by dual-energy X-ray absorptiometry (DEXA). After preoperative evaluation, the patient underwent open reduction and internal fixation. With the diagnosis of PLO, the patient was treated with weaning, bisphosphonate, and supplementation of calcium carbonate and vitamin D. During the 12-month follow-up period, the results of DEXA and laboratory examination improved gradually, and the internal fixation was removed 12 months after surgery.ConclusionOrthopedic doctors should not ignore the possibility of PLO to avoid misdiagnosis of perinatal women with fractures. Improvement of functional recovery of fractures can be achieved with accurate diagnosis and individual treatment.