The main cause of leg pain and fever may be an open trauma to the skin of the patient’s leg due to an external force. If the open trauma becomes infected, the patient may have leg pain and fever, and the skin around the open trauma will be red, swollen, hot, and painful, and the patient’s temperature will be elevated. A routine blood test can be done by collecting blood, and if there are elevated white blood cells, a definitive diagnosis can be made. In the treatment of open trauma should be given for dressing disposal, and at the same time apply anti-inflammatory symptomatic treatment. If the open trauma is more serious, surgical treatment can also be taken for debridement, and sensitive antibiotics need to be applied and symptomatic treatment should be given in the postoperative period. If the patient suffers from hematogenous osteomyelitis, pain and fever can also occur, and the pain is more severe, and the patient may have a low-grade fever.