Osteomyelitis is divided into acute and chronic. Acute osteomyelitis often appears within 2 weeks of onset and is difficult to diagnose in the absence of obvious symptoms (timely and heavy use of antibiotics), and often many migrate to chronic osteomyelitis. Eighty percent of the patients we see have chronic osteomyelitis. Therefore, we focus on chronic osteomyelitis. The basic symptoms of chronic osteomyelitis are localized redness, swelling, elevated skin temperature, and pain. The pressure pain at the lesion is the most obvious. If left untreated, skin sinus tracts may develop, the wound may remain open for a long time, purulent exudate will continue to flow (in some cases the swelling and pain will be relieved by the flow of pus), and small pieces of dead bone may occasionally drain. Sometimes the wound will temporarily heal, but because the focal point of infection still exists, it can have another acute attack, which can be accompanied by systemic symptoms (such as fever, chills), local redness and swelling. The chance of recurrence is very high, especially if the patient’s health condition deteriorates or immunity decreases. The interval between recurrences can be very long, and we have had patients who had recurrences after 33 years. Recurrent inflammation, repeated skin breakdown and healing, and the possibility of cancer. The long-term condition can lead to atrophy of limb muscles and osteoporosis. In severe cases, pathological fractures, limb shortening or angular deformity may occur; if the onset is close to the joints, there are mostly joint contractures or stiffness. Patients may have elevated white blood cells, neutrophils, C-reactive protein, and blood sedimentation in blood tests during acute attacks. Patients with tuberculosis may have a positive T-spot test. Because chronic osteomyelitis is a wasting disease, the nutritional status of many patients is poor, with albumin mostly below 30 g/L, and even below 25 g/L. X-rays may show dead bone and a large amount of denser new bone formation, and the bone is generally coarse and dense with occlusion of the bone marrow cavity. Sometimes there are cavities, and in the case of war injuries, shrapnel may be present. The diagnosis of osteomyelitis is mainly based on the patient’s history + the above symptoms + imaging.