The patient is a 33-year-old Chinese male. He was diagnosed with brucellosis in a local hospital in October 2017 due to right hip pain and wavy fever. Following the administration of anti-brucellosis drugs, the fever subsided, but the pain in the right hip did not. In January 2018, the patient visited the orthopedic department of our hospital due to aggravation of right hip pain and decreased hip joint mobility. History indicates that the patient's family raised sheep for a long time, and there was no history of trauma, alcohol consumption, or hormone use. The physical examination revealed severe tenderness in the right hip region, longitudinal percussion pain in the right lower limb, and limited passive and active movement of the right hip. There was no abnormality in the chest X-ray or CT. X-ray of the hip joint showed low signal on the right femoral head, joint narrowing and even invagination of the joint space (Figure 3A). CT showed cavity necrosis and low-density patches of shadows in the right femoral head (Figure 3B). MRI of the hip joint indicates effusion of the right hip joint complicated by necrosis of the right femoral head, and the inflammatory fluid diffused with extra-articular (Figure 3C). Blood tests indicated WBC 4.60x109/L with neutrophils accounting for 61.1%, CRP59.3mg/L, ESR29.0mm/hr, and procalcitonin (PCT) 0.05ng/mL. T-SPOT.TB assay (T-SPOT), as well as serum anti-tuberculosis antibody tests, were negative. RBPT was positive, and SAT was positive at a titer of 1:640. The above examination eliminated tuberculosis, and a preliminary diagnosis of brucellar hip arthritis and osteonecrosis of the femoral head was made. Despite taking anti-brucellosis medications for two weeks, which included rifampicin (0.6g po qd; Guangdong Hengjian Pharmaceuticals), doxycycline (0.1g po bid; Jiangsu Lianhuan Pharmaceuticals), and levofloxacin (0.2g ivgtt bid; Yangtze River Pharmaceuticals), the right hip's symptoms did not improve. This patient underwent puncture and irrigation of the right hip joint and core decompression with bone grafting of the femoral head. Using real-time PCR, B. melitensis was detected in joint effusions and osteonecrosis of the femoral head. HE staining in osteonecrosis of the femoral head revealed partial dead bone and inflammatory cellulose exudate (Figure 4A); Giemsa staining showed scattered positive Brucella (Figure 4B). When discharged from the hospital three weeks after surgery, the patient's right hip pain was significantly reduced; blood tests showed a CRP level of 24.7mg/L and an ESR level of 18.00mm/hr. The antibiotic regimen was adjusted to rifampicin (0.6g po qd; Guangdong Hengjian Pharmaceuticals) and doxycycline (0.1g po bid; Jiangsu Lianhuan Pharmaceuticals) after discharge, with a total therapy duration of six months. Following a follow-up four years later, the pain in the right hip had completely disappeared, and the hip joint was no longer limited in movement; neither the blood tests nor the imaging examinations (Figure 3D-F) revealed any abnormalities.