In October 2001, a 33-year-old Caucasian female office employee visited our orthopedic outpatient clinic, with complaints of chronic pain in the left hip since 1997. Her medical history showed two episodes of pleuritis and infertility problems. The patient lived a healthy life; non-smoker and 2 units of alcohol per week. Her length was 1.68 m and her weight approximately 67 kg. In both episodes of pneumonia Ziehl-Nielsen staining showed no tubercles in pleural effusion. In order to find an explanation for her infertility the patient had undergone a laparoscopy in 1999. Intra-abdominal granulomas, adhesions and signs of chronic peritonitis were found. Ziehl-Nielsen and periodic acid-schiff staining (PAS staining) of peritoneal effusion and granulomas did not show acid fast bacilli. One year previously a clinical analysis of her hip complaints was performed on the rheumatology department of another hospital. There, the hip had been visualized by CT scan, MRI and skeletal scintigraphy, but no diagnosis had come up. Rheumatologic blood testing and Mycoplasma serology had been negative. Ziehl-Nielsen staining of pus aspired from the hip had been negative for acid fast bacilli, culture had been negative for Mycobacterium tuberculosis as had polymerase chain reaction. When the patient first visited us, her walking distance was limited to thirty minutes with crutches. No other joints were affected. No fever, nocturnal sweating or weight loss was present. On physical examination, there were no symptoms of infection. All hip joint movements were limited and painful (flexion 80Â°; abduction 20Â°; adduction 10Â°; internal rotation 0Â°; external rotation 0Â°). Hematological blood testing revealed a total white blood count of 9.4/cu mm. and ESR of 30 mm in the first hour. Conventional hip radiography showed some osseous destruction of the joint with narrowing of the joint space, suggesting loss of articular cartilage. A review of the earlier made MRI revealed osteonecrosis, destruction of the hip joint, periarticular oedema, and multiple fluid collections, and with these features and the abdominal granulomas in mind the suspicion of articular tuberculosis arose. Additional chest radiography did not show any abnormalities. We decided to perform an open biopsy to obtain a diagnosis. At surgery, granulation tissue and destruction of the cartilage of the femoral head was seen, also suggesting articular tuberculosis. In comparison with the earlier made MRI, which showed some acetabular destruction, there was progressive destruction of the superior part of the acetabulum which had resulted in a large local osseous defect and superior migration and lateralization of the femur. Our goal was to fill the acetabular osseous defect by in situ ankylosis of the femoral head, instead of performing the classical Girdlestone resection arthroplasty. After soft tissue debridement, the left hip was immobilized in a hip-spica cast. Ziehl-Nielsen staining of the debris was positive for acid-fast bacilli. A Mantoux-test was performed, which was strongly positive. The patient was treated with tuberculostatics (Isoniazid, Rifampicine, Ethambutol and Pyrazinamide) for 12 months. Filling of the acetabular defect resulting from ankylosis with the femoral head occurred approximately 4 months after initiation of chemotherapy and immobilisation. After fusion, shortening of the left leg and an intentional flexion position of 20Â° were present. From then the patient was mobilized without crutches. In November 2003, two years after the index operation, a primary one-stage cementless total hip arthroplasty was performed (OsteonicsÂ© Total Hip System, Stryker USA). Histopathological examination of the retrieved bone and joint capsule showed no signs of tuberculosis. Therefore, postoperatively she did not receive any tuberculostatics. No peri or postoperative complications occurred. At the latest follow up in March 2008, 52 months after total hip replacement, no signs of reactivation of the tuberculosis were present. The patient experienced no pain and had a normal range of motion. She did not suffer from any significant limitations in her daily activities, including sports and labour. The bone that formerly belonged to the femoral head, had fully integrated with the acetabulum. Radiological assessment of the left hip showed no signs of loosening.