A 72-year-old man had clinical gradual hip pain in both hips for 1 year. He was diagnosed with osteonecrosis of the femoral head in both hips by X-ray. His X-ray presented Ficat-Arlet classification stage III for the left hip and stage II for the right hip (Figure 1). Seven months later, there was a sudden and progressive increase in pain in the left hip. X-ray showed marked, progressive collapse of the left femoral head and arthritis change of the acetabulum (Figure 2). He had no fever or any symptoms of infection; however, an investigation for infection was performed, due to acute-onset and rapid progressive radiographic changes. The results of his serum work-up were a white blood cell count of 10,370/muL, hematocrit of 37.9%, hemoglobin of 13 g/dL, polymorphonuclear neutrophils (PMN) of 70.7%, lymphocyte of 19.6%, eosinophil of 3.5%, monocyte of 5.7% and platelets of 500,000/muL. The erythrocyte sedimentation rate (ESR) was 66 mm/h (normal value, 0-15 mm/h), and the C-reactive protein (CRP) was 9.6 mg/dL (normal value, <0.6 mg/dL). Ultrasound of the left hip revealed minimal fluid in the hip joint. Hip joint fluid aspiration under ultrasound guidance was performed only on the left side for microbiology study and yielded negative results. The patient was scheduled for THA in the next 3 months due to tight surgical queue. Preoperative laboratory ESR and CRP decreased to nearly a normal value.
At the scheduled admission for THA, the patient was afebrile and had no sign of inflammation, with normal skin condition at the left hip joint. Cloxacillin (1 g) was used for prophylaxis against surgical site infection 30 min before starting the operation and continued for 3 days after the operation. Intraoperatively, there was collapse of the femoral head, with erosion of acetabular cartilage in addition to rice body synovitis. Soft tissue and bone samples were sent for microbiology and pathology assessment due to a suspicion of infection. Cementless THA was successfully performed using the standard technique (Figure 3).
The laboratory results were positive for acid-fast bacilli (AFB), negative for gram stain, negative for aerobic bacterial culture and negative for tuberculous culture. A pathological tissue diagnosis reported chronic inflammation, with an area of granulomatous inflammation.
Post-operatively, the patient received anti-TB drugs for 9 months: isoniazid, rifampicin, pyrazinamide and etambutol for the first 2 months and then isoniazid and rifampicin for 7 months (2IRZE/7IR regimen). Other TB work-ups, such as chest X-ray and 3 days of morning sputum for AFB, were negative.
After surgery, he was able to walk with full weight-bearing without gait support and able to do daily life activities as normal. At his latest follow-up visit, at 2 years, his clinical condition was good and his Harris hip score was 97. X-ray of his hips is shown in Figure 4.