An unusual pathogen for prosthetic joint infection

Abstract

In 2012, an 84-year-old Chinese man presented with progressive, chronic left atraumatic knee pain and swelling. His medical history was notable for pulmonary tuberculosis treated in China in 1951 and rheumatoid arthritis diagnosed in 2006. His joint pain progressed despite use of disease modifying drugs and steroid injections. Antitumor necrosis factor inhibitors were not used because of concerns of tuberculosis reactivation. Clinical examination showed he had antalgic gait, knee eff usion, stiff ness, and joint-line tenderness. Laboratory results included erythrocyte sedimentation rate of 88 mm/h and C-reactive protein of 205 mg/L. Radiographs showed severe tri-compartmental degenerative arthritis (fi gure A). The patient underwent total knee arthroplasty in August, 2012 (fi gure B). Extensive synovitis was noted and pathological examination showed granulomatous infl ammation (fi gure C). Staining of synovial tissue for acid-fast bacilli and tuberculosis PCR were negative. The patient’s knee symptoms initially improved, but 5 months after total knee arthroplasty he developed a draining sinus from the knee incision. He underwent irrigation and debridement of the knee with exchange of the polyethylene tibial insert. Initial synovial tissue fl uid cultures were negative, but subsequent acid-fast bacilli cultures from synovial tissue and joint fl uid grew Mycobacterium tuberculosis. Sputum cultures were negative for pulmonary tuberculosis. He started a course of antituberculosis therapy including rifampicin, isoniazid, pyrazinamide, and ethambutol for treatment of tuberculosis prosthetic joint infection in February, 2013. He was advised to undergo a two-stage resection-revision arthroplasty but declined further surgery and thus an implant retention strategy was pursued. The patient completed 12 months of antituberculosis therapy in February, 2014. He has since continued rifampicin and isoniazid treatment with a plan for long-term suppressive therapy in the setting of retained prosthesis. At his latest follow-up, 2 years after initial diagnosis of tuberculous prosthetic joint infection, the incision had healed without clinical sign of infection and his knee has a pain-free range of motion from 0–95°. Tuberculous arthritis accounts for 1–5% of people with tuberculosis. Scarce data are available for optimum management of tuberculous prosthetic joint infection. This case illustrates an unusual reactivation of tuberculosis in an isolated extra-pulmonary site after joint replacement surgery. Prompt initiation of antituberculosis therapy might enable implant retention, although continuation of suppressive therapy might be needed. In the setting of globalisation and the increasing use of immunomodulatory therapies and joint replacement surgeries, this case illustrates the need for tuberculosis to be thought about early in the diff erential diagnosis for culture-negative prosthetic joint infection in patients with previous exposures or epidemiological risk factors.