Objective

The loosening of total joint replacement is a frequent complication after total hip arthroplasty (THA). Septic osteolysis should always be feared. We report here a rare case of hip arthroplasty infection due to Mycobacterium bovis after Bacillus Calmette-Guerin (BCG) therapy in a context of bladder cancer.

Observations

A 70-year-old man was referred to the department of rheumatology in September 2015, because of a total functional disability of the left lower limb. He underwent an un-cemented left total hip arthroplasty in 2003 for the treatment of osteoarthritis. We noted a bladder carcinoma treated by BCG instillation in 2013. Concerning his lower-limb, the activity-related pain has progressively intensified. No fever, weight loss, night sweat or other constitutional symptoms had been noticed. The medical examination showed an isolated painless mass in the inguinal fold. Initial x-ray showed a large trochanteric bone defect and a medial femoral cortex osteolysis. A CT-scan revealed a mass located between the acetabulum and the femoral vasculo-nervous package. A puncture of the mass yielded a hematic and purulent material. On day 14 of incubation, a BCG Mycobacterium bovis strain developed on a specific mycobacterial culture.

Discussion–conclusion

Tuberculosis vaccine is an effective intravesical immunotherapy for superficial urothelial bladder carcinoma. Most patients experience irritative voiding. Flu-like symptoms may occur and are resolved with symptomatic treatment. Osteoarticular complications are rare. Only 8 cases of prosthetic infections due to Mycobacterium bovis are reported. There is no predictive factor that could help identify patients at risk for developing BCG infection. Most of patients present sub-acute or chronic joint pain, with a great difficulty and a long delay for clinicians to make the diagnosis. In our case, the pseudo-tumoral aspect associated with the loosening of the THA showed many similarities with polyethylene wear induced osteolysis with a classic inflammatory granuloma. A regimen of antituberculous drugs was essential alongside with the removal of the mass.

Peri-prosthetic infection due to Mycobacterium bovis is a very rare complication of BCG therapy but clinicians should be able to evocate this diagnosis.