Brucella infection in arthroplasties is a rare event. An unspecific clinical symptomatology is associated with unclear radiographic peri-prosthetic signs of bone halisteresis. Only a positive anamnesis, combined with an antibiogram of the joint liquid and a high serum antibody titre, can lead to a definitive diagnosis. We report a case of Brucella melitensis infection in a total knee arthroplasty implanted 2 years earlier. With the absence of radiological signs of prosthetic loosening and thanks to a systemic antibiotic combined therapy (rifampicin + doxycycline) extended for 8 weeks, we were able to solve the infection avoiding surgery.

Common peroneal nerve palsy is an infrequent pathology mostly related to endogenous or exogenous compression. The exogenous compression is frequently related to trauma: knee fractures or hematoma arisen after a direct blow. Fractures may cause a direct lesion of the nerve; hematoma causes a compression of the nerve at the fibular neck causing pain and functional loss. Lesions of the common peroneal nerve can also be related to total knee arthroplasty. The clinical evaluation is characterized by muscle weakness with or without sensory abnormality. The etiopathogeneses of the compression have to be confirmed by ultrasound or magnetic resonance imaging before the surgical treatment. The purpose of this article is to describe a case of common peroneal nerve palsy due to a posttraumatic hematoma after a sport-related injury. We evaluated this case with dynamic ultrasound with good visualization of the morphology of the lesion and of the compression.