Diagnosis of osteitis/arthritis requires clinical, microbiological and radiological data. Good quality samples must be obtained before antibiotic therapy is introduced to identify causative microorganisms. New technical methods such as PCR can improve the diagnosis. X-ray radiograph is always performed when osteitis is suspected, even if the diagnosis can be difficult since abnormalities are present late in the course of the disease. MRI is the best method to establish the diagnosis of osteitis or arthritis. Scintigraphy can be an interesting investigation since it can be promptly performed even in patients with foreign material. New technical such as PET-Scan could be interesting to establish the diagnosis. Collaboration between clinicians, microbiologists and radiologists is essential to establish the diagnosis in order to target the appropriate treatment and to improve the prognosis.