Evaluation of the Efficiency of the Bone Substitute Cerament-G Locally Delivering Gentamicin in the Treatment of Chronic Osteomyelitis of Long Bones

Inclusion Criteria: * Patient with suspected chronic osteomyelitis (stage III of the Cierny-Mader classification) of a long bone of the tibia, femur, humerus or forearm, at the diaphysis, metaphysis or epiphysis, defined as follows: * Supposed inoculation \> 3 months ; * At least one of the following clinical signs at the suspected infected site: * Spontaneous or supporting pain ; * Presence of fistula; or history of fistula discharge * Presence of serous or purulent flow; * Presence of bone exposure; * Local Inflammation; * Fever in the absence of any other explanation. * At least one of the following radiological signs at the suspected infected site: * Bone reshaping with osteolysis or periosteal apposition; * Presence of intramedullary abscess (if MRI performed); * Presence of a fistulous pathway to the intramedullary (if MRI performed); * Presence of bone sequestration visible on CT scan (if CT scan performed). * Patient in whom conventional surgical treatment of chronic osteomyelitis is possible, with decortication and corticotomy with endomedullary curettage (to eradicate bone sequestrums, reduce the inoculum, and identify the bacterium(s) involved) and secondary intramedullary residual cavity; * Patient in whom 3 months of systemic antibiotic therapy post-operatively are planned; * If osteosynthetic material is present in the infection site, this material should be considered preoperatively as completely removable during chronic osteomyelitis surgery; * Patient in whom a direct closure without tension is possible, or in whom a skin and soft-tissue/muscle flap can be performed within 15 days after the initial surgery; * Male or female patient between 18 and 80 years of age; * Patient who has given written informed consent to participate in the study; * Geographically stable patient; * Patient able to comply with follow-up visits, protocol schedule and therapeutic treatment, according to investigator's judgement; * Affiliated patient or beneficiary of a social security system Exclusion Criteria: * Acute hematogenic osteomyelitis (Cierny-Mader stage I) ; * Cortical osteitis (Cierny-Mader stage II); * Septic pseudoarthrosis (Cierny-Mader stage IV); * Patient requiring an estimated skin and soft-tissue/muscle flap that cannot be done within 15 days after surgery for the treatment of chronic osteomyelitis; * Woman who is pregnant, nursing or who is considering becoming pregnant during the study period; * Patient participating in another interventional study that could interfere with it; * Patient known to have hypersensitivity to aminoglycosides (especially gentamicin), sulfites (including calcium sulfate) or calcium hydroxyapatite; * Contraindication to the use of Cerament-G: severe myasthenia (class IV or higher according to the MGFA classification), , severe renal insufficiency (creatinine clearance \<30 mL/min according to the Cockcroft-Gault formula, or GFR \< 30 ml/min/1.73² according to the CKD-EPI or MDRDs equation or, dialysis patient), pre-existing disorders of calcium metabolism (total plasma calcium (or total corrected plasma calcium according to albuminemia) outside normal laboratory values); * Patient with endocrine or metabolic disorders known to affect osteogenesis (e.g., Paget's disease, renal osteodystrophy, hyperthyroidism, parathyroid disorder, Ehler-Danlos syndrome, osteogenesis imperfecta); * Patient with one or more untreated malignant cancers (including Marjolin's ulcer), or undergoing radiotherapy or chemotherapy; * Adult patient protected by law, under guardianship or trusteeship.