Bone reconstruction in critical sized defect (CSD) remains a real challenge in orthopedic surgery in children and adults. The Masquelet technique is an innovative therapeutic technique, which offers a bone reconstruction in two steps, by the formation of an induced membrane (IM) around a polymethylmethacrylate (PMMA) spacer placed into the bone defect. After, PMMA removal, the cavity is filled with corticocancellous graft allowing bone healing. Up to date, all angiogenesis and osteogenic properties of IM remain unknown. The purpose of this study is to characterize angiogenesis and osteogenic properties of IM in children and adults.

Inclusion Criteria:

• All patients treated at CHU Amiens-Picardie for bone critical sized defect treated using the induced membrane reconstruction technique.
• patients from 9 months to 60 years old

Exclusion Criteria:

• Patients managed by another reconstruction technique for critical sized defect
• Patients under guardianship, curators or deprived of liberty.
• Pregnant and nursing women.
• Patients who refused to participate in the study and to sign informed consent.