The purpose of this study is to assess the ability a injectable bi-phasic ceramic bone substitute to provide bone generation and bone remodeling in patients with benign bone tumors.

The aim of the study is to assess the usefulness of injectable bi-phasic ceramic bone substitute (CERAMENT™ |BONE VOID FILLER) in patients with benign bone tumors. The primary objectives is to:

1. Assess the ability of bi-phasic ceramic bone substitute to provide bone generation and bone remodeling in patients with benign bone tumors.
2. Assess the safety of bi-phasic ceramic bone substitute as measured by device complaint/Adverse Events monitoring and documentation of subsequent surgical procedure.
3. In the case of bone cysts assess the ability of bi-phasic ceramic bone substitute to transform into bone and possibly induce bone formation in regions of the cyst not filled with the product.

Benign bone tumors are often treated with intralesional curettage which creates a bone defect that can be filled with e.g. demineralized bone matrix, autologous bone, ceramic bone substitutes or polymethylmetacrylate cement.

Autograft has been considered the golden standard because it possesses all three of the essential elements required for an optimal bone graft, but is associated with morbidity at the donor site and is limited in supply. Allograft has been employed as a good alternative to autograft but the concern for potential disease transmission remains. Synthetic bone graft substitutes have been gaining popularity as viable alternatives for void and defect filling eliminating the concerns with autograft and allograft. These synthetic bone substitutes have invariably been based on calcium phosphate and/or calcium sulfate materials which are osteoconductive and facilitate bone remodeling, although side effects such as drainage and wound complications slow remodeling to bone or negligible bone generation have limited their use. Thus, new synthetic bone substitutes with described positive effects in vertebroplasty, osteotomy, and smaller trauma defects merit further investigation also in treatment of larger bone defects.

In a prospective series, patients with benign bone tumors were treated by minimal invasive intervention with a bi-phasic and injectable ceramic bone substitute (CERAMENT™ BONE VOID FILLER), composed of 60% weight synthetic calcium sulfate (CaS) and 40% weight hydroxyapatite (HA) powder was mixed with a water-soluble radio-contrast agent iohexol (180 mg/ml) to make the material radiopaque. The defects were treated by either mini-invasive surgery (solid tumors) or percutaneous injection (cysts) and followed clinically and radiologically for 12 months. CT scan was performed after 12 months to confirm bone remodeling of the bone substitute. All patients were allowed full weight bearing immediately after surgery.

Inclusion Criteria:

• Patients admitted to the hospital for surgical treatment of benign bone lesion requiring bone grafting.

Exclusion Criteria:

• Patient below 6 years of ageIrreversible coagulopathy or bleeding disorder. Note regarding reversible coagulopathies: Patients on coumarin or other anticoagulants may participate. Investigators should follow routine practices for perioperative discontinuation and re-initiation of anticoagulants;
• A pre-existing calcium metabolism disorder (e.g. hypercalcemia).