The question that remains is whether additional growth factors that can stimulate bone formation (osteoinductive property) and/or cells that form bone directly (osteogenic property) facilitate healing of these defects when added to a material other than the patient's own bone graft source. In our experience with the use of the synthetic bone graft substitute ultraporous beta-tricalcium phosphate (TCP) (Vitoss, Orthovita, Inc.) over the last 3 years, the graft material, when combined with local blood alone, has performed well clinically but has persisted for a year or longer radiographically in some cases. Prolonged persistence of the graft material may serve as a potential stress riser, although we did not observe any untoward late effects in our published work. Several authors have studied the effects of composite grafts formed from a combination of bone graft substitutes and the patient's own bone marrow in animal models with promising results. There are no studies in the current literature evaluating the effects of healing in composite ultraporous beta-tricalcium phosphate and bone marrow aspirate (BMA) in defects after scraping of benign tumors (cavitary defects) in humans. The purpose of this study is to prospectively examine healing of cavitary defects treated with TCP alone versus those treated with TCP combined with BMA. Our hypothesis is that both graft resorption and trabeculation (radiographic measures of incorporation of the synthetic material by the native bone) will be more advanced at each time point in those patients that receive BMA plus TCP compared to those that receive TCP alone. Patients with any type of benign bone lesion indicated for surgical curettage would be offered inclusion in the study and followed for a minimum of 2 years post-operatively. Bone marrow aspiration would be obtained by a needle inserted through the skin (percutaneous aspiration) from the large bone of the pelvis (iliac crest) using a standard bone marrow aspiration needle. Patients with infection, bone marrow disorders, or other conditions that preclude use of supplementary the patient's bone marrow as well as those who prefer to use their own bone graft material (autograft) or donated human bone graft (allograft) alone would be excluded. Each patient will undergo radiographic evaluation of the lesion at 6 weeks, 3 months, 6 months, 1 year, 18 months and 2 years post operatively. At one time point (1 year) a computerized tomogram (CT) of the grafted region will be obtained for each patient. Two qualified, blinded, independent reviewers will evaluate the radiographs and CT scans for six criteria: