Comparing Synthetic Bone Alone Versus Synthetic Bone With Bone Marrow in Bone Lesions

Bone graft obtained from a patient's own bone (autogenous), usually around the pelvis, is currently considered the gold standard for bone grafting material. It provides a structural scaffold on which the patient's own bone may grow into (osteoconduction), growth factors that can stimulate healing (osteoinduction), and primitive cells (progenitors) that can stimulate bone formation directly (osteogenesis). It readily regains a blood supply from the surrounding tissues (revascularization) and is incorporated into the recipient site. However, there are significant disadvantages in the use of the patient's own bone graft including complications where the bone is taken from (donor site morbidity), limited availability and expense. For defects created by scraping (curettage) of non-cancerous (benign) bone lesions, a structural scaffold (osteoconduction) is generally considered the minimal necessary role that the graft material must serve to allow healing of the defect. Hence, human donor bone procured at the time of death (allografts) and synthetic bone fillers have been used as an alternative to the patient's own bone (autogenous bone graft).

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:

1. presence of graft within the soft tissues,
2. presence of a rim of radiolucency surrounding the grafted defect,
3. size/circumference of the rim of radiolucency,
4. resorption of graft material,
5. trabeculation through the defect and
6. persistence of graft material in the lesion.

Kappa statistics have shown good agreement for these parameters in our retrospective preliminary analysis of results for the TCP use without bone marrow over the first 2 years of its use by the PI.