During its March 2010 meeting, the AAOS Board of Directors approved a new technology overview (TO) on synthetic bone void fillers. Kristy L. Weber, MD, chair of the Council on Research, Quality Assessment, and Technology, presented the document, which was developed by a physician workgroup under the direction of the Guidelines & Technology Oversight Committee.

In keeping with the definition of a TO, the document does not make recommendations for or against the use of bone void fillers for patients. TOs are considered educational tools that encourage readers to consider the information presented and reach their own conclusions.

A focus on five questions
The TO on bone void fillers focused on the following five questions regarding four clinical indications. The questions address the use of synthetic bone void fillers alone, their possible use as graft extenders, and the use of allografts as a comparison because clinical results with allografts are perceived as much closer to autografts in these areas of the spine. The task force limited the scope to materials that had some degree of structural integrity to support loading in the indications of fracture, tumor reconstruction, and periprosthetic reconstruction. Thus, the TO does not include demineralized products.

• Do patients treated with synthetic bone void fillers (alone) as a graft material have different clinical results when compared to patients treated with iliac crest bone grafts (autografts but not local autografts) in a posterolateral spine fusion?
• Do patients treated with synthetic bone void fillers that are supplemented with autograft have different clinical results than patients treated with local autografts alone in a posterolateral spine fusion?
• Do patients with metaphyseal defects as a result of fractures have different clinical outcomes if they are treated with synthetic bone void filler, allograft, or autograft in the defect?
• Do patients with contained defects from tumor (or other benign bone cysts) have different clinical outcomes when treated with synthetic bone void filler, autograft, or allograft?
• Do patients with contained defects from periprosthetic bone loss have different clinical outcomes when treated with synthetic bone void filler, allograft, or autograft?

These questions were developed to try to bring out areas where there would be literature to review and would have clinical relevance. Unfortunately, the literature in general discussing synthetic bone void fillers in clinical applications was sparse.

Using bone void fillers in the spine
The first question focused on the use of bone void fillers alone in spinal fusion. The work group identified only two studies that met the inclusion criteria, and these were in different populations (adolescent scoliosis and adult spondylolisthesis).

Only one level II study was found comparing outcomes of adolescent idiopathic scoliosis patients treated with either iliac crest autograft or synthetic bone void filler. The synthetic bone void filler group was found to have fewer intraoperative complications, lower visual analog scale (VAS) pain scores at discharge, and no donor site pain.

Only one level IV study in adult patients with spondylolisthesis was identified. This study reported operating times and blood loss that were statistically significant in favor of synthetic bone void filler.

No studies were found that compared patients treated with synthetic bone void fillers supplemented with autograft to patients treated with local autografts alone in a posterolateral spine fusion.

Bone void fillers in fractures
The third question focused on whether patients with metaphyseal defects as a result of fractures have different clinical outcomes if they are treated with synthetic bone void filler, allograft, or autograft in the defect.

Three Level II studies that compared synthetic bone void filler to autogenous bone in patients with metaphyseal defects as a result of fractures met the inclusion criteria. No statistically significant difference was found between groups in any of the eight outcome measures.

Two studies reported donor site pain, a common complaint of patients undergoing autogenous iliac crest grafting. One study reported that no patients experienced donor site pain 6 and 12 months after surgery, and another reported that all patients had donor site pain at hospital discharge.

Of the 18 complications reported, a statistically significant difference was reported between groups in two complications—implant site infection and stitch abscess—both in favor of the autograft group. The literature searches did not identify any data that compare synthetic bone void fillers to allografts in treating fracture defects.

No peer-reviewed data could be identified that addressed the fourth and fifth questions—whether patients with contained defects from tumor (or other benign bone cysts) have different clinical outcomes when treated with synthetic bone void filler, autograft, or allograft and whether patients with contained defects from periprosthetic bone loss have different clinical outcomes when treated with synthetic bone void filler, allograft, or autograft.

The complete TO, including detailed evidence tables extracted during its development, is available at www.aaos.org/technologyoverviews

Evidence-Based Medicine Information

John S. Kirkpatrick, MD, chaired the physician workgroup on the technology overview on synthetic bone void fillers. Dr. Kirkpatrick reports no conflicts related to this topic and has completed the online disclosure.

Developing a technology overview
The physician workgroup on “Synthetic Bone Void Fillers: A Technology Overview” was chaired by John S. Kirkpatrick, MD, and included Charles N Cornell, MD; Bang H. Hoang, MD; Wellington Hsu, MD; J. Tracy Watson, MD; and William C. Watters III, MD, chair of the Guidelines & Technology Oversight Committee. The group was supported by Charles M. Turkelson, PhD, director of the AAOS department of research & scientific affairs, and Jan Wies, MPH, manager, clinical practice guidelines unit.

The TO on synthetic bone void fillers is not intended to convey an official position by the AAOS. Instead, the information is provided as a service to help members identify and evaluate the available published literature on this topic so that they can provide the best possible care to their patients.

The AAOS developed its first TO, on the gender-specific knee, in December 2007. AAOS is involved in the development of technology overviews because technology plays a central role in the practice of orthopaedic surgery. In addition, AAOS seeks to be a resource for those seeking unbiased information on newly developed surgical procedures, drugs, biologics, and orthopaedic devices. The TO was funded solely by the AAOS.