Fiber Anchor Improves Pedicle Screw Fixation

An innovative demineralized bone fiber (DBF) anchor provides immediate improvement in screw fixation in both primary and revision cases.

The TheraCell (Los Angeles, CA, USA) TheraFuze DBF Anchor is a fiber matrix sleeve for screw augmentation made from DBF with osteoinductive potential. The DBF strands are molded into a proprietary tapered shape with depression at top for screw insertion, similar to a drywall anchor. It enhances immediate fixation strength of screws in compromised bone or revisions, and also stimulates bone formation for long term fixation. Testing has demonstrated it more than doubles the pullout force, compared to screws without the fiber anchor.

TheraFuze DBF Fiber Anchors are sized for use with 5.5-6.0mm, 6.5-7.0mm, 7.5-8.0mm and 8.5-9.0mm screws. In addition, the DBF can also be shaped into a fiber wrap formed into a one mm thick sheet. The lyophilized sheet may be rehydrated with saline, autologous blood, or bone marrow aspirate, creating a flexible sheet that can be rolled up for graft containment and maintains integrity when hydrated. A third option is FiberForm+, a moldable demineralized putty that also includes mineralized cortical chips to provide additional compression resistance and radiodensity for visualization.

“The TheraFuze DBF Fiber Anchor offers a cost-effective solution for revision cases or where the surgeon ‘feels’ the bone quality is compromised, as it provides significant improved initial in vivo fixation,” said Curt Cooper, chief business development officer at TheraCell. “The Fiber Anchor demonstrated that it promotes new bone formation in apposition to the screw with interdigitation of remodeled bone into the threads surrounded by native bone.”

“I was extremely interested to use the Fiber Anchor because of the tremendous potential for improved fixation at the proximal and distal ends of the construct; the improved fixation was tactilely obvious on screw insertion,” said Professor Neel Anand, MD, of Cedars Sinai Medical Center (Los Angeles, CA, USA). “I also was impressed with the Fiber Wrap. We rolled pieces of Fiber Wrap with some autologous bone graft and TheraFuze DBF containing mineralized cortical chips to make four ‘Burritos’. It made graft placement very easy and controlled.”

Pedicle screws provide a means of gripping a spinal segment. The screws themselves do not fixate the spinal segment, but act as firm anchor points that can then be connected with a rod. The screws are placed at two or three consecutive spine segments and then a short rod is used to connect the screws; this construct prevents motion at the segments that are being fused. After the bone graft grows, the screws and rods are no longer needed for stability and may be safely removed. However, most surgeons do not recommend removal unless the pedicle screws cause discomfort for the patient.

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