An Enhanced Bone Implant Material for Combat Casualties

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Ellen Gawalt, PhD

Duquesne University

During recent U.S. military conflicts including Operation Enduring Freedom, orthopedic injuries have accounted for the majority of combat injuries. New technologies, techniques, and products are needed to treat these injuries to cranial, maxillofacial, and/or musculoskeletal soft and hard tissues. Ideal treatments should provide off-the-shelf materials containing biological factors (e.g. hemostatic agents, analgesics, antibiotics, drugs, hormones, cells) and biodegradable scaffolds to stabilize, protect, minimize tissue damage, and promote tissue repair.

Gawalt’s team envisions the development of off-the-shelf calcium aluminate (CA) materials:

1. In kits containing hydratable CA, engineered with antimicrobial and bone-regeneration-enhancing activities for use as an easily castable/moldable bone implant material in combat support hospitals, and,
2. As a castable implant material for a variety of reconstructive orthopedic uses in military medical centers (e.g. implants for critical-sized fractures, hip and knee replacements).

The current "gold standard" for bone replacement is the autograft. The additional surgery required to harvest autograft bone from a seriously wounded soldier is not desirable. And for large bone wounds/fractures, available autograft or allograft (cadaver) bone may be insufficient in amount. Gawalt proposes to employ novel methods to engineer CA materials in which phase composition, micro-porosity, surface texture, and dissolution rate will be controlled to create a three-dimensional structure with defined and controlled macro-porosity and volume stability. Compared to current bone graft and implant materials, the process of forming shapes by the novel methods at our disposal is relatively easy, making it desirable in a combat support and rear echelon medical setting. The team also proposes to use the chemical functionality of CA to enhance the antimicrobial and osteoinductive properties of this promising material for combat injury applications to improve bone wound healing and reduce soldier down time.

The application of calcium aluminates to bone repair is a very good fit for stated needs of the Combat Casualty Care Research Program. In particular, the Combat Injury Stabilization program area has a focus on "Battlefield Treatment of Fractures" with a desire to develop bone replacement materials with antimicrobial activities. The development of calcium aluminates as bone implant materials as outlined in this research directly addresses this important goal.