Extremity Injury Treatment

The injuries to arms and legs following blast injuries, severe blunt or penetrating trauma, fractures and vascular injuries and severe civilian trauma often result in the loss of large regions of tissue in the middle portion of the limb, disrupting the healing and use of the hand or foot. Extremity injury is quite prevalent and accounts for as much as 79% of reported trauma cases from theater. As one can imagine this severe trauma produces highly complex injuries that damage the vasculature, bone, muscle, nerve and other soft tissues. The military need for therapeutic interventions is one driven by trauma repair rather than disease treatment.

Another secondary sequelea resultant from this trauma is compartment syndrome. It is often undiagnosed initially due to the multiple tissue types involved. The conditions under which Wounded Warriors are initially treated and prepared for transport can contribute to the probability of compartment syndrome. Once compartment syndrome is diagnosed, the only current treatment option is fasciotomy, where the pressure is released from the "compartment" by opening the surrounding tissue, which must be done within hours of onset to ensure effective treatment. This leaves an open wound which is susceptible to infection and added complications. As a result, it is imperative that new methods are developed for compartment syndrome detection and monitoring during triage of the critically wounded.

Despite many advances in reconstructive surgery, current methods to reconstruct these tissues are inadequate in many settings. Presently, when preservation, repair or regeneration of these "bridging" tissues cannot be reliably achieved, an amputation of the arm or lower leg below the injured area becomes the best and only option to our Wounded Warriors. The military population is also younger than the civilian repair population and therefore therapeutic strategies must demonstrate greater durability. Our efforts are dedicated to developing new regenerative medicine therapies for helping save and rebuild injured limbs.

Some of the basic therapeutic strategies addressed in saving the limb, also referred to as "limb salvage", focus on the preservation or restoration of:

• Bridging bone and connective tissue (i.e. cartilage, tendon, ligament) and supportive soft tissues (i.e. muscle) to reestablish stability and enable mobility along the entire limb
• Bridging vascular defects and restoring blood flow to regions compromised by trauma to enable limb recovery and support bone and soft tissue regeneration
• Bridging peripheral nerve gaps to afford both motor and sensory restoration and appropriate muscle reinervation which may improve downstream rehabilitation and stave off muscle atrophy
• Regenerating healthy “high quality” pigmented skin complete with sweat glands to cover the injured area and to provide a durable barrier to infection

The Extremity Injury Repair Program will focus on using new technologies in regenerative medicine and tissue engineering (i.e. the novel use of cells, scaffolds and biomaterials) to provide surgeons with advanced tools and new options for repair and regeneration of these critical bridging tissues. The goal is to allow victims of severe military or civilian trauma to be able to recover from their injuries more rapidly, more reliably and also retain their limb as they return to productive life.

References:

• Rasmussen, et al 2011