Ballistic Trauma

Combat and domestic improvised explosive devices (IEDs) deserve special consideration and mention as they result in additional trauma to the soft and hard tissues that extend far beyond that of typical ballistic patterns of permanent and temporary cavitation effects seen with handguns, shotguns, or even high-powered rifles. In addition to direct tissue damage from blast exposure, blast casualties experience a variety of differing mechanisms of injury to their bodies. Such injuries encompass both low- and high-velocity ballistic penetrating patterns while also inflicting components of burn, blunt, crush, and shockwave trauma concurrently.

The shockwave mechanism is especially critical in wounding patterns, as it often causes extreme shearing, stretch, and avulsive forces that result in much more extensive injury than that noted by the initial visual inspection of the blast victim. These forces rapidly and forcibly travel through soft tissue planes along the paths of major peripheral and central nerves, veins and arteries, while also contributing shear injury to muscles and tendons (Figs. 1A,B).

Often, the blast pressure waves force foreign particulates throughout the extremity, and in conjunction with the corresponding pressure waves, direct injury occurs to the vascular structures as well as perineurial, perivascular, paratenon, and periosteal tissues. This situation can make decontamination of embedded foreign materials difficult and potentially compromise upper extremity salvage efforts. Finally, these mechanisms of injury may impact not only a substantial portion of the involved upper extremity, but often also adversely affect other body surfaces or tissues that provide workhorse reconstructive flaps or tissues used in extremity salvage and coverage.22 23

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Fig. 1
(A) Example of the extreme shearing, stretch, and avulsive forces to the right upper extremity secondary to explosive ballistic injury.
(B) Same extremity after salvage via serial débridements, conversion of external fixation to internal rigid fixation, and coverage with latissimus dorsi muscle flap and skin grafting.

Further Lessons Learned: Advancements in Soft Tissue Coverage for Limb Salvage in Extensive High-Energy Ballistic Extremity Injuries

Given the changes in severity and challenges of the multiextremity-injured combat casualty care patient, high volumes of massive soft tissue and composite type injury patterns have been increasingly encountered. These increasingly challenging wounds have led to our military reconstruction teams to utilize what we have termed the “hybrid reconstructive ladder/elevator.” This paradigm shift has contributed to great advancements and improvements in primary and secondary extremity reconstruction by incorporating various regenerative medicine therapies with traditional reconstruction techniques.

Regenerative medicine therapies, namely extracellular matrices for dermal regenerate templates or scaffolds, urinary bladder matrices, and other techniques have been instrumental in improving the durability of our reconstructions and decreasing ulceration or erosion of active and heavily used extremities in our amputee and limb salvage populations. Spray skin technologies have been used with early promising results and will likely be able to be extended to the civilian sector eventually. Autologous adipose tissue grafting for addressing secondary soft tissue defects, scarring, and/or tethering of extracellular matrices (ECMs), dermal regenerate templates (DRTs), and skin grafts to underlying tendons, muscles, or osseous structures have also had an increasing role in our ballistic injury cohorts.

ECMs and DRTs are regenerative medicine approaches and are reconstructive materials that act as three-dimensional bioactive scaffolds, consisting of structural and functional proteins as well as may contain growth factors in certain instances. Bone-regeneration strategies for segmental osseous defects including bone transport, vascularized and/or non-vascularized bone grafting strategies, and mesenchymal stem cells in isolation or in conjunction with scaffolds and/or composite chimeric flaps with bone and soft tissue components have been increasingly applied in reconstructions for limb salvage. Peripheral nerve regeneration strategies with allograft and/or autologous nerve components have been utilized in early settings of reconstruction.

Prosthetic and residual limb interfaces as well as neuroma treatment strategies with novel techniques such as target muscle reinnervation and implantable nerve/muscle signaling and control systems for better residual limb or salvaged extremities have continued to develop. Finally, vascularized allotransplantation has also shown to be beneficial in specific extremity injuries. All of the above areas have had increasing roles as complementary therapies and treatment strategies to our traditional reconstruction approaches with yet more to come.

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