Characterization of craniomaxillofacial battle injuries sustained by United States service members in the current conflicts of Iraq and Afghanistan

Identification of temporal shifts of oral bacteria in bone regeneration following mandibular bone defect injury and therapeutic surgery in a porcine model

BACKGROUND

Considered the second largest and most diverse microbiome after the gut, the human oral ecosystem is complex with diverse and niche-specific microorganisms. Although evidence is growing for the importance of oral microbiome in supporting a healthy immune system and preventing local and systemic infections, the influence of craniomaxillofacial (CMF) trauma and routine reconstructive surgical treatments on community structure and function of oral resident microbes remains unknown. CMF injuries affect a large number of people, needing extensive rehabilitation with lasting morbidity and loss of human productivity. Treatment efficacy can be complicated by the overgrowth of opportunistic commensals or multidrug-resistant pathogens in the oral ecosystem due to weakened host immune function and reduced colonization resistance in a dysbiotic oral microbiome.

AIMS

To understand the dynamics of microbiota's community structure during CMF injury and subsequent treatments, we induced supra-alveolar mandibular defect in Hanford miniature swine (n = 3) and compared therapeutic approaches of immediate mandibullar reconstructive (IMR) versus delayed mandibullar reconstructive (DMR) surgeries.

METHODS

Using bacterial 16S ribosomal RNA gene marker sequencing, the composition and abundance of the bacterial community of the uninjured maxilla (control) and the injured left mandibula (lingual and buccal) treated by DMR were surveyed up to 70-day post-wounding. For the injured right mandibula receiving IMR treatment, the microbial composition and abundance were surveyed up to 14-day post-wounding. Moreover, we measured sera level of biochemical markers (e.g., osteocalcin) associated with bone regeneration and healing. Computed tomography was used to measure and compare mandibular bone characteristics such as trabecular thickness between sites receiving DMR and IMR therapeutic approaches until day 140, the end of study period.

RESULTS

Independent of IMR versus DMR therapy, we observed similar dysbiosis and shifts of the mucosal bacteria residents after CMF injury and/or following treatment. There was an enrichment of Fusobacterium, Porphyromonadaceae, and Bacteroidales accompanied by a decline in Pasteurellaceae, Moraxella, and Neisseria relative abundance in days allotted for healing. We also observed a decline in species richness and abundance driven by reduction in temporal instability and inter-animal heterogeneity on days 0 and 56, with day 0 corresponding to injury in DMR group and day 56 corresponding to delayed treatment for DMR or injury and immediate treatment for the IMR group. Analysis of bone healing features showed comparable bone-healing profiles for IMR vs. DMR therapeutic approach.

Reconstruction of functional human lips utilizing a prelaminated flap

Lips form a structure that are difficult to reconstruct after a traumatic avulsion injury or cancer ablative surgery secondary to loss of volumetric muscle mass. Traditional tissue engineering approaches of in vitro fabrication of mature tissue constructs can supply an alternative to the current surgical standard of care for functional lip reconstruction. We demonstrate a hybrid approach that combines the advantages of in situ muscle flap prefabrication with in vitro fabrication of an autogenous mucocutaneous construct as the laminate for prelamination to form a designer microvascular muscle free flap for lip reconstruction.

Acrylated Hyaluronic-Acid Based Hydrogel for the Treatment of Craniofacial Volumetric Muscle Loss

Current treatment options for craniofacial volumetric muscle loss (VML) have disadvantages and cannot fully restore normal function. Bio-inspired semisynthetic acrylated hyaluronic acid (AcHyA) hydrogel, which fills irregularly shaped defects, resembles an extracellular matrix, and induces a minimal inflammatory response, has shown promise in experimental studies of extremity VML. We therefore sought to study AcHyA hydrogel in the treatment of craniofacial VML. For this, we used a novel model of masseter VML in the rat. Following the creation of a 5 mm × 5 mm injury to the superficial masseter and administration of AcHyA to the wound, masseters were explanted between 2 and 16 weeks postoperatively and were analyzed for evidence of muscle regeneration including fibrosis, defect size, and fiber cross-sectional area (FCSA). At 8 and 16 weeks, masseters treated with AcHyA showed significantly less fibrosis than nonrepaired controls and a smaller decrease in defect size. The mean FCSA among fibers near the defect was significantly greater among hydrogel-repaired than control masseters at 8 weeks, 12 weeks, and 16 weeks. These results show that the hydrogel mitigates the fibrotic healing response and wound contracture. Our findings also suggest that hydrogel-based treatments have potential use as a treatment for the regeneration of craniofacial VML and demonstrate a system for evaluating subsequent iterations of materials in VML injuries.

Evaluating osteogenic effects associated with the incorporation of ascorbic acid in mineralized collagen scaffolds

Current treatments for craniomaxillofacial (CMF) defects motivate the design of instructive biomaterials that can promote osteogenic healing of complex bone defects. We report methods to promote in vitro osteogenesis of human mesenchymal stem cells (hMSCs) within a model mineralized collagen scaffold via the incorporation of ascorbic acid (vitamin C), a key factor in collagen biosynthesis and bone mineralization. An addition of 5 w/v% ascorbic acid into the base mineralized collagen scaffold significantly changes key morphology characteristics including porosity, macrostructure, and microstructure. This modification promotes hMSC metabolic activity, ALP activity, and hMSC-mediated deposition of calcium and phosphorous. Additionally, the incorporation of ascorbic acid influences osteogenic gene expression (BMP-2, RUNX2, COL1A2) and delays the expression of genes associated with osteoclast activity and bone resorption (OPN, CTSK), though it reduces the secretion of OPG. Together, these findings highlight ascorbic acid as a relevant component for mineralized collagen scaffold design to promote osteogenic differentiation and new bone formation for improved CMF outcomes.

Management of war-related facial wounds in Ukraine: the Lviv military hospital experience

The Lviv Military Medical Centre is the main hospital responsible for the management of wounded military personnel in Western Ukraine. Since the full-scale invasion of our country in 2022, we have had to rapidly adapt our department to managing a large influx of complex facial battle injuries. These wounds are generally from large explosive fragments such as from shells and commonly produce avulsive defects of the facial bones and overlying soft tissues. Using representative cases, we aim to discuss management of these extensive injuries and guide the future direction of our service, particularly in surgical training such as microvascular anastomosis.

An Analysis of Head and Neck Surgical Workload During Recent Combat Operations From 2002 to 2016

INTRODUCTION

In battle-injured U.S. service members, head and neck (H&N) injuries have been documented in 29% who were treated for wounds in deployed locations and 21% who were evacuated to a Role 4 MTF. The purpose of this study is to examine the H&N surgical workload at deployed U.S. military facilities in Iraq and Afghanistan in order to inform training, needed proficiency, and MTF manning.

MATERIALS AND METHODS

A retrospective analysis of the DoD Trauma Registry was performed for all Role 2 and Role 3 MTFs, from January 2002 to May 2016; 385 ICD-9 CM procedure codes were identified as H&N surgical procedures and were stratified into eight categories. For the purposes of this analysis, H&N procedures included dental, ophthalmologic, airway, ear, face, mandible maxilla, neck, and oral injuries. Traumatic brain injuries and vascular injuries to the neck were excluded.

RESULTS

A total of 15,620 H&N surgical procedures were identified at Role 2 and Role 3 MTFs. The majority of H&N surgical procedures (14,703, 94.14%) were reported at Role 3 facilities. Facial bone procedures were the most common subgroup across both roles of care (1,181, 75.03%). Tracheostomy accounted for 16.67% of all H&N surgical procedures followed by linear repair of laceration of eyelid or eyebrow (8.23%) and neck exploration (7.41%). H&N caseload was variable.

CONCLUSIONS

H&N procedures accounted for 8.25% of all surgical procedures performed at Role 2 and Role 3 MTFs; the majority of procedures were eye (40.54%) and airway (18.50%). These data can be used as planning tools to help determine the medical footprint and also to help inform training and sustainment requirements for deployed military general surgeons especially if future contingency operations are more constrained in terms of resources and personnel.

Evaluation of bacterial attachment on mineralized collagen scaffolds and addition of manuka honey to increase mesenchymal stem cell osteogenesis

The design of biomaterials to regenerate bone is likely to increasingly require modifications that reduce bacterial attachment and biofilm formation as infection during wound regeneration can significantly impede tissue repair and typically requires surgical intervention to restart the healing process. Further, much research on infection prevention in bone biomaterials has focused on modeling of non-resorbable metal alloy materials, whereas an expanding direction of bone regeneration has focused on development of bioresorbable materials. This represents a need for the prevention and understanding of infection in resorbable biomaterials. Here, we investigate the ability of a mineralized collagen biomaterial to natively resist infection and examine how the addition of manuka honey, previously identified as an antimicrobial agent, affects gram positive and negative bacterial colonization and mesenchymal stem cell osteogenesis and vasculature formation. We incorporate manuka honey into these scaffolds via either direct fabrication into the scaffold microarchitecture or via soaking the scaffold in a solution of manuka honey after fabrication. Direct incorporation results in a change in the surface characteristics and porosity of mineralized collagen scaffolds. Soaking scaffolds in honey concentrations higher than 10% had significant negative effects on mesenchymal stem cell metabolic activity. Soaking or incorporating 5% honey had no impact on endothelial cell tube formation. Although solutions of 5% honey reduced metabolic activity of mesenchymal stem cells, MSC-seeded scaffolds displayed increased calcium and phosphorous mineral formation, osteoprotegerin release, and alkaline phosphatase activity. Bacteria cultured on mineralized collagen scaffolds demonstrated surfaces covered in bacteria and no method of preventing infection, and using 10 times the minimal inhibitory concentration of antibiotics did not completely kill bacteria within the mineralized collagen scaffolds, indicating bioresorbable scaffold materials may act to shield bacteria from antibiotics. The addition of 5% manuka honey to scaffolds was not sufficient to prevent P. aeruginosa attachment or consistently reduce the activity of methicillin resistant staphylococcus aureus, and concentrations above 7% manuka honey are likely necessary to impact MRSA. Together, our results suggest bioresorbable scaffolds may create an environment conducive to bacterial growth, and potential trade-offs exist for the incorporation of low levels of honey in scaffolds to increase osteogenic potential of osteoprogenitors while high-levels of honey may be sufficient to reduce gram positive or negative bacteria activity but at the cost of reduced osteogenesis.

The current regenerative medicine approaches of craniofacial diseases: A narrative review

Craniofacial deformities (CFDs) develop following oncological resection, trauma, or congenital disorders. Trauma is one of the top five causes of death globally, with rates varying from country to country. They result in a non-healing composite tissue wound as they degenerate in soft or hard tissues. Approximately one-third of oral diseases are caused by gum disease. Due to the complexity of anatomical structures in the region and the variety of tissue-specific requirements, CFD treatments present many challenges. Many treatment methods for CFDs are available today, such as drugs, regenerative medicine (RM), surgery, and tissue engineering. Functional restoration of a tissue or an organ after trauma or other chronic diseases is the focus of this emerging field of science. The materials and methodologies used in craniofacial reconstruction have significantly improved in the last few years. A facial fracture requires bone preservation as much as possible, so tiny fragments are removed initially. It is possible to replace bone marrow stem cells with oral stem cells for CFDs due to their excellent potential for bone formation. This review article discusses regenerative approaches for different types of craniofacial diseases.

Craniomaxillofacial trauma in war-torn nations: Incidence, management gaps, and recommendations

Craniomaxillofacial trauma (CMFT) is a type of injury that affects the face, neck, and scalp, and includes facial bone fractures, dentoalveolar trauma, and soft tissue injuries. Work, traffic accidents, sports, and daily activities commonly cause these injuries. However, they are widespread in war-torn countries where armed conflict leads to a high incidence of CMFT. The lack of resources, health care infrastructure, and surgical personnel in these areas result in subpar treatment and poor patient outcomes, contributing to the high mortality and morbidity rates among war victims. The importance of a multidisciplinary approach to CMFT management cannot be overstated, but current obstacles, such as a lack of access to proper medical care and rehabilitation services, impede the development of effective treatments. CMFT treatment is complex and prohibitively expensive for war-torn nations to afford, necessitating international intervention to provide life-saving surgical procedures for those suffering from CMFT in conflict zones. Despite efforts to improve CMFT treatments in war-torn countries, more must be done to improve treatment outcomes. Data collection and research must also be improved in order to develop effective evidence-based treatment methods.

Biomedical applications of three-dimensional bioprinted craniofacial tissue engineering

Anatomical complications of the craniofacial regions often present considerable challenges to the surgical repair or replacement of the damaged tissues. Surgical repair has its own set of limitations, including scarcity of the donor tissues, immune rejection, use of immune suppressors followed by the surgery, and restriction in restoring the natural aesthetic appeal. Rapid advancement in the field of biomaterials, cell biology, and engineering has helped scientists to create cellularized skeletal muscle-like structures. However, the existing method still has limitations in building large, highly vascular tissue with clinical application. With the advance in the three-dimensional (3D) bioprinting technique, scientists and clinicians now can produce the functional implants of skeletal muscles and bones that are more patient-specific with the perfect match to the architecture of their craniofacial defects. Craniofacial tissue regeneration using 3D bioprinting can manage and eliminate the restrictions of the surgical transplant from the donor site. The concept of creating the new functional tissue, exactly mimicking the anatomical and physiological function of the damaged tissue, looks highly attractive. This is crucial to reduce the donor site morbidity and retain the esthetics. 3D bioprinting can integrate all three essential components of tissue engineering, that is, rehabilitation, reconstruction, and regeneration of the lost craniofacial tissues. Such integration essentially helps to develop the patient-specific treatment plans and damage site-driven creation of the functional implants for the craniofacial defects. This article is the bird's eye view on the latest development and application of 3D bioprinting in the regeneration of the skeletal muscle tissues and their application in restoring the functional abilities of the damaged craniofacial tissue. We also discussed current challenges in craniofacial bone vascularization and gave our view on the future direction, including establishing the interactions between tissue-engineered skeletal muscle and the peripheral nervous system.

The New Face of War: Craniofacial Injuries from Operation Inherent Resolve

INTRODUCTION

During the last 20 years of conflict in the Middle East, improvements in body armor and the use of improvised explosive devices has resulted in an increased incidence of complex craniofacial trauma (CFT). Currently, CFT comprises up to 40% of all casualties. We present new data from the recent conflict in Iraq and Syria during Operation Inherent Resolve.

METHODS

Data was collected for patients treated at Role 1, Role 2, and Role 3 facilities in Iraq and Syria over a one-year period. During this time, a specialized Head & Neck surgical augmentation team was deployed and co-located with the central Role 3 facility. Data included for this cross-sectional study: injury type and mechanism, triage category, initial managing facility and subsequent levels of care, and procedures performed.

RESULTS

Ninety-six patients sustained CFT over the study period. The most common injuries were soft tissue (57%), followed by cranial (44%) and orbital/facial (31%). Associated truncal and/or extremity injuries were seen in forty-six patients (48%). There were marked differences in incidence and pattern of injuries between mechanisms (Figure, all p < 0.05). While IEDs had the highest rate of cranial and truncal injuries, GSW and blunt mechanisms had higher incidences of orbital/facial and neck injuries. Overall, 45% required operative interventions including complex facial reconstruction, craniotomy, and open globe repair. Mortality was 6% with 83% due to associated severe brain injury. Most patients were local nationals (70%) who required discharge or transfer to the local healthcare system.

CONCLUSION

Complex craniofacial trauma is increasingly seen by deployed surgeons, regardless of subspecialty training or location. Deployment of a centrally located Head & Neck team greatly enhances the capabilities for forward deployed management of CFT, with excellent outcomes for both U.S. and local national patients.

LEVEL OF EVIDENCE

Level 4, retrospective study.

The Orthodontist's Role in Post-Battlefield Craniomaxillofacial Trauma Reconstruction

INTRODUCTION

In modern conflicts, deployed members are more vulnerable to craniomaxillofacial (CMF) injury than in previous conflicts. Patients presenting with CMF trauma are susceptible to post-trauma dental malocclusion and may require lengthy rehabilitation to achieve pre-injury function. This study surveyed military health care professionals who are potential contributors to CMF trauma rehabilitation teams to evaluate the orthodontist's inclusion in treating to the final outcome.

METHODS

Following approval from the Defense Health Agency Information Management Collections Office (Control Number: 9-DHA-1031-E) and the Air Force 59th Medical Wing Institutional Review Board (Reference Number: FWH20210061E), a survey study was conducted from April 2021 to July 2021. Volunteer participants were recruited from orthodontists, oral maxillofacial surgeons, medical specialists, and other dental specialists who have worked in military healthcare. Respondents reported their current practice treating CMF trauma, self-evaluated their knowledge of different aspects of the process, and submitted their perceptions on system and patient-limiting factors which affect outcomes. Descriptive statistics were conducted for ordinal data and chi-square tests for categorical data. Kruskal-Wallis analyses of variance compared cohorts with further Mann-Whitney U tests to distinguish the difference in cohorts.

RESULTS

Valid responses were collected from 171 participants. The responses were mostly from active duty military (93%) and well distributed among orthodontists, oral maxillofacial surgeons, other dental specialists, and medical specialists. When reporting current CMF trauma treatment practices, the majority of dental specialists stated they most commonly participate in a multidisciplinary team that addresses any CMF trauma case (68.4%) whereas medical specialists most commonly act as solo independent provider practice (53.6%). Dental specialists reported follow-up with post-trauma patients greater than 1 year and medical specialists reported the shortest post-trauma follow-up time with a median of 0 to 3 months. The majority of participants selected at least one system factor limiting CMF trauma care (78.7%) and at least one patient factor limiting CMF trauma care (86.3%). When asked about orthodontic participation in multidisciplinary teams, the responses showed a great range with orthodontists never included in CMF trauma care 23.1% of the time and always consulted regarding trauma cases 10.7% of the time. Other survey data collected allows the investigators to draw conclusions regarding specific limitations to treatment and recommendations for improvement, along with qualitative responses from survey participants.

CONCLUSIONS

Orthodontics, while available in the military, is underutilized in treating post-warfare or other CMF trauma. There are both system- and patient-limiting factors in the treatment of battlefield and non-battlefield CMF trauma. In addition, there are limitations to the inclusion of orthodontists in CMF trauma care which include the physical distance from primary treating specialists and the absence of standard referral protocols. Oral maxillofacial surgeons reported the highest understanding of the military orthodontist's contribution to a CMF trauma treatment team and medical specialists reported the lowest understanding. Advanced technology tools could help improve outcomes and multidisciplinary interactions. Further research is needed to study the complete CMF trauma rehabilitation process in military treatment facilities, evaluate the efficiency of cross-specialty referrals, and highlight best practices and protocols of functioning multidisciplinary teams.

Management of Maxillofacial Gunshot Injuries With Emphasis on Damage Control Surgery During the Yemen Civil War. Review of 173 Victims From a Level 1 Trauma Hospital in Najran, Kingdom of Saudi Arabia

Study Design

Studies on the concept of Damage Control Surgery (DCS) in the management of firearm injuries to the oral and maxillofacial region are still scarce, hence the basis for the current study.

Objectives

The objectives of the current study is to share our experience in the management of maxillofacial gunshot injuries with emphasis on DCS and early definitive surgery.

Methods

This was a retrospective study of combatant Yemeni patients with maxillofacial injuries who were transferred across the border from Yemen to Najran, Kingdom of Saudi Arabia. Demographics and etiology of injuries were stored. Paths of entry and exit of the projectiles were also noted. Also recorded were types of gunshot injury and treatment protocols adopted. Data was stored and analyzed using IBM SPSS Statistics for Windows Version 25 (Armonk, NY: IBM Corp).

Results

A total of 408 victims, all males, were seen during the study period with 173 (42.4%) males sustaining gunshot injuries to the maxillofacial region. Their ages ranged from 21 to 56 years with mean ± SD (27.5 ± 7.6) years. One hundred and twenty-one (70.0%) victims had extraoral bullet entry, while 53 (30.0%) victims had intraoral entry route. Ocular injuries, consisting of 25 (14.5%) cases of ruptured globe and 6 (3.5%) cases of corneal injuries, were the most commonly associated injuries. A total of 78 (45.1%) hemodynamically unstable victims had DCS as the adopted treatment protocol while early definitive surgery was carried out in 47(27.2%) hemodynamically stable victims. ORIF was the treatment modality used for the fractures in 132 (76.3%) of the victims.

Conclusions

We observed that 42.4% of the war victims sustained gunshot injuries. DCS with ORIF was the main treatment protocol adopted in the management of the hemodynamically unstable patients.

Real-Time Functional Assay of Volumetric Muscle Loss Injured Mouse Masseter Muscles via Nanomembrane Electronics

Skeletal muscle has a remarkable regeneration capacity to recover its structure and function after injury, except for the traumatic loss of critical muscle volume, called volumetric muscle loss (VML). Although many extremity VML models have been conducted, craniofacial VML has not been well-studied due to unavailable in vivo assay tools. Here, this paper reports a wireless, noninvasive nanomembrane system that integrates skin-wearable printed sensors and electronics for real-time, continuous monitoring of VML on craniofacial muscles. The craniofacial VML model, using biopsy punch-induced masseter muscle injury, shows impaired muscle regeneration. To measure the electrophysiology of small and round masseter muscles of active mice during mastication, a wearable nanomembrane system with stretchable graphene sensors that can be laminated to the skin over target muscles is utilized. The noninvasive system provides highly sensitive electromyogram detection on masseter muscles with or without VML injury. Furthermore, it is demonstrated that the wireless sensor can monitor the recovery after transplantation surgery for craniofacial VML. Overall, the presented study shows the enormous potential of the masseter muscle VML injury model and wearable assay tool for the mechanism study and the therapeutic development of craniofacial VML.

Glycosaminoglycan content of a mineralized collagen scaffold promotes mesenchymal stem cell secretion of factors to modulate angiogenesis and monocyte differentiation

Effective design of biomaterials to aid regenerative repair of craniomaxillofacial (CMF) bone defects requires approaches that modulate the complex interplay between exogenously added progenitor cells and cells in the wound microenvironment, such as osteoblasts, osteoclasts, endothelial cells, and immune cells. We are exploring the role of the glycosaminoglycan (GAG) content in a class of mineralized collagen scaffolds recently shown to promote osteogenesis and healing of craniofacial bone defects. We previously showed that incorporating chondroitin-6-sulfate or heparin improved mineral deposition by seeded human mesenchymal stem cells (hMSCs). Here, we examine the effect of varying scaffold GAG content on hMSC behavior, and their ability to modulate osteoclastogenesis, vasculogenesis, and the immune response. We report the role of hMSC-conditioned media produced in scaffolds containing chondroitin-6-sulfate (CS6), chondroitin-4-sulfate (CS4), or heparin (Heparin) GAGs on endothelial tube formation and monocyte differentiation. Notably, endogenous production by hMSCs within Heparin scaffolds most significantly inhibits osteoclastogenesis via secreted osteoprotegerin (OPG), while the secretome generated by CS6 scaffolds reduced pro-inflammatory immune response and increased endothelial tube formation. All conditioned media down-regulated many pro- and anti-inflammatory cytokines, such as IL6, IL-1β, and CCL18 and CCL17 respectively. Together, these findings demonstrate that modifying mineralized collagen scaffold GAG content can both directly (hMSC activity) and indirectly (production of secreted factors) influence overall osteogenic potential and mineral biosynthesis as well as angiogenic potential and monocyte differentiation towards osteoclastic and macrophage lineages. Scaffold GAG content is therefore a powerful stimulus to modulate reciprocal signaling between multiple cell populations within the bone healing microenvironment.

[Ballistic trauma of the face: A new scourge in Tunisia]

INTRODUCTION

Ballistic trauma of the face has aroused growing interest since the proliferation of conflicts in the world and particularly in the fight against terrorism. Their polymorphous and disfiguring character, their particular evolution and prognosis due to the ballistic aetiology, differentiate them from classic maxillofacial trauma. Tunisia did not escape this scourge after the revolution of 2011, and must therefore face the challenge of ballistic trauma in general and of the face in particular.

MATERIALS AND METHODS

We conducted a descriptive retrospective study on 30 patients who were victims of ballistic trauma of the face in the otolaryngology and maxillofacial surgery and ophthalmology departments of the Main Military Hospital of Tunis during the period from January 2011 to April 2018. Our objective was to assess the prevalence of these traumas in Tunisia after the revolution, and to assess their clinical and therapeutic aspects.

RESULTS

Our results showed a clear upward trend in these traumas, mainly caused by the opposition of our armed forces to the terrorist threat. The discussion of our results was therefore descriptive, comparing them to the literature.

CONCLUSION

Currently, it is imperative to develop a strategy for precise and effective management of ballistic trauma of the face due to the increase of armed conflicts, attacks and terrorist acts. Likewise, technological advances to develop soldier protection systems must be implemented.

Neck injuries - israel defense forces 20 years' experience

BACKGROUND

Neck injuries are an important cause of combat mortality and morbidity. This study's objective was to examine the characteristics and causes of neck injuries among Israel Defense Forces (IDF) and emphasize the best treatment protocols for the advanced life support providers in the prehospital combat environment.

METHODS

The IDF Trauma Registry (IDF-TR) includes prehospital data regarding casualties treated by the IDF's medical forces. This study was a retrospective, observational study that included all casualties who were injured between January 2006 and December 2018.

RESULTS

Between January 2016 and December 2018, 3294 casualties were recorded. During the study period, 1% (41/3,394) of all injury casualties in the registry were isolated neck injuries compared to 94% (3185/3,394) without neck injury. 42% (14/41) percent of the neck casualties were classified as urgent compared to 26% (830/3185, P = 0.09) in the no neck group. The most frequent type of injury mechanism in the neck casualties was penetrating injury (54% 22/41), mostly due to shrapnel (68% 15/22). 60% of neck injured personnel were injured during the 2nd Lebanon War and Operation Protective Edge in high-intensity conflicts. As for life-saving interventions, advanced airway interventions were performed in 12% of neck injured group (5/41) compared to 3% (104/3185, P = 0.02) in the no neck group. We revealed that cricothyroidotomy was performed in almost 10% (4/41) of neck injured casualties compared to only 1% (19/3185, P<0.0001) in no neck casualties. As for damage control resuscitation, neck injury casualties received higher amounts of Fresh Dried Plasma 7% (3/41) Vs. 1% (32/3185, P = 0.02) and Tranexamic acid 15% (6/41) Vs. 4% (124/3185, P = 0.01) compared to non-neck casualties.

CONCLUSIONS

Military neck injuries are a significant cause of substantial disability and result in incompatibility with combat duties in previously healthy soldiers. Prompt medical care, especially urgent hemodynamic and airway management, is paramount in these injuries. Routine use of designated neck protection might lower the number of neck injuries, mitigate their severity, and even decrease mortality.

LEVEL OF EVIDENCE

Level III (Retrospective study with up to two negative criteria).

Inclusion of a 3D-printed Hyperelastic Bone mesh improves mechanical and osteogenic performance of a mineralized collagen scaffold

Regenerative repair of craniomaxillofacial bone injuries is challenging due to both the large size and irregular shape of many defects. Mineralized collagen scaffolds have previously been shown to be a promising biomaterial implant to accelerate craniofacial bone regeneration in vivo. Here we describe inclusion of a 3D-printed polymer or ceramic-based mesh into a mineralized collagen scaffold to improve mechanical and biological activity. Mineralized collagen scaffolds were reinforced with 3D-printed Fluffy-PLG (ultraporous polylactide-co-glycolide co-polymer) or Hyperelastic Bone (90wt% calcium phosphate in PLG) meshes. We show degradation byproducts and acidic release from the printed structures have limited negative impact on the viability of mesenchymal stem cells. Further, inclusion of a mesh formed from Hyperelastic Bone generates a reinforced composite with significantly improved mechanical performance (elastic modulus, push-out strength). Composites formed from the mineralized collagen scaffold and either Hyperelastic Bone or Fluffy-PLG reinforcement both supported human bone-marrow derived mesenchymal stem cell osteogenesis and new bone formation. This was observed by increased mineral formation in Fluffy-PLG composites and increased cell viability and upregulation of RUNX2, Osterix, and COL1A2 genes in both composites. Strikingly, composites reinforced with Hyperelastic Bone mesh elicited significantly increased secretion of osteoprotegerin, a soluble glycoprotein and endogenous inhibitor of osteoclast activity. These results suggest that architectured meshes can be integrated into collagen scaffolds to boost mechanical performance and actively instruct cell processes that aid osteogenicity; specifically, secretion of a factor crucial to inhibiting osteoclast-mediated bone resorption. Future work will focus on further adapting the polymer mesh architecture to confer improved shape-fitting capacity as well as to investigate the role of polymer reinforcement on MSC-osteoclast interactions as a means to increase regenerative potential.

The impact of delayed surgical intervention following high velocity maxillofacial injuries

Our study compares the number of postoperative complications of Syrian patients admitted to the Galilee Medical Center (GMC) over a 5-year period (May 2013-May 2018) for treatment after initial high-velocity maxillofacial injuries sustained during the Syrian civil war. Specifically, we evaluated complication rates of patients arriving "early," within 24 h, to the GMC versus those who arrived "late," or 14-28 days following high-velocity maxillofacial injuries. Both groups of patients received definitive surgical treatment within 48 h of admission to our hospital with a total of 60 patients included in this study. The mean age was 26 ± 8 years (range: 9-50) and all except one were male. Postoperative complications in the early group were found to be significantly higher compared to the delayed arrival group (p = 0.006). We found that unintentionally delayed treatment may have contributed to a critical revascularization period resulting in improved healing and decreased postoperative morbidity and complications. We discuss potential mechanisms for complication rate variations, including critical vascularization periods. Our study may add to a growing body of work demonstrating the potential benefit of delayed surgical treatment for high-velocity maxillofacial injuries.

A tissue engineering approach for repairing craniofacial volumetric muscle loss in a sheep following a 2, 4, and 6-month recovery

Volumetric muscle loss (VML) is the loss of skeletal muscle that results in significant and persistent impairment of function. The unique characteristics of craniofacial muscle compared trunk and limb skeletal muscle, including differences in gene expression, satellite cell phenotype, and regenerative capacity, suggest that VML injuries may affect craniofacial muscle more severely. However, despite these notable differences, there are currently no animal models of craniofacial VML. In a previous sheep hindlimb VML study, we showed that our lab’s tissue engineered skeletal muscle units (SMUs) were able to restore muscle force production to a level that was statistically indistinguishable from the uninjured contralateral muscle. Thus, the goals of this study were to: 1) develop a model of craniofacial VML in a large animal model and 2) to evaluate the efficacy of our SMUs in repairing a 30% VML in the ovine zygomaticus major muscle. Overall, there was no significant difference in functional recovery between the SMU-treated group and the unrepaired control. Despite the use of the same injury and repair model used in our previous study, results showed differences in pathophysiology between craniofacial and hindlimb VML. Specifically, the craniofacial model was affected by concomitant denervation and ischemia injuries that were not exhibited in the hindlimb model. While clinically realistic, the additional ischemia and denervation likely created an injury that was too severe for our SMUs to repair. This study highlights the importance of balancing the use of a clinically realistic model while also maintaining control over variables related to the severity of the injury. These variables include the volume of muscle removed, the location of the VML injury, and the geometry of the injury, as these affect both the muscle’s ability to self-regenerate as well as the probability of success of the treatment.

Combat Facial Fractures Sustained During Operation Resolute Support and Operation Freedom’s Sentinel in Afghanistan

Introduction

Facial fractures sustained in combat are generally unrepresentative of those commonly experienced in civilian practice. In the US military, acute trauma patient care is guided by the Joint Trauma System Clinical Practice Guidelines but currently none exists for facial trauma.

Materials and methods

All casualties that underwent surgery to facial fractures between January 01, 2016 and September 15, 2019 at a US deployed Military Treatment Facility in Afghanistan were identified using the operating room database. Surgical operative records and outpatient records for local Afghan nationals returning for follow-up were reviewed to determine outcomes.

Results

55 casualties underwent treatment of facial fractures; these were predominantly from explosive devices (27/55, 49%). About 46/55 (84%) were local nationals, of which 32 (70%) were followed up. Length of follow-up ranged between 1 and 25 months. About 36/93 (39%) of all planned procedures developed complications, with the highest being from ORIF mandible (18/23, 78%). About 8/23 (35%) casualties undergoing ORIF mandible developed osteomyelitis, of which 5 developed nonunion. Complications were equally likely to occur in those procedures for “battlefield type” events such as explosive devices and gunshot wounds (31/68, 46%) as those from “civilian type” events such as falls or motor vehicle collisions (5/11, 45%).

Conclusions

Complications Rates from facial fractures were higher than that reported in civilian trauma. This likely reflects factors such as energy deposition, bacterial load, and time to treatment. Load sharing osteosynthesis should be the default modality for fracture fixation. External fixation should be considered in particular for complex high-energy or infected mandible fractures where follow-up is possible.

Use of Human Dental Pulp and Endothelial Cell Seeded Tyrosine-Derived Polycarbonate Scaffolds for Robust in vivo Alveolar Jaw Bone Regeneration

The ability to effectively repair craniomaxillofacial (CMF) bone defects in a fully functional and aesthetically pleasing manner is essential to maintain physical and psychological health. Current challenges for CMF repair therapies include the facts that craniofacial bones exhibit highly distinct properties as compared to axial and appendicular bones, including their unique sizes, shapes and contours, and mechanical properties that enable the ability to support teeth and withstand the strong forces of mastication. The study described here examined the ability for tyrosine-derived polycarbonate, E1001(1K)/β-TCP scaffolds seeded with human dental pulp stem cells (hDPSCs) and human umbilical vein endothelial cells (HUVECs) to repair critical sized alveolar bone defects in an in vivo rabbit mandible defect model. Human dental pulp stem cells are uniquely suited for use in CMF repair in that they are derived from the neural crest, which naturally contributes to CMF development. E1001(1k)/β-TCP scaffolds provide tunable mechanical and biodegradation properties, and are highly porous, consisting of interconnected macro- and micropores, to promote cell infiltration and attachment throughout the construct. Human dental pulp stem cells/HUVECs seeded and acellular E1001(1k)/β-TCP constructs were implanted for one and three months, harvested and analyzed by micro-computed tomography, then demineralized, processed and sectioned for histological and immunohistochemical analyses. Our results showed that hDPSC seeded E1001(1k)/β-TCP constructs to support the formation of osteodentin-like mineralized jawbone tissue closely resembling that of natural rabbit jaw bone. Although unseeded scaffolds supported limited alveolar bone regeneration, more robust and homogeneous bone formation was observed in hDPSC/HUVEC-seeded constructs, suggesting that hDPSCs/HUVECs contributed to enhanced bone formation. Importantly, bioengineered jaw bone recapitulated the characteristic morphology of natural rabbit jaw bone, was highly vascularized, and exhibited active remodeling by the presence of osteoblasts and osteoclasts on newly formed bone surfaces. In conclusion, these results demonstrate, for the first time, that E1001(1K)/ β-TCP scaffolds pre-seeded with human hDPSCs and HUVECs contributed to enhanced bone formation in an in vivo rabbit mandible defect repair model as compared to acellular E1001(1K)/β-TCP constructs. These studies demonstrate the utility of hDPSC/HUVEC-seeded E1001(1K)/β-TCP scaffolds as a potentially superior clinically relevant therapy to repair craniomaxillofacial bone defects.

Quantifying Vascular Changes Surrounding Bone Regeneration in a Porcine Mandibular Defect Using Computed Tomography

Angiogenesis is a critical process essential for optimal bone healing. Several in vitro and in vivo systems have been previously used to elucidate some of the mechanisms involved in the process of angiogenesis, and at the same time, to test potential therapeutic agents and bioactive factors that play important roles in neovascularization. Computed tomography (CT) is a noninvasive imaging technique that has recently allowed investigators to obtain a diverse range of high-resolution, three-dimensional characterization of structures, such as bone formation within bony defects. Unfortunately, to date, angiogenesis evaluation relies primarily on histology, or ex vivo imaging and few studies have utilized CT to qualitatively and quantitatively study the vascular response during bone repair. In the current study a clinical CT-based technique was used to evaluate the effects of rhBMP-2 eluting graft treatment on soft tissue vascular architecture surrounding a large segmental bone defect model in the minipig mandible. The objective of this study was to demonstrate the efficacy of contrast-enhanced, clinical 64-slice CT technology in extracting quantitative metrics of vascular architecture over a 12-week period. The results of this study show that the presence of rhBMP-2 had a positive effect on vessel volume from 4 to 12 weeks, which was explained by a concurrent increase in vessel number, which was also significantly higher at 4 weeks for the rhBMP-2 treatment. More importantly, analysis of vessel architecture showed no changes throughout the duration of the study, indicating therapeutic safety. This study validates CT analysis as a relevant imaging method for quantitative and qualitative analysis of morphological characteristics of vascular tissue around a bone healing site. Also important, the study shows that CT technology can be used in large animal models and potentially be translated into clinical models for the development of improved methods to evaluate tissue healing and vascular adaptation processes over the course of therapy. This methodology has demonstrated sensitivity to tracking spatial and temporal changes in vascularization and has the potential to be applied to studying changes in other high-contrast tissues as well. Impact Statement Tissue engineering solutions depend on the surrounding tissue response to support regeneration. The inflammatory environment and surrounding vascular supply are critical to determining if therapies will survive, engraftment occurs, and native physiology is restored. This study for the first time evaluates the blood vessel network changes in surrounding soft tissue to a bone defect site in a large animal model, using clinically available computed tomography tools and model changes in vessel number, size, and architecture. While this study focuses on rhBMP2 delivery impacting surrounding vasculature, this validated method can be extended to studying the vascular network changes in other tissues as well.

Tissue Engineered Axon Tracts Serve as Living Scaffolds to Accelerate Axonal Regeneration and Functional Recovery Following Peripheral Nerve Injury in Rats

Strategies to accelerate the rate of axon regeneration would improve functional recovery following peripheral nerve injury, in particular for cases involving segmental nerve defects. We are advancing tissue engineered nerve grafts (TENGs) comprised of long, aligned, centimeter-scale axon tracts developed by the controlled process of axon "stretch-growth" in custom mechanobioreactors. The current study used a rat sciatic nerve model to investigate the mechanisms of axon regeneration across nerve gaps bridged by TENGs as well as the extent of functional recovery compared to nerve guidance tubes (NGT) or autografts. We established that host axon growth occurred directly along TENG axons, which mimicked the action of "pioneer" axons during development by providing directed cues for accelerated outgrowth. Indeed, axon regeneration rates across TENGs were 3-4 fold faster than NGTs and equivalent to autografts. The infiltration of host Schwann cells - traditional drivers of peripheral axon regeneration - was also accelerated and progressed directly along TENG axons. Moreover, TENG repairs resulted in functional recovery levels equivalent to autografts, with both several-fold superior to NGTs. These findings demonstrate that engineered axon tracts serve as "living scaffolds" to guide host axon outgrowth by a new mechanism - which we term "axon-facilitated axon regeneration" - that leads to enhanced functional recovery.

Anisotropic mineralized collagen scaffolds accelerate osteogenic response in a glycosaminoglycan-dependent fashion

Regeneration of critically-sized craniofacial bone defects requires a template to promote cell activity and bone remodeling. However, induced regeneration becomes more challenging with increasing defect size. Methods of repair using allografts and autografts have inconsistent results, attributed to age-related regenerative capabilities of bone. We are developing a mineralized collagen scaffold to promote craniomaxillofacial bone regeneration as an alternative to repair. Here, we hypothesize modifying the pore anisotropy and glycosaminoglycan content of the scaffold will improve cell migration, viability, and subsequent bone formation. Using anisotropic and isotropic scaffold variants, we test the role of pore orientation on human mesenchymal stem cell (MSC) activity. We subsequently explore the role of glycosaminoglycan content, notably chondroitin-6-sulfate, chondroitin-4-sulfate, and heparin sulfate on mineralization. We find that while short term MSC migration and activity was not affected by pore orientation, increased bone mineral synthesis was observed in anisotropic scaffolds. Further, while scaffold glycosaminoglycan content did not impact cell viability, heparin sulfate and chondroitin-6-sulfate containing variants increased mineral formation at the late stage of in vitro culture, respectively. Overall, these findings show scaffold microstructural and proteoglycan modifications represent a powerful tool to improve MSC osteogenic activity.

Mineralized collagen scaffolds were modified to include anisotropic pore architecture and one of three glycosaminoglycans in order to improve bone mineral formation in vitro.

Sequential sequestrations increase the incorporation and retention of multiple growth factors in mineralized collagen scaffolds

Trauma induced injuries of the mouth, jaw, face, and related structures present unique clinical challenges due to their large size and complex geometry. Growth factor signaling coordinates the behavior of multiple cell types following an injury, and effective coordination of growth factor availability within a biomaterial can be critical for accelerating bone healing. Mineralized collagen scaffolds are a class of degradable biomaterial whose biophysical and compositional parameters can be adjusted to facilitate cell invasion and tissue remodeling. Here we describe the use of modified simulated body fluid treatments to enable sequential sequestration of bone morphogenic protein 2 and vascular endothelial growth factor into mineralized collagen scaffolds for bone repair. We report the capability of these scaffolds to sequester 60–90% of growth factor from solution without additional crosslinking treatments and show high levels of retention for individual (>94%) and multiple growth factors (>88%) that can be layered into the material via sequential sequestration steps. Sequentially sequestering growth factors allows prolonged release of growth factors in vitro (>94%) and suggests the potential to improve healing of large-scale bone injury models in vivo. Future work will utilize this sequestration method to induce cellular activities critical to bone healing such as vessel formation and cell migration.

Trauma induced injuries of the mouth, jaw, face, and related structures present unique clinical challenges due to their large size and complex geometry.

Facial injury management undertaken at US and UK medical treatment facilities during the Iraq and Afghanistan conflicts: a retrospective cohort study

OBJECTIVES

To perform the first direct comparison of the facial injuries sustained and treatment performed at USA and UK deployed medical treatment facilities (MTFs) in support of the military campaigns in Iraq and Afghanistan.

SETTING

The US and UK Joint Theatre Trauma Registries were scrutinised for all patients with facial injuries presenting alive to a UK or US deployed MTF between 1 March 2003 and 31 October 2011.

PARTICIPANTS

US and UK military personnel, local police, local military and civilians.

PRIMARY AND SECONDARY OUTCOME MEASURES

An adjusted multiple logistic regression model was performed using tracheostomy as the primary dependent outcome variable and treatment in a US MTF, US or UK military, mandible fracture and treatment of mandible fracture as independent secondary variables.

RESULTS

Facial injuries were identified in 16 944 casualties, with the most common being those to skin/muscle (64%), bone fractures (36%), inner/middle ear (28%) and intraoral damage (11%). Facial injuries were equally likely to undergo surgery in US MTF as UK MTF (OR: 1.06, 95% CI 0.4603 to 1.142, p=0.6656); however, variations were seen in injury type treated. In US MTF, 692/1452 (48%) of mandible fractures were treated by either open or closed reduction compared with 0/167 (0%) in UK MTF (χ²: 113.6; p≤0.0001). US military casualties who had treatment of their mandible fracture (open reduction and internal fixation or mandibulo-maxillary fixation) were less likely to have had a tracheostomy than those who did not undergo stabilisation of the fractured mandible (OR: 0.61, 95% CI 0.44 to 0.86; p=0.0066).

CONCLUSIONS

The capability to surgically treat mandible fractures by open or closed reduction should be considered as an integral component of deployed coalition surgical care in the future.

A Comparison of Ovine Facial and Limb Muscle as a Primary Cell Source for Engineered Skeletal Muscle

Volumetric muscle loss (VML) contributes to the number of soft tissue injuries that necessitate reconstructive surgery, but treatment options are often limited by tissue availability and donor site morbidity. To combat these issues, our laboratory has developed scaffold-free tissue-engineered skeletal muscle units (SMUs) as a novel treatment for VML injuries. Recently, we have begun experiments addressing VML in facial muscle, and the optimal starting cell population for engineered skeletal muscle tissue for this application may not be cells derived from hindlimb muscles due to reported heterogeneity of cell populations. Thus, the purpose of this study was to compare SMUs fabricated from both craniofacial and hindlimb sources to determine which cell source is best suited for the engineering of skeletal muscle. Herein, we assessed the development, structure, and function of SMUs derived from four muscle sources, including two hindlimb muscles (i.e., soleus and semimembranosus [SM]) and two craniofacial muscles (i.e., zygomaticus major and masseter). Overall, the zygomaticus major exhibited the least efficient digestion, and SMUs fabricated from this muscle exhibited the least aligned myosin heavy chain staining and consequently, the lowest average force production. Conversely, the SM muscle exhibited the most efficient digestion and the highest number of myotubes/mm²; however, the SM, masseter, and soleus groups were roughly equivalent in terms of force production and histological structure. Impact Statement An empirical comparison of the development, structure, and function of engineered skeletal muscle tissue fabricated from different muscles, including both craniofacial and hindlimb sources, will not only provide insight into innate regenerative mechanisms of skeletal muscle but also will give our team and other researchers the information necessary to determine which cell sources are best suited for the skeletal muscle tissue engineering.

The inclusion of zinc into mineralized collagen scaffolds for craniofacial bone repair applications

Implant osteoinduction and subsequent osteogenic activity are critical events that need improvement for regenerative healing of large craniofacial bone defects. Here we describe the augmentation of the mineral content of a class of mineralized collagen scaffolds under development for craniomaxillofacial bone regeneration via the inclusion of zinc ions to promote osteogenesis in vitro. Zinc is an essential trace element in skeletal tissue and bone, with soluble zinc being shown to promote osteogenic differentiation of porcine adipose derived stem cells. We report the development of a new class of zinc functionalized scaffolds fabricated by adding zinc sulfate to a mineralized collagen-glycosaminoglycan precursor suspension that was then freeze dried to form a porous biomaterial. We report analysis of zinc functionalized scaffolds via imaging (scanning electron microscopy), mechanical testing (compression), and compositional (X-ray diffraction, inductively coupled plasma mass spectrometry) analyses. Notably, zinc-functionalized scaffolds display morphological changes to the mineral phase and altered elastic modulus without substantially altering the composition of the brushite phase or removing the micro-scale pore morphology of the scaffold. These scaffolds also display zinc release kinetics on the order of days to weeks and promote successful growth and pro-osteogenic capacity of porcine adipose derived stem cells cultured within these zinc scaffolds. Taken together, we believe that zinc functionalized scaffolds provide a unique platform to explore strategies to improve in vivo osteogenesis in craniomaxillofacial bone injuries models. STATEMENT OF SIGNIFICANCE: Craniomaxillofacial bone defects that arise from traumatic, congenital, and post-oncologic origins cannot heal on their own and often require surgical intervention. We have developed a class of mineralized collagen scaffolds that promotes osteogenesis and bone regeneration. Here we describe the inclusion of zinc sulfate into the mineralized collagen scaffold to improve osteogenesis. Zinc functionalized scaffolds demonstrate altered crystallite microstructure but consistent Brushite chemistry, improved mechanics, and promote zinc transporter expression while supporting stem cell viability, osteogenic differentiation, and mineral biosynthesis.

Maxillofacial Fracture Patterns in Military Casualties

PURPOSE

Morbidity and death after facial trauma are substantial issues of concern both in civilians and in military personnel. This cross-sectional retrospective study sought to assess the prevalence, pattern, treatment, and complications of soft and hard tissue injuries of the face in military personnel from 2012 to 2018.

PATIENTS AND METHODS

This cross-sectional, retrospective, chart study analyzed the descriptive statistics of 591 patients by use of Microsoft Excel software (version 2013; Microsoft, Redmond, WA); we assessed military casualties treated at our hospital from 2012 to 2018. All military personnel were documented in our trauma registry. The patient records were studied, and information relating to patients' injuries was documented and assessed after compilation of patient data. This study was approved by our local institutional review board; the causes and complications of maxillofacial (MF) trauma were assessed. Statistical analysis was done. This study used descriptive statistics based on a total of 591 patients and Microsoft Excel software (version 2013).

RESULTS

Among maxillofacial (MF) fractures, midface fractures (49%) were most prevalent, followed by lower face fractures (43%) and upper face fractures (24%). The most common cause of injury was explosives (58%). The most frequent site of fracture in the mandible was the angle region, followed by the mandibular body and condyle. Nasal fractures were seen in 44% of midface fractures. The most commonly used technique for treatment was open reduction-internal fixation, which was used in 89% of patients.

CONCLUSIONS

The pattern of MF injuries and the treatment modalities used to treat these patients showed that the most frequent type of injury was midface fracture and most patients were treated by open reduction-internal fixation.

Reconstructing the Face of War

Introduction

Ongoing combat operations in Iraq, Afghanistan, and other theaters have led to an increase in high energy craniomaxillofacial (CMF) wounds. These challenging injuries are typically associated with complex tissue deficiencies, evolving areas of necrosis, and bony comminution with bone and ballistic fragment sequestrum. Restoring form and function in these combat-sustained CMF injuries is challenging, and frequently requires local and distant tissue transfers. War injuries are different than the isolated trauma seen in the civilian sector. Donor sites are limited on patients with blast injuries and they may have preferences or functional reasons for the decisions to choose flaps from the available donor sites.

Methods

A case series of patients who sustained severe combat-related CMF injury and were treated at Walter Reed National Military Medical Center (WRNMMC) is presented. Our study was exempt from Institutional Review Board review, and appropriate written consent was obtained from all patients included in the study for the use of representative clinical images.

Results

Four patients treated by the CMF team at Walter Reed National Military Medical Center are presented. In this study, we highlight their surgical management by the CMF team at WRNMMC, detail their postoperative course, and illustrate the outcomes achieved using representative patient clinical images. We also supplement this case series demonstrating military approaches to complex CMF injuries with CMF reconstructive algorithms utilized by the senior author (EDR) in the management of civilian complex avulsive injuries of the upper, mid, and lower face are thoroughly reviewed.

Conclusion

While the epidemiology and characteristics of military CMF injuries have been well described, their management remains poorly defined and creates an opportunity for reconstructive principles proven in the civilian sector to be applied in the care of severely wounded service members. The War on Terror marks the first time that microsurgery has been used extensively to reconstruct combat sustained wounds of the CMF region. Our manuscript reviews various options to reconstruct these devastating CMF injuries and emphasizes the need for steady communication between the civilian and military surgical communities to establish the best care for these complex patients.

Potential therapeutic use of relaxin in accelerating closure of cranial bone defects in mice

Bone fractures are associated with considerable morbidity and increased mortality. A major limitation to healing is lack of bone blood flow, which is impaired by physical disruption of intraskeletal and/or periosteal vasculature by the fracture. Thus, pharmacological interventions are needed to improve osseous blood flow, thereby accelerating bone fracture closure. Relaxin is secreted by the ovary and circulates in rodents and humans during pregnancy. Because relaxin might benefit bone fracture healing by stimulating angiogenesis, vasculogenesis (and potentially osteogenesis) through mobilization and activation of bone marrow progenitor cells, and by increasing blood flow via vasodilation, we investigated whether relaxin administration would accelerate closure of a calvarial defect in mice. Whether administered systemically by osmotic pump or locally by collagen scaffolds for ~2 week period after lesioning, relaxin did not accelerate bone healing. Despite implementing relaxin doses that reached plasma concentrations spanning the physiological to supraphysiological range, testing the closure of two different sizes of calvarial lesions, allowing for different intervals of time from instigation of cranial lesion to euthanasia, and investigating mice of different ages, we did not observe a significant benefit of relaxin in bone lesion healing. Nor did we observe stimulation of blood vessel formation in the bone lesion by the hormone. An incidental finding was that relaxin appeared to enhance trabecular bone growth in an uninjured control bone (femur). Although the results of this study were not supportive of a therapeutic benefit for relaxin on calvarial defect closure, future investigation is needed employing different animal species and experimental models of bone fracture.

Evaluation of some mechanical properties of a new silicone elastomer for maxillofacial prostheses after addition of intrinsic pigments

OBJECTIVE

The approximate life span of a silicone maxillofacial prosthesis is as short as 1.5-2 years of clinical service, then a new prosthesis should be fabricated. The most common reason for re-making the prosthesis is silicone mechanical properties degradation. The aim of this study was to assess some mechanical properties of VST-30 silicone for maxillofacial prostheses after addition of intrinsic pigments.

METHODS

Two types of intrinsic pigments (rayon flocking and burnt sienna); each of them was incorporated into silicone. One hundred and twenty samples were prepared and split into 4 groups according to the conducted tests (tear strength, hardness, surface roughness, and tensile strength and elongation percentage) with 30 samples for each test. Each group was equally split into three subgroups. Group (A) was without pigment (control group), group (B) was with rayon flocking and group (C) was with burnt sienna.

RESULTS

Samples with rayon flocking showed a highly significant decrease in hardness and there was a significant increase in tear strength, while there were non-significant differences in surface roughness, tensile strength and elongation percentage. Samples with burnt sienna showed a highly significant increase in tear strength and a highly significant decrease in hardness, but surface roughness, tensile strength and elongation percentage showed non-significant differences. However, there were non-significant differences between experimental groups in all tests.

CONCLUSIONS

The addition of each of rayon flocking and burnt sienna changed the mechanical properties of the VST-30 silicone, while no superior pigment-silicone combination was revealed in all the conducted tests.

Localized low-dose rhBMP-2 is effective at promoting bone regeneration in mandibular segmental defects

At least 26% of recent battlefield injuries are to the craniomaxillofacial (CMF) region. Recombinant human bone morphogenetic protein 2 (rhBMP-2) is used to treat CMF open fractures, but several complications have been associated with its use. This study tested the efficacy and safety of a lower (30% recommended) dose of rhBMP-2 to treat mandibular fractures. rhBMP-2 delivered via a polyurethane (PUR) and hydroxyapatite/β-tricalcium phosphate (Mastergraft®) scaffold was evaluated in a 2 cm segmental mandibular defect in minipigs. Bone regeneration was analyzed at 4, 8, and 12 weeks postsurgery using clinical computed tomography (CT) and rhBMP-2, and inflammatory marker concentrations were analyzed in serum and surgery-site drain effluent. CT scans revealed that pigs treated with PUR-Mastergraft® + rhBMP-2 had complete bone bridging, while the negative control group showed incomplete bone-bridging (n = 6). Volumetric analysis of regenerated bone showed that the PUR-Mastergraft® + rhBMP-2 treatment generated significantly more bone than control by 4 weeks, a trend that continued through 12 weeks. Variations in inflammatory analytes were detected in drain effluent samples and saliva but not in serum, suggesting a localized healing response. Importantly, the rhBMP-2 group did not exhibit an excessive increase in inflammatory analytes compared to control. Treatment with low-dose rhBMP-2 increases bone regeneration capacity in pigs with mandibular continuity defects and restores bone quality. Negative complications from rhBMP-2, such as excessive inflammatory analyte levels, were not observed. Together, these results suggest that treatment with low-dose rhBMP-2 is efficacious and may improve safety when treating CMF open fractures. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1491-1503, 2019.

Management of High-energy Avulsive Ballistic Facial Injury: A Review of the Literature and Algorithmic Approach

Background:

High-energy avulsive ballistic facial injuries pose one of the most significant reconstructive challenges. We conducted a systematic review of the literature to evaluate management trends and outcomes for the treatment of devastating ballistic facial trauma. Furthermore, we describe the senior author’s early and definitive staged reconstructive approach to these challenging patients.

Methods:

A Medline search was conducted to include studies that described timing of treatment, interventions, complications, and/or aesthetic outcomes.

Results:

Initial query revealed 41 articles, of which 17 articles met inclusion criteria. A single comparative study revealed that early versus delayed management resulted in a decreased incidence of soft-tissue contracture, required fewer total procedures, and resulted in shorter hospitalizations (level 3 evidence). Seven of the 9 studies (78%) that advocated delayed reconstruction were from the Middle East, whereas 5 of the 6 studies (83%) advocating immediate or early definitive reconstruction were from the United States. No study compared debridement timing directly in a head-to-head fashion, nor described flap selection based on defect characteristics.

Conclusions:

Existing literature suggests that early and aggressive intervention improves outcomes following avulsive ballistic injuries. Further comparative studies are needed; however, although evidence is limited, the senior author presents a 3-stage reconstructive algorithm advocating early and definitive reconstruction with aesthetic free tissue transfer in an attempt to optimize reconstructive outcomes of these complex injuries.

Craniofacial Tissue Engineering

The craniofacial complex is composed of fundamental components such as blood vessels and nerves, and also a variety of specialized tissues such as craniofacial bones, cartilages, muscles, ligaments, and the highly specialized and unique organs, the teeth. Together, these structures provide many functions including speech, mastication, and aesthetics of the craniofacial complex. Craniofacial defects not only influence the structure and function of the jaws and face, but may also result in deleterious psychosocial issues, emphasizing the need for rapid and effective, precise, and aesthetic reconstruction of craniofacial tissues. In a broad sense, craniofacial tissue reconstructions share many of the same issues as noncraniofacial tissue reconstructions. Therefore, many concepts and therapies for general tissue engineering can and have been used for craniofacial tissue regeneration. Still, repair of craniofacial defects presents unique challenges, mainly because of their complex and unique 3D geometry.

Three-dimensional printing for craniomaxillofacial regeneration

Craniomaxillofacial injuries produce complex wound environments involving various tissue types and treatment strategies. In a clinical setting, care is taken to properly irrigate and stabilize the injury, while grafts are molded in an attempt to maintain physiological functionality and cosmesis. This often requires multiple surgeries and grafts leading to added discomfort, pain and financial burden. Many of these injuries can lead to disfigurement and resultant loss of system function including mastication, respiration, and articulation, and these can lead to acute and long-term psychological impact on the patient. A main causality of these issues is the lack of an ability to spatially control pre-injury morphology while maintaining shape and function. With the advent of additive manufacturing (three-dimensional printing) and its use in conjunction with biomaterial regenerative strategies and stem cell research, there is an increased potential capacity to alleviate such limitations. This review focuses on the current capabilities of additive manufacturing platforms, completed research and potential for future uses in the treatment of craniomaxillofacial injuries, with an in-depth discussion of regeneration of the periodontal complex and teeth.

Management of High-Velocity Injuries of the Head and Neck

Trauma centers must prepare to manage high-velocity injuries resulting from a mass casualty incidents as global terrorism becomes a greater concern and an increasing risk. The most recent conflicts in Iraq and Afghanistan have significantly improved understanding of battlefield trauma and how to appropriately address these injures. This article applies combat surgery experience to civilian situations, outlines the physiology and kinetics of high-velocity injuries, and reviews applicable triage and management strategies.

The Joint Facial and Invasive Neck Trauma (J-FAINT) Project, Iraq and Afghanistan: 2011-2016

Objective

Define the number and type of facial and penetrating neck injuries sustained in combat operations in Iraq and Afghanistan from 2011 to 2016. Compare recent injury trends to prior years of modern conflict.

Study Design

Case series with chart review.

Setting

Tertiary care hospital.

Methods

The Joint Theater Trauma Registry (JTTR) was queried for facial and neck injuries from Iraq and Afghanistan from June 2011 to May 2016. Injury patterns, severity, and patient demographics were analyzed and compared to previously published data from combat operations during January 2003 to May 2011.

Results

A total of 5312 discrete facial and neck injuries among 922 service members were identified. There were 3842 soft tissue injuries (72.3%) of the head/neck and 1469 (27.7%) facial fractures. Soft tissue injuries of the face/cheek (31.4%) and neck/larynx/trachea (18.8%) were most common. The most common facial fractures were of the orbit (26.3%) and maxilla/zygoma (25.1%). Injuries per month were highest in 2011 to 2012 and steadily declined through 2016. The percentage of nonbattle injuries trended up over time, ranging from 14.7% to 65%. Concurrent facial/neck soft tissue trauma or fracture was associated with an overall mortality rate of 2.44%. Comparison of our data to that previously published revealed no statistical difference in concurrent mortality (3.5%-2.2%, P = .053); an increase in orbital fractures ( P < .005), facial nerve injury ( P < .0005), and ear/tympanic membrane perforations ( P < .0005); and a decrease in mandible fractures ( P < .005).

Conclusion

Penetrating neck and facial injuries remain common in modern warfare. Assessing injury characteristics and trends supports continued improvements in battlefield protection and identifies areas requiring further intervention.

Achieving Acetylcholine Receptor Clustering in Tissue-Engineered Skeletal Muscle Constructs In vitro through a Materials-Directed Agrin Delivery Approach

Volumetric muscle loss (VML) can result from trauma, infection, congenital anomalies, or surgery, and produce permanent functional and cosmetic deficits. There are no effective treatment options for VML injuries, and recent advances toward development of muscle constructs lack the ability to achieve innervation necessary for long-term function. We sought to develop a proof-of-concept biomaterial construct that could achieve acetylcholine receptor (AChR) clustering on muscle-derived cells (MDCs) in vitro. The approach consisted of the presentation of neural (Z+) agrin from the surface of microspheres embedded with a fibrin hydrogel to muscle cells (C2C12 cell line or primary rat MDCs). AChR clustering was spatially restricted to areas of cell (C2C12)-microsphere contact when the microspheres were delivered in suspension or when they were incorporated into a thin (2D) fibrin hydrogel. AChR clusters were observed from 16 to 72 h after treatment when Z+ agrin was adsorbed to the microspheres, and for greater than 120 h when agrin was covalently coupled to the microspheres. Little to no AChR clustering was observed when agrin-coated microspheres were delivered from specially designed 3D fibrin constructs. However, cyclic stretch in combination with agrin-presenting microspheres led to dramatic enhancement of AChR clustering in cells cultured on these 3D fibrin constructs, suggesting a synergistic effect between mechanical strain and agrin stimulation of AChR clustering in vitro. These studies highlight a strategy for maintaining a physiological phenotype characterized by motor endplates of muscle cells used in tissue engineering strategies for muscle regeneration. As such, these observations may provide an important first step toward improving function of tissue-engineered constructs for treatment of VML injuries.

Management of Battlefield Injuries to the Skull Base

High velocity skull base injuries on the battlefield are unique in comparison to most civilian sector trauma. With more than 43,000 United States military personnel injuries during Operations Iraqi Freedom (OIF) and Enduring Freedom (OEF), the most recent conflicts in Iraq and Afghanistan have significantly expanded the understanding of the physiology of modern battlefield trauma and how to appropriately address these injuries. The acute care principles of effective triage, airway management, and hemorrhage control in these injuries can be life saving and are reviewed here. Specific injury patterns and battlefield examples are reviewed as well, with a review of some of the lessons learned while providing care in a deployed setting. Utilization of the knowledge learned in Iraq and Afghanistan, which have improved casualty care of deployed service members, can be used both in future military conflicts and in civilian trauma care.

Estimating patient-specific and anatomically correct reference model for craniomaxillofacial deformity via sparse representation

PURPOSE

A significant number of patients suffer from craniomaxillofacial (CMF) deformity and require CMF surgery in the United States. The success of CMF surgery depends on not only the surgical techniques but also an accurate surgical planning. However, surgical planning for CMF surgery is challenging due to the absence of a patient-specific reference model. Currently, the outcome of the surgery is often subjective and highly dependent on surgeon's experience. In this paper, the authors present an automatic method to estimate an anatomically correct reference shape of jaws for orthognathic surgery, a common type of CMF surgery.

METHODS

To estimate a patient-specific jaw reference model, the authors use a data-driven method based on sparse shape composition. Given a dictionary of normal subjects, the authors first use the sparse representation to represent the midface of a patient by the midfaces of the normal subjects in the dictionary. Then, the derived sparse coefficients are used to reconstruct a patient-specific reference jaw shape.

RESULTS

The authors have validated the proposed method on both synthetic and real patient data. Experimental results show that the authors' method can effectively reconstruct the normal shape of jaw for patients.

CONCLUSIONS

The authors have presented a novel method to automatically estimate a patient-specific reference model for the patient suffering from CMF deformity.

Electrodiagnostic Evaluation of Individuals Implanted With Extracellular Matrix for the Treatment of Volumetric Muscle Injury: Case Series

BACKGROUND

Electrodiagnosis can reveal the nerve and muscle changes following surgical placement of an extracellular matrix (ECM) bioscaffold for treatment of volumetric muscle loss (VML).

OBJECTIVE

The purpose of this study was to characterize nerve conduction study (NCS) and electromyography (EMG) changes following ECM bioscaffold placement in individuals with VML. The ability of presurgical NCS and EMG to be used as a tool to help identify candidates who are likely to display improvements postsurgically also was explored.

DESIGN

A longitudinal case series design was used.

METHODS

The study was conducted at the McGowan Institute for Regenerative Medicine at the University of Pittsburgh. Eight individuals with a history of chronic VML participated. The intervention was surgical placement of an ECM bioscaffold at the site of VML. The strength of the affected region was measured using a handheld dynamometer, and electrophysiologic evaluation was conducted on the affected limb with standard method of NCS and EMG. All measurements were obtained the day before surgery and repeated 6 months after surgery.

RESULTS

Seven of the 8 participants had a preoperative electrodiagnosis of incomplete mononeuropathy within the site of VML. After ECM treatment, 5 of the 8 participants showed improvements in NCS amplitude or needle EMG parameters. The presence of electrical activity within the scaffold remodeling site was concomitant with clinical improvement in muscle strength.

LIMITATIONS

This study had a small sample size, and participants served as their own controls. The electromyographers and physical therapists performing the evaluation were not blinded.

CONCLUSIONS

Electrodiagnostic data provide objective evidence of physiological improvements in muscle function following ECM placement at sites of VML. Future studies are warranted to further investigate the potential of needle EMG as a predictor of successful outcomes following ECM treatment for VML.

Investigation of a pre-clinical mandibular bone notch defect model in miniature pigs: clinical computed tomography, micro-computed tomography, and histological evaluation

OBJECTIVES

To validate a critical-size mandibular bone defect model in miniature pigs.

MATERIALS AND METHODS

Bilateral notch defects were produced in the mandible of dentally mature miniature pigs. The right mandibular defect remained untreated while the left defect received an autograft. Bone healing was evaluated by computed tomography (CT) at 4 and 16 weeks, and by micro-CT and non-decalcified histology at 16 weeks.

RESULTS

In both the untreated and autograft treated groups, mineralized tissue volume was reduced significantly at 4 weeks post-surgery, but was comparable to the pre-surgery levels after 16 weeks. After 16 weeks, CT analysis indicated that significantly greater bone was regenerated in the autograft treated defect than in the untreated defect (P=0.013). Regardless of the treatment, the cortical bone was superior to the defect remodeled over 16 weeks to compensate for the notch defect.

CONCLUSION

The presence of considerable bone healing in both treated and untreated groups suggests that this model is inadequate as a critical-size defect. Despite healing and adaptation, the original bone geometry and quality of the pre-injured mandible was not obtained. On the other hand, this model is justified for evaluating accelerated healing and mitigating the bone remodeling response, which are both important considerations for dental implant restorations.

A rapid, flexible method for incorporating controlled antibiotic release into porous polymethylmethacrylate space maintainers for craniofacial reconstruction

Severe injuries in the craniofacial complex, resulting from trauma or pathology, present several challenges to functional and aesthetic reconstruction. The anatomy and position of the craniofacial region make it vulnerable to injury and subsequent local infection due to external bacteria as well as those from neighbouring structures like the sinuses, nasal passages, and mouth. Porous polymethylmethacrylate (PMMA) "space maintainers" have proven useful in staged craniofacial reconstruction by promoting healing of overlying soft tissue prior to reconstruction of craniofacial bones. We describe herein a method by which the porosity of a prefabricated porous PMMA space maintainer, generated by porogen leaching, can be loaded with a thermogelling copolymer-based drug delivery system. Porogen leaching, space maintainer prewetting, and thermogel loading all significantly affected the loading of a model antibiotic, colistin. Weeks-long release of antibiotic at clinically relevant levels was achieved with several formulations. In vitro assays confirmed that the released colistin maintained its antibiotic activity against several bacterial targets. Our results suggest that this method is a valuable tool in the development of novel therapeutic approaches for the treatment of severe complex, infected craniofacial injuries.

Maxillofacial and neck trauma: a damage control approach

Severe maxillofacial and neck trauma exposes patients to life threatening complications such as airway compromise and hemorrhagic shock. These conditions require rapid actions (diagnosis and management) and a strong interplay between surgeons and anesthesiologists. Effective airway management often makes the difference between life and death in severe maxillofacial and neck trauma and takes initial precedence over all other clinical considerations. Damage control strategies focus on physiological and biochemical stabilization prior to the comprehensive anatomical and functional repair of all injuries. Damage control surgery (DCS) can be defined as the rapid initial control of hemorrhage and contamination, temporary wound closure, resuscitation to normal physiology in the intensive care unit (ICU) and subsequent reexploration and definitive repair following restoration of normal physiology. Damage control resuscitation (DCR) consists mainly of hypotensive (permissive hypotension) and hemostatic (minimal use of crystalloid fluids and utilization of blood and blood products) resuscitation. Both strategies should be administered simultaneously in all of these patients.

Effects of epidermal growth factor-loaded mucoadhesive films on wounded oral tissue rafts

Current treatments for traumatic oral mucosal wounds include the gold standard of autologous tissue and alternative tissue-engineered grafts. While use of autografts has disadvantages of minimal availability of oral keratinized tissue, second surgery, and donor site discomfort, tissue-engineered grafts are limited by their unavailability as off-the-shelf products owing to their fabrication time of 4-8 weeks. Hence, the current work aimed to develop a potentially cost-effective, readily available device capable of enhancing native mucosal regeneration. Considering the key role of epidermal growth factor (EGF) in promoting mucosal wound regeneration and the advantages of mucoadhesive delivery systems, mucoadhesive films composed of polyvinylpyrrolidone and carboxymethylcellulose were developed to provide sustained release of EGF for a minimum of 6 h. Bioactivity of released EGF supernatants was then confirmed by its ability to promote proliferation of BALB/3T3 fibroblasts. Efficacy of the developed system was then investigated in vitro using buccal tissues (ORL 300-FT) as a potential replacement for small animal studies. Although the mucoadhesive films achieved their desired role of delivering bioactive EGF in a sustained manner, treatment with EGF, irrespective of its release from the films or solubilized in medium, caused a hyperparakeratotic response from in vitro tissues with distinguishable histological features including thickening of the spinous layer, intra- and intercellular edema, and pyknotic nuclei. These significant morphological changes were associated with no improvements in wound closure. These observations raise questions about the potential of using in vitro tissues as a wound healing model and substitute for small animal studies. The mucoadhesive delivery system developed, however, with its potential for sustained release of bioactive growth factors and small molecules, may be loaded with other desired compounds, with or without EGF, to accelerate the process of wound healing.