Management of conflict injuries to the upper limb. Part 1: assessment and early surgical care.

Upper limb injuries are common in conflict zones. The functions of the upper limb are impossible to replicate with prosthetic replacement and wherever possible attempts should be made to preserve the limb with further secondary reconstruction aimed at restoration of function. Casualty assessment, haemorrhage control and resuscitation are simultaneously undertaken at the receiving medical facility. Primary surgical management involves decontamination and debridement, skeletal stabilization, restoration of vascularity, compartment fasciotomy where indicated and wound temporization with dressings. Operative findings and interventions should be documented and if evacuation of the casualty is possible, copies should be provided in the medical records to facilitate communication in the chain of care. Secondary procedures are required for further assessment and debridement prior to planning reconstruction and definitive fracture stabilization, nerve repair, wound cover or closure.

High velocity gunshot injuries to the extremities: management on and off the battlefield.

The gunshot wounds sustained on the battlefield caused by military ammunition can be different in nature to those usually encountered in the civilian setting. The main difference is that military ammunition has typically higher velocity with therefore greater kinetic energy and consequently potential to destroy tissue. The surgical priorities in the management of gunshot wounds are hemorrhage control, preventing infection, and reconstruction. The extent to which a gunshot wound needs to be surgically explored can be difficult to determine and depends on the likely amount of tissue destruction and the delay between wounding and initial surgical treatment. Factors associated with greater energy transfer, e.g., bullet fragmentation and bony fractures, are predictors of increased wound severity and therefore a requirement for more surgical exploration and likely debridement. Gunshot wounds should never be closed primarily; the full range of reconstruction from secondary intention to free tissue transfer may be required.

Translational research to improve the treatment of severe extremity injuries.

OBJECTIVES: Severe extremity injuries are the most significant injury sustained in combat wounds. Despite optimal clinical management, non-union and infection remain common complications. In a concerted effort to dovetail research efforts, there has been a collaboration between the UK and USA, with British military surgeons conducting translational studies under the auspices of the US Institute of Surgical Research. This paper describes 3 years of work. METHODS: A variety of studies were conducted using, and developing, a previously validated rat femur critical-sized defect model. Timing of surgical debridement and irrigation, different types of irrigants and different means of delivery of antibiotic and growth factors for infection control and to promote bone healing were investigated. RESULTS: Early debridement and irrigation were independently shown to reduce infection. Normal saline was the most optimal irrigant, superior to disinfectant solutions. A biodegradable gel demonstrated superior antibiotic delivery capabilities than standard polymethylmethacrylate beads. A polyurethane scaffold was shown to have the ability to deliver both antibiotics and growth factors. DISCUSSION: The importance of early transit times to Role 3 capabilities for definitive surgical care has been underlined. Novel and superior methods of antibiotic and growth factor delivery, compared with current clinical standards of care, have been shown. There is the potential for translation to clinical studies to promote infection control and bone healing in these devastating injuries.

The changing pattern of amputations.

INTRODUCTION: Conflict in the Middle East over the past 10 years has seen a change in warfare tactics from the use of ballistic missiles to blast weapons, which has resulted in a well-documented change in wounding patterns. Due to the severity of these injuries, there have been large numbers of amputations, both as life and limb saving procedures. The purpose of this paper is to retrospectively review all UK service personnel who have undergone limb amputation in the last 8 years of conflict and compare those from the early years with the more recent. METHODS: All UK service personnel scoring more than 1 on the extremity score of the Abbreviated Injury Score were identified from the UK Joint Theatre Trauma Registry and separated into two temporal cohorts (August 2003-February 2008 and August 2008-July 2010). Intheatre medical facility and Role 4 hospital notes from the Queen Elizabeth Hospital Birmingham were examined for details of mechanisms of injury, number of limbs injured, associated injuries, method of amputation, microbiology of contaminating organisms and outcome. RESULTS: There were significant differences in the nature of the amputations, the number of multiple amputations and soft tissue perineal wounds, as well as a significantly higher Injury Severity Score in the later time period. There were also significant differences in the surgical techniques, with more guillotine amputations in the early group, and mechanism of injury, with more blast injuries in the late group. CONCLUSIONS: This study has confirmed the clinical impression that there has been a significant change in the limb trauma from the Iraq conflict to Afghanistan. These injury patterns have significantly different logistic implications and this must be considered when planning the required medical assets in future conflicts.

Dual-purpose bone grafts improve healing and reduce infection.

OBJECTIVE: To determine if a dual-purpose bone graft can regenerate bone and reduce infection in highly contaminated bone critical size defects in rats. METHODS: Biodegradable polyurethane (PUR) scaffolds were loaded with recombinant human bone morphogenetic protein-2 (BMP-2) and vancomycin (Vanc). The release kinetics of the BMP-2 were tuned to take advantage of its mechanism of action (ie, an initial burst to recruit cells and sustained release to induce differentiation of the migrating cells). The Vanc release kinetics were designed to protect the graft from contamination until it is vascularized by having a burst for a week and remaining well over the minimum inhibitory concentration for Staphylococcus aureus for 2 months. The bone regeneration and infection reduction capability of these dual-purpose grafts (PUR+Vanc+BMP-2) were compared with collagen sponges loaded with BMP-2 (collagen+BMP-2) and PUR+BMP-2 in infected critical size rat femoral segmental defects. RESULTS: The dual-delivery approach resulted in substantially more new bone formation and a modest improvement in infection than PUR+BMP-2 and collagen+BMP-2 treatments. CONCLUSIONS: The PUR bone graft is injectable, provides a more sustained release of BMP-2 than the collagen sponge, and can release antibiotics for more than 8 weeks. Thus, the dual-delivery approach may improve patient outcomes of open fractures by protecting the osteoinductive graft from colonization until vascularization occurs. In addition, the more optimal release kinetics of BMP-2 may reduce nonunions and the amount of growth factor required.

Effect of various concentrations of antibiotics on osteogenic cell viability and activity.

Infection is a common complication of open fractures. Systemic antibiotics often cause adverse events before eradication of infected bone occurs. The local delivery of antibiotics and the use of implants that deliver both growth factors and antimicrobials are ways to circumvent systemic toxicity while decreasing infection and to reach extremely high levels required to treat bacterial biofilms. When choosing an antibiotic for a local delivery system, one should consider the effect that the antibiotic has on cell viability and osteogenic activity. To address this concern, osteoblasts were treated with 21 different antibiotics over 8 concentrations from 0 to 5000 µg/ml. Osteoblast deoxyribonucleic acid content and alkaline phosphatase activity (ALP) were measured to determine cell number and osteogenic activity, respectively. Antibiotics that caused the greatest decrement include rifampin, minocycline, doxycycline, nafcillin, penicillin, ciprofloxacin, colistin methanesulfonate, and gentamicin; their cell number and ALP were significantly less than control at drug concentrations ≤ 200 µg/ml. Conversely, amikacin, tobramycin, and vancomycin were the least cytotoxic and did not appreciably affect cell number and ALP until very high concentrations were used. This comprehensive evaluation of numerous antibiotics' effects on osteoblast viability and activity will enable clinicians and researchers to choose the optimal antibiotic for treatment of infection and maintenance of healthy host bone.

Improving bone formation in a rat femur segmental defect by controlling bone morphogenetic protein-2 release.

Nonunion is a common complication in open fractures and other severe bone injuries. Recombinant human bone morphogenetic protein-2 (rhBMP-2) delivered on a collagen sponge enhances healing of fractures. However, the burst release of rhBMP-2 necessitates supra-physiological doses of rhBMP-2 to achieve a robust osteogenic effect, which introduces risk of ectopic bone formation and severe inflammation and increases the cost. Although the concept that the ideal pharmacokinetics for rhBMP-2 includes both a burst and sustained release is generally accepted, investigations into the effects of the release kinetics on new bone formation are limited. In the present study, biodegradable polyurethane (PUR) and PUR/microsphere [PUR/poly(lactic-co-glycolic acid)] composite scaffolds with varying rhBMP-2 release kinetics were compared to the collagen sponge delivery system in a critical-sized rat segmental defect model. Microcomputed tomography analysis indicated that a burst followed by a sustained release of rhBMP-2 from the PUR scaffolds regenerated 50% more new bone than the collagen sponge loaded with rhBMP-2, whereas a sustained release without the burst did not form significantly more bone than the scaffold without rhBMP-2. This study demonstrated that the putative optimal release profile (i.e., burst followed by sustained release) for rhBMP-2 can be achieved using PUR scaffolds, and that this enhanced pharmacokinetics regenerated more bone than the clinically available standard of care in a critical-sized defect in rat femora.

Infectious complications of combat-related mangled extremity injuries in the British military.

BACKGROUND: During the wars in Iraq and Afghanistan, extremity injuries have predominated; however, no systematic review of field and stabilization care with subsequent infectious complications exists. This study evaluates the infectious complications and possible risk factors of British military casualties with mangled extremities, highlighting initial care and infections. METHODS: This is a retrospective cohort study of British military casualties in Iraq and Afghanistan between August 2003 and May 2008. Casualties with mangled extremities undergoing limb salvage were evaluated for management strategies at the time of injury through evacuation back to the United Kingdom and subsequent infections. RESULTS: There were 84 casualties with 85 extremities (20 infected and 65 uninfected). Infected extremities had more Gustilo Classification IIIb. There were no differences by Injury Severity Score, age, durations from injury to evacuation, or surgery, or arrival in England, use of clotting materials, or method of extremity stabilization between infected and uninfected extremity injuries. Tourniquet use in the field and fasciotomy were associated with infections. Antimicrobial coverage was associated with infections. Staphylococcus aureus were recovered later in casualties' clinical course in contrast to early recovery of Acinetobacter. On multivariate analysis, tourniquet in the field, antibiotics during evacuation and in the operating room, and fasciotomy were associated with infection as were certain bacteria, notably, Pseudomonas aeruginosa. CONCLUSION: Infections occurred in 24% of those with mangled extremities including 6% with osteomyelitis. Certain procedures, likely reflective of injury severity, were associated with infections along with certain bacteria, P. aeruginosa and possibly S. aureus. Continued clarification is required for antimicrobial coverage (penicillin-based regimens vs. additional anaerobic coverage) and certain surgical procedures to improve casualty care.

Comparison of development of heterotopic ossification in injured US and UK Armed Services personnel with combat-related amputations: preliminary findings and hypotheses regarding causality.

BACKGROUND: Recent reports have documented the rate of heterotopic ossification (HO) formation in the residual limbs of combat-related amputees from the US Armed Forces injured in Operations Iraqi and Enduring Freedom. Final amputation level within the zone of injury and blast as the mechanism of injury were identified as possible risk factors for the occurrence and grade of HO. There has been no previous description of HO in combat-related amputees from the UK service personnel. The purpose of this study was to examine potential differences in the prevalence of HO between UK and US Allied Forces, with particular attention to these risk factors, patient exposures, and any treatment differences between these two groups. METHODS: We reviewed the medical records and radiographs of 35 combat-related amputations from the UK and contrasted them with 213 previously reported amputations in US military personnel. We evaluated prevalence and severity of residual limb HO, Injury Severity Score (ISS), the mechanism and zone of injury, type and level of amputation, number of debridements, method of wound irrigation, presence of severe head injury and/or burns injury, use of topical negative pressure therapy and pulse lavage, number of days until wound closure, type of closure, and subsequent infections. All patients had a minimum of 2-month posthospital discharge radiographic follow-up. Comparisons were made using Fisher's exact, one-way analysis of variance, and chi2 analyses. RESULTS: There was no significant difference in either the overall prevalence of HO or the prevalence of moderate to severe HO in the two populations. Twenty of 35 (57.1%) limbs in the UK amputations developed HO compared with 134 of 213 (63%) in the US amputations (p > 0.05). The UK amputations had 12 cases (34.3%) of moderate to severe HO compared with 72 cases (33.8%) in the US amputations (p > 0.05). However, there was a significant difference in the number of UK amputations 0 of 20 (0%) versus the number of US amputations 25 of 134 (12%; p = 0.04), which required excision of symptomatic lesions. There was a significant association in the development of HO in UK personnel with the use of topical negative pressure treatment (p = 0.05) and increasing ISS scores (p = 0.04) and in the development of moderate to severe HO with increasing ISS (p = 0.006) and severe HI (p = 0.04). Unlike in the previous report, no significant association was found in UK personnel between any of the remaining hypothesized risk factors and either the presence or grade of HO. CONCLUSIONS: Although no difference was identified in the overall prevalence of HO, there are inconsistencies in the possible underlying causes of HO between the two cohorts. Further research is required in an ongoing effort to determine a causal relationship between treatment and subsequent HO formation.

Sustained release of vancomycin from polyurethane scaffolds inhibits infection of bone wounds in a rat femoral segmental defect model.

Infection is a common complication in open fractures that compromises the healing of bone and can result in loss of limb or life. Currently, the clinical standard of care for treating contaminated open fractures comprises a staged approach, wherein the wound is first treated with non-biodegradable antibiotic-laden poly(methyl methacrylate) (PMMA) beads to control the infection followed by bone grafting. Considering that tissue regeneration is associated with new blood vessel formation, which takes up to 6 weeks in segmental defects, a biodegradable bone graft with sustained release of an antibiotic is desired to prevent the implant from becoming infected, thus allowing the processes of both vascularization and new bone formation to occur unimpeded. In the present study, we utilized biodegradable porous polyurethane (PUR) scaffolds as the delivery vehicle for vancomycin. Hydrophobic vancomycin free base (V-FB) was obtained by precipitating the hydrophilic vancomycin hydrochloride (V-HCl) at pH 8. The decreased solubility of V-FB resulted in an extended vancomycin release profile in vitro, as evidenced by the fact that active vancomycin was released for up to 8 weeks at concentrations well above both the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). Using PUR prepared from lysine triisocyanate (LTI) (PUR(LTI)), the extended in vitro release profile observed for V-FB translated to improved infection control in vivo compared to V-HCl in a contaminated critical-sized fat femoral segmental defect. The performance of PUR(LTI)/V-FB was comparable to PMMA/V-HCl beads in vivo. However, compared with PMMA, PUR is a biodegradable system which does not require the extra surgical removal step in clinical use. These results suggest that PUR scaffolds incorporating V-FB could be a potential clinical therapy for treatment of infected bone defects.

Earlier debridement and antibiotic administration decrease infection.

Timing of debridement and local antibiotic administration on infection has not been clearly defined. A contaminated critical size rat femur defect model was used to determine if earlier debridement with local antibiotics decreased infection. Defects were inoculated with Staphylococcus aureus. At 2, 6, or 24 hours following contamination, defects were irrigated and debrided then directly closed or treated with antibiotic-impregnated PMMA beads and then closed. Two weeks later, defects were examined for evidence of infection. There was a significant increase in evidence of infection between 2 and 6 hours and a further increase between 6 and 24 hours with debridement alone as well as with debridement plus local antibiotics. Treatment with antibiotics resulted in significantly less evidence of infection at 2 and 6 hours compared to debridement alone. It was concluded that early debridement in combination with local delivery of antibiotics of contaminated defects may reduce infections.

Complications of extremity vascular injuries in conflict.

INTRODUCTION: The extremities remain the most common sites of wounding in conflict, are associated with a significant incidence of vascular trauma, and have a high complication rate (infection, secondary amputation, and graft thrombosis). AIM: The purpose of this study was to study the complication rate after extremity vascular injury. In particular, the aim was to analyze whether this was influenced by the presence or absence of a bony injury. METHODS: A prospectively maintained trauma registry was retrospectively reviewed for all UK military casualties with extremity injuries (Abbreviated Injury Score >1) December 8, 2003 to May 12, 2008. Demographics and the details of their vascular injuries, management, and outcome were documented using the trauma audit and medical notes. RESULTS: Thirty-four patients (34%)--37 limbs (30%)--had sustained a total of 38 vascular injuries. Twenty-eight limbs (22.6%) had an associated fracture, 9 (7.3%) did not. Twenty-nine limbs (23.4%) required immediate revascularization to preserve their limb: 16 limbs (13%) underwent an initial Damage Control procedure, and 13 limbs (10.5%) underwent Definitive Surgery. Overall, there were 25 limbs (20.2%) with complications. Twenty-two were in the 28 limbs with open fractures, 3 were in the 9 limbs without a fracture (p < 0.05). There was no significant difference in the complication rate with respect to upper versus lower limb and damage control versus definitive surgery. CONCLUSION: We have demonstrated that prognosis is worse after military vascular trauma if there is an associated fracture, probably due to higher energy transfer and greater tissue damage.

Predicting the need for early amputation in ballistic mangled extremity injuries.

BACKGROUND: Despite modern advances, amputation is still a commonly performed operation in war. It is often difficult to decide whether to amputate after high-energy trauma to the lower extremity. To help guide this assessment, scoring systems have been developed with amputation threshold values. These studies were all conducted on a civilian population, encompassing a wide range of ages and methods of injury. The evidence for their sensitivity and specificity is inconclusive. The aim of this study was to assess the validity of the mangled extremity severity score (MESS), the only verified score, in a population of UK military patients with ballistic mangled extremity injuries. METHODS: We identified from the prospectively kept Joint Theater Trauma Registry all patients who had sustained ballistic lower limb open fractures during the recent conflicts in Iraq and Afghanistan (May 2003-April 2008). Demographics were assessed using both the trauma audit and the hospital notes. Patients were retrospectively evaluated with the MESS system for lower extremity trauma. Those that required an amputation were compared with those that had successful limb salvage. RESULTS: Seventy-seven military patients with 86 limbs who had ballistic mangled extremity injuries were identified, 22 of whom required amputation. The MESS did not help to decide whether or not an amputation was appropriate and in particular, the age was not relevant. A skeletal score of 4, while being associated with a higher amputation rate, was not predictive of its need. Most amputations were performed when an ischemic limb was present, and the general condition of the casualty precluded the lengthy reconstruction required for salvage. CONCLUSIONS: The management of ballistic extremity injuries in military patients should be considered separate to that of civilians with high-energy trauma extremity injuries. The authors have identified important factors in the management, in particular the need for early amputation, of the military mangled extremity.