Daniel J. Stinner

Negative Pressure Wound Therapy Reduces Pseudomonas Wound Contamination More Than Staphylococcus Aureus

Purpose: The purpose of this study is to determine if negative pressure wound therapy (NPWT) treatment results in fewer bacteria than wet-to-dry (WTD) dressings in a contaminated open fracture wound model. Methods: For Study 1, complex wounds were created on the proximal left leg of goats. The wounds were inoculated with Pseudomonas aeruginosa. The wounds were débrided and irrigated 6 hours after inoculation. The first group received WTD dressing changes twice daily; the second and third groups received NPWT using systems from two different companies. All three groups received repeat débridements every 48 hours for 6 days. Bacteria quantification was performed both immediately before and after each débridement. For Study 2, the only changes were that Staphylococcus aureus was used and only one NPWT group was included. Results: In Study 1, there were significantly fewer Pseudomonas in both NPWT groups at all imaging sessions after the initial débridement and irrigation. At the 6-day time point, the wounds in the NPWT groups were 43 ± 14% and 68 ± 6% of the baseline amount, respectively. The WTD groups were 464 ± 102% of the baseline amount. In Study 2, NPWT did not reduce the S. aureus contamination within the wound. At the 6-day time point, the wounds in the NPWT and WTD groups contained 115 ± 19% and 192 ± 52% of the baseline values, respectively. Conclusion: NPWT showed a significant and sustained decrease in the Pseudomonas levels compared with WTD dressings at all time points. This beneficial effect was seen not seen in S. aureus.

Return to Duty Rate of Amputee Soldiers in the Current Conflicts in Afghanistan and Iraq

BACKGROUND The purpose of this study was to determine the percentage of amputee soldiers who sustained their injury during the current conflicts in Afghanistan and Iraq and have returned to duty. In addition, the authors plan to identify the factors that influence the amputees likelihood to return to duty. METHODS The computerized records of amputee soldiers who presented to the Physical Evaluation Board between October 1, 2001 and June 1, 2006 were reviewed. This data were crossreferenced with the Military Amputee Database. The following variables were extracted: age, gender, pay grade, amputation level, and final disposition. RESULTS During the period reviewed, there were 395 major limb amputees that met inclusion criteria. Of those, 65 returned to active duty (16.5%). The average age of amputees returning to duty was more than 4 years older than those who separated from the service (31.4 vs. 27.2), p < 0.0001. Officers and senior enlisted personnel returned to duty at a higher rate (35.3% and 25.5%, respectively) when compared with junior enlisted personnel (7.0%), p < 0.0001. Those with multiple extremity amputations have the lowest return to duty rate at 3%, when compared with the overall return to duty rate for single extremity amputees (20%), p < 0.0001. CONCLUSION During the 1980s, 11 of 469 amputees returned to active duty (2.3%). The number of amputees returning to duty has increased significantly, from 2.3% to 16.5%, due to advancements in combat casualty care and the establishment of centralized amputee centers.

Infectious complications and soft tissue injury contribute to late amputation after severe lower extremity trauma.

BACKGROUND Although most combat-related amputations occur early for unsalvageable injuries, >15% occur late after reconstructive attempts. Predicting which patients will abandon limb salvage in favor of definitive amputation has not been explored. The purpose of this study was to identify factors contributing to late amputation for type III open tibia fractures sustained in combat. METHODS Operative databases were reviewed to identify all combat-related type III open diaphyseal tibia fractures from March 2003 to September 2007. Patients were categorized based on their definitive treatment: group I, limb salvage; group II, early amputation (<12 weeks postinjury); group III, late amputation (≥ 12 weeks postinjury). Injury, treatment, and complication data were extracted from medical records and compared across groups. RESULTS We identified 213 consecutive fractures, including 166 (77.9%) treated definitively with limb salvage, 36 (16.9%) with early amputation, and 11 (5.2%) with late amputation. There was no difference in fracture severity among the three groups. Before amputation, group III was more likely to use autograft and bone morphogenic protein (27.3%), compared with group I (4.8%) and group II (0%), and was more likely to undergo rotational flap coverage (45.5%), compared with group II (0%). Group III patients had the highest average number of revision surgeries and rate of deep soft tissue infection and were more likely to have osteomyelitis (54.5%) before amputation compared with group I (13.9%) and group II (16.7%). CONCLUSION Patients definitively managed with late amputation were more likely to have soft tissue injury requiring flap coverage and have their limb salvage course complicated by infection.

Bacterial Adherence to Suture Materials

BACKGROUND Wound infections may be problematic for physicians. Whether a practitioner is managing complex penetrating trauma or a skin biopsy, there may be a need for suture closure. Suture material is an operator dependent variable and while little objective data exist to guide the choice of suture, it may play a role in wound infection. This study evaluates bacterial adherence to commonly used suture materials with a bioluminescent in vitro model. METHODS In all, 11 strands of size 2-0 poliglecaprone suture (Monocryl; Ethicon, Inc, Somerville, New Jersey), polypropylene suture (Prolene; Ethicon, Inc), silk suture (Ethicon, Inc), polyglycolic acid suture (Vicryl; Ethicon, Inc), and antimicrobial polyglycolic acid suture treated with triclosan (VicrylPlus; Ethicon, Inc) were immersed in a broth of Staphylococcus aureus engineered to emit photons. After biofilm formation, the suture strands were irrigated and imaged with a photon-capturing camera system yielding a total photon count that correlates with residual bacteria. RESULTS The Vicryl suture had the highest counts and was statistically significant in bacterial adherence versus all other sutures. No other suture material was significantly different from any other. CONCLUSIONS This study gives data to guide the selection of suture materials. Absorbable braided suture should not be used in closure of contaminated wounds or wounds at risk for developing infection. The antibiotic impregnated absorbable braided suture was similar to the other suture types; however, it is at risk for reverting to the properties of its untreated counterpart over time. The bacterial adherence of suture materials should be taken into account by all practitioners when closing wounds or debriding infected wounds.

Microbiology and injury characteristics in severe open tibia fractures from combat.

BACKGROUND: Type III open tibia fractures are common combat injuries. The purpose of the study was to evaluate the effect of injury characteristics and surveillance cultures on outcomes in combat-related severe open tibia fractures. METHODS: We conducted a retrospective study of all combat-related open Gustilo and Anderson (G/A) type III diaphyseal tibia fractures treated at our centers between March 2003 and September 2007. RESULTS: One hundred ninety-two Operation Iraqi Freedom/Operation Enduring Freedom military personnel with 213 type III open tibial shaft fractures were identified. Fifty-seven extremities (27%) developed a deep infection and 47 extremities (22%) ultimately underwent amputation at an average follow-up of 24 months. Orthopedic Trauma Association type C fractures took significantly longer to achieve osseous union (p = 0.02). G/A type III B and III C fractures were more likely to undergo an amputation and took longer to achieve fracture union. Deep infection and osteomyelitis were significantly associated with amputation, revision operation, and prolonged time to union. Surveillance cultures were positive in 64% of extremities and 93% of these cultures isolated gram-negative species. In contrast, infecting organisms were predominantly gram-positive. CONCLUSIONS: Type III open tibia fractures from combat unite in 80.3% of cases at an average of 9.2 months. We recorded a 27% deep infection rate and a 22% amputation rate. The G/A type is associated with development of deep infection, need for amputation, and time to union. Positive surveillance cultures are associated with development of deep infection, osteomyelitis, and ultimate need for amputation. Surveillance cultures were not predictive of the infecting organism if a deep infection subsequently develops. LEVEL OF EVIDENCE: III.

Silver Dressings Augment the Ability of Negative Pressure Wound Therapy to Reduce Bacteria in a Contaminated Open Fracture Model

BACKGROUND Despite a lack of evidence supporting their use, silver dressings are often used with negative pressure wound therapy (NPWT). This study investigates the effectiveness of silver dressings to reduce bacteria in contaminated wounds when used with NPWT. METHODS Complex orthopedic wounds were created on the proximal left legs of anesthetized goats. The wounds were inoculated with either a strain of bioluminescent Pseudomonas aeruginosa or Staphylococcus aureus. These bacteria are genetically modified to emit photons, thereby allowing quantification of bacterial concentration with a photon-counting camera system. The wounds were debrided 6 hours after inoculation and were treated with silver impregnated gauze combined with NPWT. Repeat debridements were performed every 48 hours for 6 days. Imaging was performed pre- and postdebridement. These results were compared with standard NPWT controls that used dressings without silver. RESULTS There were fewer bacteria in the silver groups than the standard NPWT groups at 6 days. In the groups that were inoculated with P. aeruginosa, wounds in the silver group contained 21% ± 5% of baseline bacterial load compared with 43% ± 14% in the standard NPWT group. The addition of the silver dressings has a more pronounced effect on Staphylococcus. Wounds in the silver group contained 25% ± 8% of baseline bacterial load compared with 115% ± 19% in the standard NPWT group. CONCLUSIONS The use of silver dressings with NPWT is a fairly common practice with limited literature to support its use in contaminated wounds. This study demonstrates that the addition of a silver dressing to NPWT effectively reduces bacteria in contaminated wounds and is more beneficial on the gram-positive bacteria. These data support the use of silver dressings in contaminated wounds, particularly ones contaminated by S. aureus.

Prevalence of Late Amputations During the Current Conflicts in Afghanistan and Iraq

During the current conflicts, over 950 soldiers have sustained a combat-related amputation. The majority of these are acute, but an unknown number are performed months to years after the initial injury. The goal of this study is to determine the prevalence of late amputations in our combat wounded. Electronic medical records and radiographs of all soldiers who had a combat-related, lower extremity injury that resulted in amputation were reviewed to confirm demographic, injury, and amputation information. Time to amputation was defined as a late amputation when it occurred more than 12 weeks following the date of injury. There were 348 major limb amputees that met inclusion criteria. Fifty-three (15.2%) amputees had a late amputation (range = 12 wk-5.5 yr). While the majority of combat-related amputations occur acutely, more than 15% occur late. This study demonstrates that further research is needed to identify predictive factors and outcomes of the late amputation.

Local Antibiotic Delivery Using Tailorable Chitosan Sponges: The Future of Infection Control?

Objectives: Local antibiotic delivery is a viable and attractive option for preventing infection. Unfortunately, the current options are limited and often necessitate surgical removal. This study evaluates the ability of a biodegradable and biocompatible chitosan sponge to minimize infection by delivering local antibiotics within the wound. Methods: A complex musculoskeletal wound was created on the hindlimb of goats and contaminated with Pseudomonas aeruginosa (lux) or Staphylococcus aureus (lux) bacteria. These bacteria are genetically engineered to emit photons, allowing for quantification with a photon-counting camera system. The wounds were closed and similarly débrided and irrigated with 9 L normal saline using bulb-syringe irrigation 6 hours after inoculation. Goats were assigned to different treatment groups: a control group with no adjunctive treatment and an experimental group using a chitosan sponge loaded with either amikacin (for wounds contaminated with P. aeruginosa) or vancomycin (for wounds contaminated with S. aureus). The wounds were closed after the procedure and evaluated 48 hours after initial contamination. Serum levels of the antibiotics were also measured at 6, 12, 24, 36, and 42 hours after treatment was initiated. Results: The wounds treated with the antibiotic-loaded chitosan sponge had significantly less bacteria than the untreated wounds (P < 0.05). The highest serum levels were 6 hours after treatment but remained less than 15% of target serum levels for systemic treatment. At study end point, all sponges were between 60% and 100% degraded. Conclusions: The chitosan sponges are effective delivering the antibiotic and reducing the bacteria within the wounds.

Volumetric muscle loss: persistent functional deficits beyond frank loss of tissue.

Open fracture is a common occurrence in civilian and military populations. Though great strides have been made in limb salvage efforts, persistent muscle strength deficits can contribute to a diminished limb function after the bone has healed. Over the past decade, a growing effort to establish therapies directed at de novo muscle regeneration has produced several therapeutic approaches. As this effort progresses and as therapies reach clinical testing, many questions remain regarding the pathophysiology of the volumetric loss of skeletal muscle. The current study demonstrates, in a rat “open fracture” model, that the volumetric loss of skeletal muscle results in persistent functional deficits that are dependent on muscle length and joint angle. Moreover, the injured muscle has an increased stiffness during passive stretch and a reduced functional excursion. A case study of a patient with an open type III tibia fracture resulting in volumetric muscle loss in the anterior and posterior compartment is also presented. Eighteen months after injury and tibia healing, persistent functional deficits are apparent with many of the same qualities demonstrated in the animal model. Muscle architectural adaptations likely underlie the altered intrinsic functional characteristics of the remaining musculature. Published 2014. This article is a U.S. Government work and is in the public domain in the USA. J Orthop Res 33:40–46, 2015.

Use of negative-pressure wound therapy in orthopaedic trauma.

Abstract Negative‐pressure wound therapy (NPWT) has become an important adjunct to the management of traumatic wounds and surgical incisions related to musculoskeletal trauma. On the battlefield, this adjunct therapy allows early wound management and safe aeromedical evacuation. NPWT mechanisms of action include stabilization of the wound environment, reduction of wound edema, improvement of tissue perfusion, and stimulation of cells at the wound surface. NPWT stimulates granulation tissue and angiogenesis and may improve the likelihood of primary closure and reduce the need for free tissue transfer. In addition, NPWT reduces the bacterial bioburden of wounds contaminated with gram‐negative bacilli. However, an increased risk of colonization of gram‐positive cocci (eg, Staphylococcus aureus) exists. Although NPWT facilitates wound management, further research is required to determine conclusively whether this modality is superior to other management options. Ongoing research will continue to define the indications for and benefits of NPWT as well as establish the role of combination therapy, in which NPWT is used with instillation of antibiotic solutions, placement of antibiotic‐laden cement beads, or silver‐impregnated sponges.