Use of negative pressure wound therapy in the management of infected abdominal wounds containing mesh: an analysis of outcomes

The purpose of this study was to examine the clinical outcomes of negative pressure wound therapy (NPWT) using reticulated open-cell foam (ROCF) in the adjunctive management of abdominal wounds with exposed and known infected synthetic mesh. A non randomised, retrospective review of medical records for 21 consecutive patients with infected abdominal wounds treated with NPWT was conducted. All abdominal wounds contained exposed synthetic mesh [composite, polypropylene (PP), or knitted polyglactin 910 (PG) mesh]. Demographic and bacteriological data, wound history, pre-NPWT and comparative post-NPWT, operative procedures and complications, hospital length of stay (LOS) and wound healing outcomes were all analysed. Primary endpoints measured were (1) hospital LOS prior to initiation of NPWT, (2) total time on NPWT, (3) hospital LOS from NPWT initiation to discharge and (4) wound closure status at discharge. A total of 21 patients with abdominal wounds with exposed, infected mesh were treated with NPWT. Aetiology of the wounds was ventral hernia repair (n = 11) and acute abdominal wall defect (n = 10). Prior to NPWT initiation, the mean hospital LOS for the composite, PP and PG meshes were 76 days (range: 21-171 days), 51 days (range: 32-62 days) and 19 days (range: 12-39 days), respectively. The mean hospital LOS following initiation of NPWT for wounds with exposed composite, PP and PG mesh were 28, 31 and 32 days, respectively. Eighteen of the 21 wounds (86%) reached full closure after a mean time of 26 days of NPWT and a mean hospital LOS of 30 days postinitiation of NPWT. Three wounds, all with composite mesh left in situ, did not reach full closure, although all exhibited decreased wound dimensions, granulating beds and decreased surface area exposure of mesh. During NPWT/ROCF, one hypoalbuminemic patient with exposed PP mesh developed an enterocutaneous fistula over a prior enterotomy site. This patient subsequently underwent total mesh extraction, takedown of the fistula and PP mesh replacement followed by reinstitution of NPWT and flap closure. In addition to appropriate systemic antibiotics and nutritional optimisation, the adjunctive use of NPWT resulted in successful closure of 86% of infected abdominal wounds with exposed prosthetic mesh. Patient hospital LOS (except those with PG mesh), operative procedures and readmissions were decreased during NPWT compared with treatment prior to NPWT. Future multi-site prospective, controlled studies would provide a strong evidence base from which treatment decisions could be made in the management of these challenging and costly cases.     

The association of wound factors and symptoms of fatigue and pain with wound healing in chronic venous leg ulcers

The purpose of this study was: (1) to characterise the association of wound area, wound exudate C-reactive protein (CRP), broad-spectrum matrix metalloprotease protein (MMPs), and symptoms of fatigue and pain in individuals with chronic venous leg ulcers (CVLUs) over time and (2) to identify factors associated with the wound healing trajectory in CVLUs. Seventy four participants with CVLU who received weekly sharp debridement were recruited from a wound care clinic during the 8-week study period. To examine associations among wound CRP, MMPs, pain, fatigue, and wound healing trajectory over time, we calculated Bayes factors (BF) based on a linear mixed model. The mean age of participants was 71.8 (SD = 9.8) and the mean wound area was 2278 mm² (SD = 7085 mm²) at baseline. Higher fatigue was strongly associated with higher MMPs (BF = 9, 95% HDI: [−.05, .43]), lower CRP (BF = 11, 95% HDI: [−.02, .002]), and large areas of wound (BF = 20, 95% HDI: [−.001, .01]). Higher CRP and MMPs activity in wound exudate and higher fatigue were associated with a larger wound area. To facilitate wound healing, clinicians need to utilise the multifactorial approach, which includes wound treatment and management of symptoms such as pain and fatigue, because of the molecular and psycho-behavioural factors involved in wound healing.     

Impact of negative pressure wound therapy on open diaphyseal tibial fractures: A prospective randomized trial

IntroductionOpen tibial fractures are associated with a high incidence of mainly osteomyelitis. Negative pressure wound therapy (NPWT) is a novel form of treatment that uses subatmospheric pressure to effect early wound healing.Objectives and study designTo determine the effect of NPWT on incidence of deep infections/osteomyelitis after open tibial fractures using a prospective randomized study design.Materials and methodsNinety-three open tibial fractures were randomized into two groups receiving NPWT and the second group undergoing periodic irrigation, cleaning and debridement respectively. The wounds were closed or covered on shrinkage in size and sufficient granulation. Evidence of infection was sought during the course of treatment and follow up. Also serial cultures were sent every time the wound was cleaned.Results and conclusionsPatients in the control group developed a total of 11 infections (22%) as opposed to only 2 (4.6%) in the NPWT group (p < 0.05). The relative risk was 5.5 (95% confidence interval) suggesting patients who received NPWT were 5.5 times less likely to develop infection. Twenty patients developed positive growth when samples were sent for culture with 3 (6.9%) in the NPWT group and 17 (34%) in the control group (p < 0.05). Only 5 patients (25%) went on the develop osteomyelitis, all being a part of the control group. Thus negative pressure wound therapy is indeed beneficial for preventing the incidence of both acute infections and osteomyelitis in open fractures. However a significant difference was not seen in the time required for the wound to be ready for delayed primary closure or coverage.     

Wound management with negative pressure wound therapy in postoperative infection after open reconstruction of chronic Achilles tendon rupture

IntroductionDeep infection after reconstruction of chronic Achilles tendon rupture is a major and intractable complication.Case reportWe report a case of late deep infection following a surgery for chronic Achilles tendon rupture, and its simple and successful treatment with negative pressure wound therapy (NPWT). Six months following the reconstruction of chronic Achilles tendon rupture, a deep infection developed and reconstructed part of the tendon ruptured again. After appropriate debridement.DiscussionThere is no definitive treatment strategy for postoperative infection following open Achilles tendon repair. NPWT was applied to the wound, to promote wound healing and healthy granulation. In our case, NPWT promoted the wound healing and the infected Achilles tendon with tendon loss formed a healthy bridge with granulation tissue spontaneously. The patient resumed her normal activities of daily living, without requiring tendon transfer surgery. NPWT seems to be a simple and successful candidate for this situation.ConclusionNPWT seems to be effective for the treatment of postoperative infection following Achilles tendon repair, even in cases of tendon loss.     

Negative pressure wound therapy versus gauze dressings in managing open fracture wound of lower limbs: A meta-analysis of randomized controlled trials

BackgroundThe superiority of negative pressure wound therapy (NPWT) to standard gauze dressings for managing open fractures of the lower limbs remains controversial. This study aimed to comprehensively compare their clinical efficacy through a meta-analysis using randomized controlled trials (RCTs) alone. We hypothesized that NPWT would be more superior against infections.MethodsA literature search was implemented in various databases, including PubMed, Web of Science, Medline, Clinicaltrial.gov, and Cochrane Library, etc, to screen eligible RCTs. All included RCTs were evaluated for risk of bias using the Cochrane Collaboration tool. In accordance with the heterogeneity assessment, a fixed-effect or random-effect model was chosen for the data analysis.ResultsTen RCTs, including 2780 patients, were eligible for the meta-analysis. We found that patients in the NPWT group showed a lower overall infection rate (MD=0.70, 95% CI: 0.54–0.90, P = 0.005), acute wound infection rate (MD = 0.35, 95% CI: 0.16–0.77, P = 0.009), and shorter hospital stay (MD = 24.00, 95% CI: 6.82–84.46, P < 0.00001) compared with the control group. The NPWT group showed a higher proportion of patients with wound coverage than the control group. No significant difference was found between the two groups in terms of function score and other complications, including deep infection rate, amputation, and bone nonunion.ConclusionsFrom the pooled results, we suggest that NPWT may be superior than traditional gauze dressings for managing open fractures of the lower limbs.     

Measurement of vancomycin hydrochloride concentration in the exudate from wounds receiving negative pressure wound therapy: a pilot study

It has been reported that negative pressure wound therapy (NPWT) is effective in the treatment of contaminated wounds. We hypothesised that systemically administered antibiotics migrate to wound site effectively by NPWT, which provides the antibacterial effect. We measured and compared the concentrations of vancomycin in the exudate and blood serum. Eight patients with skin ulcers or skin defect wounds who were treated with NPWT and were administered an intravenous drip of vancomycin were enrolled in this study. The wound surfaces were muscle, muscle fascia or adipose tissue. We administered vancomycin intravenously to NPWT patients (1–3 g/day). The exudate was obtained using 500 ml V.A.C. ATS^® canisters without gel. Three days later, the concentrations of vancomycin were measured. The mean concentration of vancomycin in the exudate from NPWT was 67% of the serum vancomycin concentration. We found that concentrations of vancomycin in NPWT exudates are higher than the previously reported concentrations in soft tissue without NPWT. The proactive use of NPWT might be considered in cases of suspected wound contamination when a systemic antibiotic is administered.     

负压创面治疗技术早期应用对软组织爆炸伤创面作用的研究

目的动态观察爆炸伤创面内细菌数量及病理改变，探讨负压创面治疗技术（NPWT）早期应用，对于控制软组织爆炸伤创面感染及肉芽生长的作用。方法采用猪爆炸伤软组织缺损模型，3只家猪随机分为一侧NPWT组，对侧为纱布敷料组，每组6个创面：另选取两只家猪形成的6个创面设为暴露组。致伤后分别于6h及第3、5、7天取各组创面中央组织行细菌定量，创面组织培养．HE染色观察肉芽生长情况。结果治疗前各组间细菌数无统计学差异。治疗后各时间点NPWT组细菌计数较纱布组、暴露组数值小。治疗后第3天NPWT组计数达到最高，第5天细菌计数降至感染临界值水平以下。NPWT治疗后创面面积缩小．深度变浅。NPWT组治疗后第3天肉芽组织新生较纱布组多，成纤维细胞、血管内皮细胞染色明显．组织细胞水肿减轻。结论NPWT早期应用能有效抑制爆炸伤创面细菌增殖，促进肉芽生长。     

Papel de la terapia presión negativa en la prevención de infección del sitio quirúrgico en cirugía colorrectal

BackgroundSurgical site infection (SSI) is one of the most frequent complications in colorectal surgery. It is diagnosed in 10 - 20% of colorectal procedures. Negative Pressure Wound Therapy (NPWT) has shown efficacy in the treatment of chronic and traumatic wounds, wound dehiscence, flaps and grafts. The main objective of this study is to assess NPWT in the prevention of SSI in colorectal surgery. Hospital stay reduction and SSI risk factors are secondary objectives.MethodsWe present a prospective case-control study including 80 patients after a colorectal diagnosis and surgical procedure (elective and non-elective) in 2017. Forty patients were treated with prevention NPWT for one week. Forty patients were treated according to the standard postoperative surgical wound care protocol.ResultsNo significant differences were found in demographic variables, comorbidities, surgical approach, elective or non-elective surgery, mechanical bowel preparation and surgical procedure. Three patients has SSI in the NPWT group (8%) (95%CI 0 – 17.5). Ten patients presented SSI in the control group (25%) (95%CI 12.5 – 37.5) (p = 0.034); OR 0.7 (95%CI 0.006-0.964). Hospital stay in the NPWT group was 8 days versus 12 days in the non-NPWT group (p = 0.22). In the multivariate analysis, mechanical bowel preparation was found to be the only risk factor for SSI (p = 0.047; OR: 0.8, CI 0.45-0.93).ConclusionsNPWT is a useful SSI prevention treatment in colorectal surgery.     

Negative pressure wound therapy in acute,contaminated wounds: documenting its safety and efficacy to support current global practice

Negative pressure wound therapy (NPWT) is in widespread use and its role in wound care is expanding worldwide. It is estimated that 300 million acute wounds are treated globally each year. Currently, sporadic data exist to support NPWT in acutely contaminated wounds. Despite lack of data, use of negative pressure wound therapy in such cases is increasing across the globe. We retrospectively reviewed 86 consecutive patients, totalling 97 contaminated wounds. All wounds were Class IV based on US Center for Disease Control criteria. Sepsis criteria were present in 78/86 (91%) of patients. All patients were managed with NPWT. Wound type, degree of tissue destruction, presence of infection, wound dimension, timing of initial NPWT, type and timing of wound closure and patient comorbidities were recorded. Outcome endpoints included durability of wound closure and death. Wound location was 41/97 (42%) in the torso; 56/97 (58%) at the extremities. Tissue necrosis was present in 84/97 (87%) of wounds. Infection was present in 86/97 (89%) of wounds. Average wound size was 619 cm² when square surface area measured; 786 cm³ when volume measurements taken. Mean time to wound closure was 17 days, median 10 days and mode 6 days. Durability of wound closure 73/79 (92%). Deaths were noted in 6/86 (7%) of patients. No deaths appeared related to NPWT. Contemporary NPWT related acute wound care is expanding empirically, in quantity and scope across the globe. However, several areas of concern are known regarding this contemporary use of NPWT in acute wounds. Thus, it is important to assess the safety and efficacy of such expanded empiric NPWT practice. Based on our findings with NPWT in the largest known patient cohort of this type, NPWT appears safe and effective in managing acute, contaminated wounds including patients meeting sepsis criteria. These findings provide evidence‐based support for current worldwide empiric NPWT‐related acute wound care.     

Clinical evaluation of gauze‐based negative pressure wound therapy in challenging wounds

The aim of this randomised clinical study was to evaluate the effectiveness and safety of gauze‐based negative pressure wound therapy (NPWT) in patients with challenging wounds. A total of 50 consecutive patients who had wound drainage for more than 5 days, required open wound management and had existence of culture positive infection were included the study. In this study, gauze‐based NPWT was compared with conventional dressing therapy in the treatment of patients with difficult‐to‐heal wounds. The patients were randomly divided into two groups. Group I (n = 25) was followed by conventional antiseptic (polyhexanide solution) dressings, and group II (n = 25) was treated with saline‐soaked antibacterial gauze‐based NPWT. The wounds' sizes, number of debridement, bacteriology and recurrence were compared between group I and group II. The mean age of the patients was 59·50 years (range 23–97). In group I, average wound sizes of pre‐ and post‐treatment periods were 50·60 ± 55·35 and 42·50 ± 47·92 cm², respectively (P < 0·001). Average duration of treatment was 25·52 ± 16·99 days, and average wound size reduction following the treatment was 19·99% in this group. In group II, the wounds displayed considerable shrinkage, accelerated granulation tissue formation, decreased and cleared away exudate. The average wound sizes in the pre‐ and post‐treatment periods were 98·44 ± 100·88 and 72·08 ± 75·78 cm², respectively (P < 0·001). Average duration of treatment was 11·96 ± 2·48 days, and average wound size reduction following the treatment was 32·34%. The patients treated with antibacterial gauze‐based NPWT had a significantly reduced recurrence (2 wounds versus 14 wounds, P = 0·001), and increased number of the culture‐negative cases (22 wounds versus 16 wounds, P < 0·047) in a follow‐up period of 12 months. There was a statistically significant difference between two groups in all measurements. As a result, we can say that the gauze‐based NPWT is a safe and effective method in the treatment of challenging infective wounds when compared with conventional wound management.     

Evaluation of wound healing effects of micronized acellular dermal matrix in combination with negative pressure wound therapy: In vivo study

Acellular dermal matrix (ADM) grafts can provide coverage for full-thickness skin defects and substitute for dermal defects. We tested the effectiveness of micronized ADM (mADM) as a dressing material, combined with negative pressure wound therapy (NPWT), for managing superficial wounds. We compared the wound healing effect of mADM in combination with NPWT with those of gelatin and mADM applied with a foam dressing. These therapeutic materials were applied to 36 cm² excisional wounds in a porcine full-thickness skin defect model. Wound healing kinetics and new tissue formation were assessed 10 days after the initial treatment by measuring the wound area. Collagen deposition and neovascularization were histologically evaluated. Compared with the other two groups, mADM plus NPWT combination group had a significantly larger wound area at the baseline (P = .0040), but the smallest on the 7th day (P = .0093). In addition, collagen formation and neovascularization were more histologically promoted than in the other two groups. mADM showed better results than the gelatin group but less collagen and revascularization than the combination group, and there was no significant difference in wound area. Our results show that the combination of mADM and NPWT has a synergistic wound healing effect.     

Management of the open abdomen using negative pressure wound therapy with instillation in severe abdominal sepsis: A review of 48 cases in Hospital Mexico,Costa Rica

IntroductionDespite the numerous advances in recent years, severe abdominal sepsis (with associated organ failure associated with infection) remains a serious, life-threatening condition with a high mortality rate. OA is a viable alternative to the previously used scheduled repeat laparotomy or continuous peritoneal lavage. The use of Negative Pressure Wound Therapy (NPWT) has been described as a successful method of management of the open abdomen. Adding instillation of saline solution to NPWT in a programmed and controlled manner, could offer the clinician an additional tool for the management of complex septic abdomen.ObjectivesTo explore if the concept of active two-way therapy (Negative pressure wound therapy with instillation or NPWT-I) yields superior control of underlying, life-threatening abdominal infections and its effects on survival and morbidity in patients with severe abdominal sepsis when management with an open abdomen is required.MethodsA retrospective review of 48 patients with severe abdominal sepsis, who were managed with and open abdomen and NPWT-I was performed. NPWT-I was initiated utilizing the same parameters on all patients, this consisted of cycles of instillation of saline solution, which was removed through negative pressure after a short dwell period. We observed the effects on primary fascia closure rate, mortality, hospital and SICU length of stay and associated complications.ResultsOur patient group consisted of 20 (42%) males and 28 (58%) females. Average age was 48 years. Mortality in these patients was attributed to pulmonary embolism (n = 1), acute renal failure (n = 2) and cardiopulmonary arrest (n = 1). Average total hospital stay was 24 days, and stay in the SICU (n = 26) averaged 7.5 days.No acute complications related to the NPWT-I. All patients presenting with abdominal compartment syndrome resolved after initiation of the NPWT-I. A total of 46 patients (96%) patients achieved fascia closure after NPWT-I therapy after an average of 6 days. Four patients (8%) died during the course of treatment of causes unrelated to NPWT-I.ConclusionThis therapy showed added benefits when compared to traditional methods such as ̈Bogota bag̈, Wittmann patch, or NPWT traditional in the management of the open abdomen pertaining to severe abdominal sepsis.NPWT-I in patients with severe abdominal sepsis had promising results, since we obtained higher fascia closure rates, lower mortality and reduced hospital and ICU length of stay with no complications due to this therapeutic approach.     

Outcomes of topical phenytoin in the management of traumatic wounds

IntroductionRegular dressing of traumatic wounds is of paramount importance for healing. Phenytoin, an anticonvulsant, is thought to promote wound healing through multiple mechanisms, including fibroblast proliferation, granulation tissue formation, antibacterial activity, and pain alleviation.AimTo assess the effect of topical phenytoin on traumatic wound healing in terms of granulation tissue formation, pain alleviation, and time taken for wound healing.MethodologyFifty patients with traumatic wounds were divided into equal and comparable groups. After cleaning the wound, phenytoin dressing was done in the study group and saline dressing in the control group. Thereafter, regular dressings of the wounds were done, and healing was assessed on day 14 and day 21.ResultsOn day 14, the wound surface area, percentage of granulation tissue, VAS score amongst cases was 39.4 ± 29.75 cm², 82.12 ± 9.71%, 4.52 ± 1.08, and that of controls was and 51.28 ± 25.33 cm², 62.72 ± 9.01%, 6.52 ± 1.22, respectively. On day 21, the wound surface area, percentage of granulation tissue, VAS score amongst cases were 29.4 ± 29.88 cm², 92 ± 4.46%, 2.8 ± 0.94, and that of controls were 38.92 ± 23.24 cm², 78.56 ± 8.19%, and 4.88 ± 1.17, respectively. The time taken for wound healing was 21.76 ± 5.28 days amongst cases and 31.64 ± 8.31 days amongst controls. Staphylococcus aureus was the commonest organism isolated in both the groups. On day 14,18(72%), wounds in the study group showed negative culture, whereas, in the control group, it was negative in 12 (48%) patients. The rate of granulation tissue formation was higher in cases when compared to controls amongst smokers and diabetics. The difference in all these parameters between the groups was statistically significant (P-value <0.05).Discussion and conclusionWe observed a considerable increase in granulation tissue formation, pain alleviation, and reduction in time taken for wound healing. Topical phenytoin is a safe, effective, readily available, and frugal agent that can accelerate wound healing through its multimodal action, thus reducing patient morbidity and economic burden.MeSH termsPhenytoin, Wound healing, Topical, Ulcer, Anticonvulsant, Granulation Tissue, Saline dressing.     

Negative pressure wound therapy reduces incidence of postoperative wound infection and dehiscence after long-segment thoracolumbar spinal fusion: a single institutional experience

Background contextWound dehiscence and surgical site infections (SSIs) can have a profound impact on patients as they often require hospital readmission, additional surgical interventions, lengthy intravenous antibiotic administration, and delayed rehabilitation. Negative pressure wound therapy (NPWT) exposes the wound site to negative pressure, resulting in the improvement of blood supply, removal of excess fluid, and stimulation of cellular proliferation of granulation tissue.PurposeTo assess the incidence of wound infection and dehiscence in patients undergoing long-segment thoracolumbar fusion before and after the routine use of NPWT.Study designRetrospective study.Patient sampleOne hundred sixty patients undergoing long-segment thoracolumbar spine fusions were included in this study.Outcome measuresPostoperative incidence of wound infection and dehiscence.MethodsAll adult patients undergoing thoracolumbar fusion for spinal deformity over a 6-year period at Duke University Medical Center by the senior author (CB) were included in this study. In 2012, a categorical change was made by the senior author (CB) that included the postoperative routine use of incisional NPWT devices after primary wound closure in all long-segment spine fusions. Before 2012, NPWT was not used. After primary wound closure, a negative pressure device is contoured to the size of the incision and placed over the incision site for 3 postoperative days. We retrospectively review the first 46 cases in which NPWT was used and compared them with the immediately preceding 114 cases to assess the incidence of wound infection and dehiscence.ResultsOne hundred sixty (NPWT: 46 cases, non-NPWT: 114 cases) long-segment thoracolumbar spine fusions were performed for deformity correction. Baseline characteristics were similar between both cohorts. Compared with the non-NPWT cohort, a 50% decrease in the incidence of wound dehiscence was observed in the NPWT patient cohort (6.38% vs. 12.28%, p=.02). Similarly, compared with the non-NPWT cohort, the incidence of postoperative SSIs was significantly decreased in the NPWT cohort (10.63% vs. 14.91%, p=.04).ConclusionsRoutine use of incisional NPWT was associated with a significant reduction in the incidence of postoperative wound infection and dehiscence.     

Use of negative pressure wound therapy in patients with fracture-related infection more than doubles the risk of recurrence

PurposeFracture-related infection (FRI) is one of the most serious complications in orthopedic trauma surgery. Despite its widespread use, the role of Negative Pressure Wound Therapy (NPWT) remains controversial in the management pathway of FRI. The aim of this study was to assess the relationship between the application of NPWT and its duration and recurrence of infection in operatively treated FRI patients.Patients and MethodsThis is a retrospective cohort study based on the FRI database of three level 1 Trauma Centres. Included patients had to be at least 16 years of age and surgically treated for FRI between January 1st 2015 and September 1st 2020. Patients were subdivided in either the NPWT group, when NPWT was applied as part of the FRI treatment, or in the control group, when no NPWT had been applied. To limit confounding, patients were excluded if they (also) underwent NPWT prior to the diagnosis of FRI. The relation between the duration of NPWT during FRI treatment and the recurrence rate of infection was analyzed using a multivariable logistic regression model.ResultsA total of 263 patients were included, 99 in the NPWT group and 164 in the control group. The median duration of NPWT was 18.0 (IQR 15.8) days. In the NPWT group, 28 patients (28.3%) developed a recurrent FRI. In the control group, 19 patients (11.6%) had a recurrent FRI (p = 0.001, 95% CI [0.174 – 0.635]). In the NPWT group there were no significant differences in baseline characteristics between the recurrence and non-recurrence group. The duration of NPWT was associated with a higher risk of recurrence of infection (p = 0.013, OR 1.036, 95% CI [1.008 – 1.066]).ConclusionDelayed wound closure with the application of NPWT increased the risk of recurrence of infection in patients with soft tissue defects after FRI treatment. Therefore, it is advised to consider NPWT only as a short-term (e.g. few days) necessity to bridge the period until definitive wound closure can be established.     

Failure by congestion of pedicled and free flaps for reconstruction of lower limbs after trauma: the role of negative-pressure wound therapy

Lower limb reconstruction with pedicled or free flaps can be commonly compromised by venous insufficiency. This complication often leads to partial/complete flap necrosis and increases the risk of superinfection. Negative-pressure wound therapy (NPWT) is known to increase local blood flow, decrease edema, promote tissue granulation, and reduce the likelihood of soft tissue infection. This study aims to evaluate the effectiveness of NPWT in the treatment of congested pedicled and free flaps of the lower limb after reconstructions in lower limb traumas. A retrospective analysis was performed on four congested (pedicled and free) flaps on the lower limbs. NPWT was applied in all cases after partial flap debridement. NPWT was able to improve and resolve tissue edema and venous insufficiency, avoid further flap necrosis, and promote granulation. On NPWT removal, a split-thickness skin graft was applied on the wound, achieving complete and uneventful healing. NPWT is a useful instrument in managing flaps affected by venous insufficiency in lower limb reconstruction, although larger studies are necessary to better define the effectiveness and indications of NPWT in this setting.     

Non‐invasive assessment of negative pressure wound therapy using high frequency diagnostic ultrasound: oedema reduction and new tissue accumulation

Tissue oedema plays an important role in the pathology of chronic and traumatic wounds. Negative pressure wound therapy (NPWT) is thought to contribute to active oedema reduction, yet few studies have showed this effect. In this study, high frequency diagnostic ultrasound at 20 MHz with an axial resolution of 60 µm was used to assess the effect of NPWT at – 80 mmHg on pressure ulcers and the surrounding tissue. Wounds were monitored in four patients over a 3‐month period during which changes in oedema and wound bed thickness (granulation tissue) were measured non‐invasively. The results showed a rapid reduction of periwound tissue oedema in all patients with levels falling by a mean of 43% after 4 days of therapy. A 20% increase in the thickness of the wound bed was observed after 7 days due to new granulation tissue formation. Ultrasound scans through the in situ gauze NPWT filler also revealed the existence of macrodeformation in the tissue produced by the negative pressure. These preliminary studies suggest that non‐invasive assessment using high frequency diagnostic ultrasound could be a valuable tool in clinical studies of NPWT.     

The influence of different sizes and types of wound fillers on wound contraction and tissue pressure during negative pressure wound therapy

Negative pressure wound therapy (NPWT) contracts the wound and alters the pressure in the tissue of the wound edge, which accelerates wound healing. The aim of this study was to examine the effect of the type (foam or gauze) and size (small or large) of wound filler for NPWT on wound contraction and tissue pressure. Negative pressures between --20 and --160 mmHg were applied to a peripheral porcine wound (n = 8). The pressure in the wound edge tissue was measured at distances of 0·1, 0·5, 1·0 and 2·0 cm from the wound edge and the wound diameter was determined. At 0·1 cm from the wound edge, the tissue pressure decreased when NPWT was applied, whereas at 0·5 cm it increased. Tissue pressure was not affected at 1·0 or 2·0 cm from the wound edge. The tissue pressure, at 0·5 cm from the wound edge, was greater when using a small foam than when using than a large foam. Wound contraction was greater when using a small foam than when using a large foam during NPWT. Gauze resulted in an intermediate wound contraction that was not affected by the size of the gauze filler. The use of a small foam to fill the wound causes considerable wound contraction and may thus be used when maximal mechanical stress and granulation tissue formation are desirable. Gauze or large amounts of foam result in less wound contraction which may be beneficial, for example when NPWT causes pain to the patient.     

The Effect of Surgical Technique and Spacer Texture on Bone Regeneration: A Caprine Study Using the Masquelet Technique

Background

The Masquelet-induced-membrane technique is a commonly used method for treating segmental bone defects. However, there are no established clinical standards for management of the induced membrane before grafting.

Questions/purposes

Two clinically based theories were tested in a chronic caprine tibial defect model: (1) a textured spacer that increases the induced-membrane surface area will increase bone regeneration; and (2) surgical scraping to remove a thin tissue layer of the inner induced-membrane surface will enhance bone formation.

Methods

Thirty-two skeletally mature female goats were assigned to four groups: smooth spacer with or without membrane scraping and textured spacer with or without membrane scraping. During an initial surgical procedure (unilateral, left tibia), a defect was created excising bone (5 cm), periosteum (9 cm), and muscle (10 g). Segments initially were stabilized with an intramedullary rod and an antibiotic-impregnated polymethylmethacrylate spacer with a smooth or textured surface. Four weeks later, the spacer was removed and the induced-membrane was either scraped or left intact before bone grafting. Bone formation was assessed using micro-CT (total bone volume in 2.5-cm central defect region) as the primary outcome; radiographs and histologic analysis as secondary outcomes, with the reviewer blinded to the treatment groups of the samples being assessed 12 weeks after grafting. All statistical tests were performed using a linear mixed effects model approach.

Results

Micro-CT analysis showed greater bone formation in defects with scraped induced membrane (mean, 3034.5 mm³; median, 1928.0 mm³; quartile [Q]1–Q3, 273.3–2921.1 mm³) compared with defects with intact induced membrane (mean, 1709.5 mm³; median, 473.8 mm³; Q1–Q3, 132.2–1272.3 mm³; p = 0.034). There was no difference in bone formation between textured spacers (mean, 2405.5 mm³; median, 772.7 mm³; Q1–Q3, 195.9–2743.8 mm³) and smooth spacers (mean, 2473.2 mm³; median, 1143.6 mm³; Q1–Q3, 230.2–451.1 mm³; p = 0.917).

Conclusions

Scraping the induced-membrane surface to remove the innermost layer of the induced-membrane increased bone regeneration. A textured spacer that increased the induced-membrane surface area had no effect on bone regeneration.

Clinical Relevance

Scraping the induced membrane during the second stage of the Masquelet technique may be a rapid and simple means of improving healing of segmental bone defects, which needs to be confirmed clinically.