Microvascular free tissue transfer in acute and secondary burn reconstruction

Pedicled and Free Flap Lower Extremity Reconstruction in Acute Burn Injuries

BACKGROUND

A paucity of studies investigates the outcomes of flap reconstruction in lower extremity acute burns. The aim of this study is to report outcomes of lower extremity acute burn requiring pedicled or free flap coverage.

METHODS

A retrospective cohort study was conducted to compare the outcomes of patients undergone pedicled versus free flap reconstruction of acute lower extremity burns, between August 2010 and December 2022. Collected data included demographics, injury and flap characteristics, complications, and reoperations. χ2 tests were used to measure differences in complication rates between pedicled and free flaps.

RESULTS

A total of 28 patients were involved in the study. Among them, 17 patients underwent 28 pedicled flap procedures, while 11 patients received a single free flap surgery each. In the free flap group, the overall complication rate was 54.5%. In the pedicled flap group, the overall complication rate was 25.0%. Free flaps showed a significantly higher rate of total flap loss compared to pedicled flaps (18.2% vs 0%, P = 0.021). Other differences were not statistically significant.

CONCLUSIONS

Flap coverage in lower extremity acute burns is rarely employed. Yet, in case of critical structures exposure it is often necessary. However, it is important to be aware of the high risk of complications, especially for more complex reconstructions requiring free tissue transfer.

Impact of Microsurgical Reconstruction Timing on the Risk of Free Flap Loss in Acute Burns: Systematic Review and Meta-Analysis

Background

Free tissue transfer is usually considered as a last resort in severe burn cases, when skin substitutes and local flaps are not viable options. Prior studies have demonstrated a free flap loss rate ranging from 0% to 44%. The aim of this study is to identify the ideal timing to perform free flap reconstruction in acute burn-related injuries to minimize free flap loss.

Methods

A systematic review and meta-analysis was performed and reported according to PRISMA guidelines. PubMed, Embase, Web of Science, and Cochrane Library databases were queried. The review protocol was registered on PROSPERO database (CRD42023404478). Three time intervals from day of injury were identified: (1) 0-4 days, (2) 5-21 days, and (3) 22 days-6 weeks. The primary outcome was total free flap loss.

Results

A total of 17 articles met inclusion criteria. The analysis included 275 free flaps performed in 260 patients (88% men, 12% women) affected by acute burn injuries. The pooled prevalence of free flap failure in the three time intervals (0-4 days, 5-21 days, and 22 days-6 weeks) were 7.32% [95% confidence interval (CI): 2.38%-20.37%], 16.55% (95% CI: 11.35%-23.51%), and 6.74% (95% CI: 3.06%-14.20%), respectively.

Conclusions

Free flap reconstruction carries a high risk of failure in patients with acute burn. However, timing of the reconstruction appears to influence surgical outcomes. Free flap reconstruction performed between 5 and 21 days from burn injury had a trend toward higher flap loss rates and should be discouraged.

Free Flap Failure and Contracture Recurrence in Delayed Burn Reconstruction: A Systematic Review and Meta-analysis

Background

Free tissue transfer is often considered a last resort in burn reconstruction due to its complexity and associated risks. A comprehensive review on free flap outcomes in delayed burn reconstruction is currently lacking. The study aimed to evaluate the available evidence on the failure and contracture recurrence rates in free flap delayed burn reconstruction.

Methods

A systematic review and meta-analysis was conducted and reported according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. The protocol was registered on PROSPERO (CRD42023404478). The following databases were accessed: Embase, PubMed, Web of Science, and Cochrane Library. The measured outcomes were free flap loss and contracture recurrence rate.

Results

Of the 1262 retrieved articles, 40 qualified for inclusion, reporting on 1026 free flaps performed in 928 patients. The mean age was 29.25 years [95% confidence interval (CI), 24.63-33.88]. Delayed burn reconstruction was performed at an average of 94.68 months [95% CI, - 9.34 to 198.70] after initial injury, with a follow-up period of 23.02 months [95% CI, 4.46-41.58]. Total flap loss rate was 3.80% [95% CI, 2.79-5.16] and partial flap loss rate was 5.95% [95% CI, 4.65-7.57]. Interestingly, burn contracture recurrence rate was 0.62% [95% CI, 0.20-1.90].

Conclusions

This systematic review provides a comprehensive evaluation of the free flap outcomes in delayed burn reconstruction. The flap loss rate was relatively low, given the complexity of the procedure and potential risks. Furthermore, burn contracture rate was found to be extremely low. This study demonstrates that free flaps are a safe and effective option for delayed burn reconstruction.

Outcomes of Muscle versus Fasciocutaneous Free Flap Reconstruction in Acute Burns: A Systematic Review and Meta-analysis

Background

Free flap reconstruction in acute burns is high risk but often required for limb salvage and coverage of vital structures. Prior studies have shown a flap loss rate up to 44%. This study aimed to compare the complications associated with muscle and fasciocutaneous free flaps in acute burn reconstruction.

Methods

A systematic review and meta-analysis was conducted according to PRISMA guidelines and registered on the PROSPERO database (CDR42023471088). The databases accessed were Embase, PubMed, Web of Science, and Cochrane Library. The primary outcome was free flap failure rate based on flap type. Secondary outcomes included venous congestion, arterial thrombosis, amputation, and need for reintervention.

Results

Twelve studies with 181 free flaps were included: 87 muscle flaps and 94 fasciocutaneous flaps. Muscle flaps had a higher risk ratio (RR) for total flap loss [RR: 2.32, 95% confidence interval (CI): 1.01-5.32, P = 0.04], arterial thrombosis (RR: 3.13, 95% CI: 1.17-8.42, P = 0.02), and amputations (RR: 8.89, 95% CI: 1.27-70.13, P = 0.03) compared with fasciocutaneous flaps. No significant differences were found in venous thrombosis (RR: 1.33, 95% CI: 0.37-4.78, P = 0.65) or need for reinterventions (RR: 1.34, 95% CI: 0.77-2.32, P = 0.29).

Conclusions

Muscle flaps in burn injuries are associated with higher risks of flap failure, arterial thrombosis, and amputations. Fasciocutaneous free flaps in acute burns seem to be safer with better outcomes, though further research is needed to confirm these findings.

The Role of Microsurgery in Burn Surgery

Acute burn reconstruction involves intricate strategies such as skin grafting and innovative technologies, addressing challenges in coverage and minimizing donor site morbidity. Despite being rarely used, flap reconstruction becomes necessary when critical structures are exposed, offering robust coverage and reducing complications. However, free flaps in acute burns face challenges, including a higher failure rate attributed to hyperinflammatory states and hypercoagulability. Surgical optimization strategies involve careful timing, patient preparation, and meticulous postoperative care. In delayed burn reconstruction, free flaps proved effective in functional and aesthetic restoration, with low flap loss rates and minimal contracture recurrence. Prefabricated and prelaminated flaps emerged as a solution for complex cases, ensuring the best functional and aesthetic possible outcomes in challenging facial burn reconstructions.

Dihydromyricetin regulates KEAP1-Nrf2 pathways to enhance the survival of ischemic flap

In clinical flap practice, there are a lot of studies being done on how to promote the survival of distal random flap necrosis in the hypoxic and ischemic state. As a traditional Chinese medicine, dihydromyricetin (DHM) is crucial in preventing oxidative stress and apoptosis in a number of disorders. In this work, we examined the impact of DHM on the ability to survive of ischemia flaps and looked into its fundamental mechanism. Our results showed that DHM significantly increased the ischemic flaps' survival area, encouraged angiogenesis and blood flow, reduced oxidative stress and apoptosis, and stimulated KEAP1-Nrf2 (Kelch-like ECH-associated protein 1-nuclear factor erythroid 2-related factor) signaling pathways. Adeno-associated virus (AAV) upregulation of KEAP1 expression also negated the favorable effects of DHM on flap survival. By activating KEAP1-Nrf2 signaling pathways, DHM therapy promotes angiogenesis while reducing oxidative stress and apoptosis.

Free Flap Failure and Complications in Acute Burns: A Systematic Review and Meta-analysis

Background

Severe acute burn injuries represent a challenge to the reconstructive surgeon. Free flap reconstruction might be required in cases of significant critical structure exposure and soft tissue deficits, when local options are unavailable. This study aimed to determine the free flap complication rate in acute burn patients.

Methods

A systematic review and meta-analysis were conducted and reported according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines and registered on the International Prospective Register of Systematic Reviews database (CRD42023404478). The following databases were accessed: Embase, PubMed, Web of Science, and Cochrane Library. The primary outcome was the free flap failure rate.

Results

The study identified 31 articles for inclusion. A total of 427 patients (83.3% men, 16.7% women) accounting for 454 free flaps were included. The mean patient age was 36.21 [95% confidence interval (CI), 31.25-41.16]. Total free flap loss rate was 9.91% [95% CI, 7.48%-13.02%], and partial flap loss was 4.76% [95% CI, 2.66%-8.39%]. The rate of venous thrombosis was 6.41% [95% CI, 3.90%-10.36%] and arterial thrombosis was 5.08% [95% CI, 3.09%-8.26%]. Acute return to the operating room occurred in 20.63% [16.33%-25.71%] of cases. Stratified by body region, free flaps in the lower extremity had a failure rate of 8.33% [95% CI, 4.39%-15.24%], whereas in the upper extremity, the failure rate was 6.74% [95% CI, 3.95%-11.25%].

Conclusion

This study highlights the high risk of free flap complications and failure in acute burn patients.

Free Tissue Transfer in the Reconstruction of Neck Contractures after Burn Injury: A Case Series

Background: Recent advances in burn care have significantly improved the survival rate of patients with extensive burn injuries, placing greater emphasis on reconstruction to improve the long-term outcomes of scar deformities. Anterior and lateral neck contractures are common after burn injuries; they limit range of motion, complicate airway management and create significant cosmetic deformities. Traditional methods have been used to release contractures and improve function. However, they are subject to variable results, residual neck tightness, recurrence and suboptimal cosmetic appearance. Microvascular free tissue transfer is a more technically challenging and time-consuming method, but it offers the potential to overcome the long-term limitations of simpler options. In this paper, we present our experience with microvascular free flaps for the release of burn scar contractures of the neck as a potential high-quality permanent solution. Methods: Over a 10-year period, nine free flaps were performed on burn patients with total body surface area (TBSA) burns between 20 and 70%, who developed moderate to severe neck contractures. Four anterolateral thigh (ALT) flaps, four radial forearm free flaps (RFFFs) and one ulnar forearm flap were used to release neck contractures. Results: All nine flaps were completed successfully with significant improvement in the neck's range of motion. Good aesthetic results were achieved with smooth contour and thin coverage. Overall, the patients were satisfied. However, five out of nine cases required at least one secondary procedure for flap defatting to reach optimal results. Conclusion: Post-burn scar contractures of the cervical region compromise the cosmetic appearance and airway security of recovering burn patients, imposing a significant impact on their psychological and functional quality of life. Consequently, cervical contractures can be prioritized when planning reconstruction for burn patients. Free flaps can be considered an important and reliable method of reconstruction for neck contracture deformity following burn injuries.

Predictors for limb amputation and reconstructive management in electrical injuries

BACKGROUND

Electrical injuries follow a specific pathophysiology and may progressively damage both skin and deeper tissues, frequently ending in amputations. Type and timing of soft tissue reconstruction after electrical burns is crucial for proper outcome. The aim of this study was to assess surgical management and outcome of patients with electrical injuries treated at the Zurich Burn Center over the last 15 years, with emphasis on risk factors for amputation and reconstructive strategy.

METHODS

Patient charts were reviewed retrospectively to identify cases admitted at the Zurich Burns Center (2005-2019). Patient characteristics and surgical management, with a special focus on amputations, reconstruction and outcome were analyzed and risk factors for amputation were assessed.

RESULTS

Eighty-nine patients were identified and a total of 522 operations were performed. Escharotomy and fasciotomies were performed in 40.5% and 24.7% of cases, respectively, mainly at admission. The total amputation rate was 13.5% (23 amputations, 12 patients). Development of compartment syndrome, rhabdomyolysis, high myoglobin and CK blood levels, kidney failure, sepsis and respiratory complications during the course were related to higher risk of amputation (p < 0.001). Sixty-six flap-based reconstructions were performed (25% cases): 49 loco-regional flaps, 3 distant pedicled flaps, 14 free flaps. Two flaps were lost (flap failure rate 14%). Both flap losses occurred in cases of early reconstruction (within 5-21 days).

CONCLUSIONS

Electrical injuries are still cause of elevated morbidity and mortality, with high amputation rate. Predictors for amputation can support physicians in the surgical care and decision-making. Reconstruction remains challenging in this type of injury: the surgical management with early decompression, serial necrectomies and delayed early reconstruction remains the procedure of choice at our unit.

Flap failure prediction in microvascular tissue reconstruction using machine learning algorithms

BACKGROUND

Microvascular tissue reconstruction is a well-established, commonly used technique for a wide variety of the tissue defects. However, flap failure is associated with an additional hospital stay, medical cost burden, and mental stress. Therefore, understanding of the risk factors associated with this event is of utmost importance.

AIM

To develop machine learning-based predictive models for flap failure to identify the potential factors and screen out high-risk patients.

METHODS

Using the data set of 946 consecutive patients, who underwent microvascular tissue reconstruction of free flap reconstruction for head and neck, breast, back, and extremity, we established three machine learning models including random forest classifier, support vector machine, and gradient boosting. Model performances were evaluated by the indicators such as area under the curve of receiver operating characteristic curve, accuracy, precision, recall, and F1 score. A multivariable regression analysis was performed for the most critical variables in the random forest model.

RESULTS

Post-surgery, the flap failure event occurred in 34 patients (3.6%). The machine learning models based on various preoperative and intraoperative variables were successfully developed. Among them, the random forest classifier reached the best performance in receiver operating characteristic curve, with an area under the curve score of 0.770 in the test set. The top 10 variables in the random forest were age, body mass index, ischemia time, smoking, diabetes, experience, prior chemotherapy, hypertension, insulin, and obesity. Interestingly, only age, body mass index, and ischemic time were statistically associated with the outcomes.

CONCLUSION

Machine learning-based algorithms, especially the random forest classifier, were very important in categorizing patients at high risk of flap failure. The occurrence of flap failure was a multifactor-driven event and was identified with numerous factors that warrant further investigation. Importantly, the successful application of machine learning models may help the clinician in decision-making, understanding the underlying pathologic mechanisms of the disease, and improving the long-term outcome of patients.

Timing of Flap Surgery in Acute Burn Patients Does Not Affect Complications

Pedicled and free flaps are occasionally necessary to reconstruct complex wounds in acute burn patients. Flap coverage has classically been delayed for concern of progressive tissue necrosis and flap failure. We aim to investigate flap complications in primary burn care leveraging national U.S. data. Acute burn patients with known % total body surface area(TBSA) were extracted from the Nationwide/National Inpatient Sample from 2002 to 2014 based on the International Classification of Disease (ICD) codes, ninth edition. Variables included age, sex, race, Elixhauser index, %TBSA, mechanism, inhalation injury, and location of burn. Flap complication was defined by ICD-9 procedure code 86.75, return to the operating room for flap revision. Multivariable analysis evaluated predictors of flap compromise using stepwise logistic regression with backward elimination. The weighted sample included 306,924 encounters of which 526 received a flap (0.17%). About 7.8% of flap encounters sustained electric injury compared to 2.7% of non-flap encounters (odds ratio [OR] 3.76, 95% confidence interval [CI] 1.95-7.24, P < .001). The mean hospital day of the flap procedure was 10.1 (SD 10.7) days. Flap complications occurred in 6.4% of cases. The timing of flap coverage was not associated with complications. The only independent predictor of flap complication was electrical injury (OR 40.49, 95% CI 2.98-550.64, P = .005). Electrical injury was an independent predictor of flap complications compared to other mechanisms. Flap timing was not associated with return to surgery for complications. This suggests that the use of flaps is safe in acute burn care to achieve burn wound closure with an understanding that electrical injuries may warrant particular consideration to avoid failure.

Bilateral Lower Limb Salvage after Fourth-degree Burns: Subscapular Axis Free and Chimeric Flaps Effectiveness in Complex Reconstruction

Microsurgery is usually required for reconstruction of complex lower limb defects, preserving otherwise unsalvageable injuries. Fourth-degree burns are severe traumatic injuries. A case of bilateral lower limb salvage through a resourceful use of subscapular axis free and chimeric flaps for acute burn reconstruction of extensive lower leg injuries is reported. A 48-year-old man sustained a 40% surface area flame burn, circumferential and full-thickness at the lower limbs. Debridement of fourth-degree burns of the anterior lower legs resulted in bone exposure of the left and right tibias, right medial malleolus, and Achilles tendon. A latissimus dorsi (LD) flap plus a chimeric subscapular axis free flap with 3 components (LD, serratus anterior (SA), and parascapular) were designed for reconstruction. LD insetting for left tibia coverage with anastomoses to anterior tibial vessels was performed. Right side flap insetting provided tibia coverage with LD; medial malleolus with SA; and Achilles tendon with parascapular flap. An anatomical variation required anastomoses to proximal (chimeric LD + SA) and distal (parascapular) ends of posterior tibial vessels because of an independent origin of the pedicles. At 10-months follow-up after intensive rehabilitation, the patient showed proper functional outcomes at daily-life and work activities with autonomous walking using a single crutch. This case highlights the importance of microsurgery and chimeric flaps for limb salvage in extreme situations. The authors review and discuss the surgical options, emphasizing specific considerations of microsurgical reconstruction in burn patients.

Free tissue transfer for burns reconstruction: A single-site experience

This study reviews free tissue transfer (FTT) surgery for both acute wound and reconstructive scar management of burn injuries at a UK burns unit over a 10-year period. Thirty eight patients underwent 46 FTTs, or free flaps, as part of their burn injury pathway. For the cohort of patients, there was one flap failure, which occurred for a secondary scar reconstruction. It is noted that FTT was successful for all seven acute or primary interventions. Anterolateral thigh flap was the most frequently performed (57%); followed by parascapular flaps (22%) of which 43% were pre-expanded. A method of pre-expansion for neck contractures and a novel technique of anchoring this flap to the pre-tracheal fascia are described here. This can provide the patient with good neck contouring by using the capsule to hitch the flap into a good position. It is clear that further work is required to study the prevention of hypertrophic scarring that can occur at the interface between flap and adjacent skin, where occurrence rate in this cohort was 17%. It is proposed that FTT now provides a viable solution both to the coverage of complex burn wounds and to the revision of scar contractures. Consensus over an FTT protocol for the primary management of open burn wounds is seen as the logical next step for this surgical intervention.

Free-style puzzle flap as a cross-leg pedicled flap: the concept of re-using a flap in acute burns, a case report

Background

In well-selected cases, flaps can play a pivotal role in optimizing outcomes in the acute phase of burns. A previous redundant flap could be reused or recycled as a donor site from which a new flap could be raised.

Case presentation

We report the case of a patient with full thickness burns on both legs, leading to the exposure of joints of the right ankle and the right foot and left patellar tendon. The right lower extremity was covered with a free musculo-cutaneous latissimus dorsi flap. Then, a musculo-cutaneous cross-leg flap pedicled on the anterior branch and centered on a perforator was harvested from the previous redundant flap to cover the controlateral knee.

Conclusion

Sequential flap coverage can be considered in cases of extensive soft tissue defects and particularly in burns. This case illustrates that re-using a redundant part of a previous flap to cover another defect is a safe and interesting alternative in the event of a lack of donor sites or to save donor sites for later reconstruction of contracted burn scars.

Burns in Children

Children have a great deal to gain from recent and future advances in burn care. A very broad range of realized and potential developments are involved. These will be very briefly reviewed within the context of four areas: 1) early evaluation and care issues, 2) acute surgical and critical care issues, 3) rehabilitation and reconstruction issues, and 4) organizational and outcomes issues.