Lower Extremity Free Flap Reconstruction Research Articles

The Effect of Regional Anaesthesia on Free Flap Survival in Lower Extremity Reconstructions.

The effect of different modalities of anaesthesia in microvascular free flap surgery has been a topic of ongoing debate. Comparative data to study the effect of general anaesthesia and regional anaesthesia in the form of peripheral nerve blocks (PNBs) on lower extremity free flap survival is lacking to date. This study aims to elucidate the effect of regional anaesthesia on flap survival in lower extremity free flap reconstructions. A retrospective cohort study of all patients who underwent free vascularised flap reconstruction of the lower extremities between 2012 and 2021 at the Amsterdam University Medical Centre (UMC), The Netherlands, and between 2019 and 2021 at the Radboud UMC, Nijmegen, The Netherlands. In this cohort, we analysed partial and total flap failures. In this cohort, 87 patients received a total of 102 microvascular free flap reconstructions of the lower extremity. In 20.5% of these operations, patients received a supplemental PNB. Total flap failure was 23.8% in the regional anaesthesia group compared to 21% in the group with general anaesthesia only (p = 0.779). Operation time was longer for patients with regional anaesthesia (p = 0.057). Length of stay was on average 2 days shorter for patients with supplemental regional anaesthesia (p = 0.716). This is the largest cohort comparing flap survival in patients receiving general anaesthesia to general anaesthesia with a PNB in lower extremity reconstructions to date. We cannot attribute a significant beneficial or detrimental effect of regional anaesthesia to flap survival. High failure rates stress the need for future studies. Koster ITS, den Os MM, Rutten MVH, et al. The Effect of Regional Anaesthesia on Free Flap Survival in Lower Extremity Reconstructions. Strategies Trauma Limb Reconstr 2024;19(1):15-20.

Free Flaps in Patients with Advanced Arteriosclerosis of the Tibial Vessels: Mini Vein Graft to the Peroneal Artery.

Lower extremity reconstruction with free flaps in patients with only peroneal artery runoff remains a challenge. Here, we present a novel technique for reconstruction of medial defects in the distal leg using a medial approach to the peroneal artery and a short interposition vein graft anastomosed end to side to the peroneal artery. A retrospective, single-center study was performed including all patients who underwent lower extremity reconstruction with free flaps anastomosed to the peroneal artery using a mini vein graft from November 2020 to March 2022. The primary outcome measure was limb salvage. Secondary endpoints were flap survival and postoperative complications. Seven patients received lower extremity free flap reconstruction with a mini vein graft to the peroneal artery. Flap loss rate was 0%. Limb salvage was achieved in five patients (71%). At 6-month follow-up, all patients were ambulatory. One patient died 1 month after surgery due to heart failure. Mini vein graft to the peroneal artery allows reliable and safe free flap reconstruction of distal leg defects in patients with only peroneal artery runoff.

Patient-reported esthetic outcomes following lower extremity free flap reconstruction: A cross-sectional multicenter study

IntroductionThe goal of lower-extremity reconstructions is primarily to salvage the leg; however, esthetic outcomes are also important. This study aimed to assess the impact of a lower extremity free tissue transfer regarding social functioning, patient-reported esthetic outcomes, and possible differences between fasciocutaneous vs. muscle flaps. Material and MethodsFor this cross-sectional multicenter study, patients operated between 2003 and 2021, with a minimum follow-up of 12 months, were identified. Outcomes were obtained from 89 patients. Patient-reported outcomes were assessed using a questionnaire containing 5-point Likert scale questions grouped in three groups: aspect of the reconstructed leg, the aspect of the donor site, and the negative impact on social functioning. Physical functioning and mental health were assessed with the Short-Form-36. ResultsThe overall score for negative impact on social functioning was 22.2. This was 46.7 for the esthetic satisfaction of the reconstructed leg and 57.1 for the donor site. No significant differences were seen between patients who underwent a reconstruction with a fasciocutaneous flap compared to a muscle flap. Secondary surgical procedures for improving the esthetic aspect were performed in 12% of the patients in the fasciocutaneous group and 0% in the muscle group. ConclusionOur results show that the most optimal esthetic outcome is not defined by the type of flap. We found a strong correlation between physical functioning and the negative impact on social functioning that a reconstructed lower extremity may have. The result of this study can be taken into consideration during the shared decision-making process of choosing the most optimal reconstruction.

The Hidden Risks of Perioperative Transfusions in Traumatic Lower Extremity Free Flap Reconstruction.

Blood transfusions have been associated with surgical complications; however, these studies are not specific to lower extremity (LE) reconstruction. We evaluated the effect of perioperative packed red blood cell (PRBC) transfusions on LE free flap outcomes in trauma patients. Patients undergoing LE free flap reconstruction following acute injuries from 2016 to 2021 were retrospectively analyzed. The perioperative period for transfusions was defined as ± 3 days from the procedure. Parameters included demographics, perioperative characteristics, and outcomes. Major complications were complications requiring reoperation. Univariate and multivariate analyses were performed to identify associations. Of the 205 patients, 48% received PRBCs perioperatively. There was a trend toward higher major complications rate in the transfusion group (19 vs. 10%, p = 0.09). Wound size, injury severity score (ISS), and intraoperative estimated blood loss were greater in the transfusion group (p < 0.01). Preoperative hemoglobin/hematocrit were lower in the transfusion group (p < 0.001). Units of PRBCs transfused were independently associated with major complications on multivariate analysis (odds ratio [OR] = 1.34, confidence interval [CI]: 1.06-1.70, p = 0.015) and length of hospital stay (LOS; OR = 1.05, CI: 1.02-1.08, p = 0.002). Infection, wound size, ISS, and preoperative hemoglobin/hematocrit were independently associated with increased LOS (p < 0.05) but not with major complications. The number of units of PRBCs given perioperatively was the only variable independently associated with major complications on multivariate analysis and was one of many variables associated with increased LOS. These findings suggest the usage of restrictive transfusion protocols in trauma patients requiring LE reconstruction.

Discussion: Secondary Surgery after Lower Extremity Free Flap Reconstruction.

Discussion: Secondary Surgery after Lower Extremity Free Flap Reconstruction.

POSTOPERATIVE PROTOCOLS FOR LOWER EXTREMITY FREE FLAP RECONSTRUCTIONS: A NATIONAL SURVEY OF UK MAJOR TRAUMA CENTRES

IntroductionDespite the established guidelines on lower extremity free flap reconstruction by the British Orthopaedic Association Standard for Trauma (BOAST-4) the post-operative care has yet to be standardised. There is currently no coherent evidence in the literature regarding clinical monitoring, warming, dangling and compression; the optimal regimes and their respective physiological benefits. The aim of this study is to survey all UK Major Trauma Centres (MTCs) with regards to the post-operative care of lower extremity free flaps and elucidate the current protocols for clinical monitoring, warming, dangling and compression.Materials &amp; MethodsAll UK-based adult MTCs were surveyed. We formulated a detailed questionnaire to enquire about the post-operative care of lower extremity free flap reconstructions; the number of free flap reconstructions per month and take backs per month and for which post-operative methods a protocol is used in each MTC. We asked specific questions concerning: clinical monitoring, warming, dangling and compression. This questionnaire was distributed to consultant leads in the form of multiple choice questions, with an option of free-text box for further comments, using JISC online surveys. Results were analysed in Excel and presented in percentages.ResultsThe 28 adult MTCs were contacted. The results showed a lack of formal regional protocols with great variability, suggesting there is no general consensus on post-operative care of lower extremity free flap reconstructions with regards to clinical monitoring, warming, dangling and compression.ConclusionsThis survey of UK MTCs on the post-operative protocols for lower extremity free flap reconstruction demonstrated lack of evidence, consensus and large variability in common practice which requires standardisation.

D27. Effect of Postoperative Anticoagulation Regimen on Lower Extremity Free Flap Outcomes

PURPOSE: Free flap reconstruction for lower extremity (LE) trauma has a higher failure rate than in other anatomic regions. Anticoagulation selection in the immediate postoperative period may influence free flap outcomes. This study evaluates complication rates associated with varying anticoagulation protocols among LE free flap reconstruction. METHODS: Patients with LE trauma with free flap reconstruction from 2016-2021 were included for retrospective chart review. Complications were divided into major (hematoma, flap thrombosis, flap necrosis >10%, infection requiring reoperation) and minor (wound dehiscence, flap necrosis <10%, infection treated with antibiotic alone) categories. Patients were categorized into 4 groups based on postoperative anticoagulation regimen (aspirin, heparin drip, aspirin + heparin drip, and DVT-prophylaxis only). Complication rates were compared between each group. Univariate analysis was performed using ANOVA and chi-squared tests. Multivariable analysis was performed with a generalized linear model to predict any major complications. P values were set at P<0.05. RESULTS: Of 199 patients, 18.6% received aspirin only, 38.2% received heparin drip only, 39.2% received aspirin + heparin drip, and 4.0% received DVT prophylaxis only. Demographics were similar between the groups. Major complication rates were negatively correlated with the aspirin group (p=0.001) and the heparin drip group (p=0.031). CONCLUSION: In patients with LE free tissue transfer after acute trauma, postoperative use of aspirin only or heparin drip only results in fewer complications than aspirin + heparin drip or DVT-prophylaxis alone.

A Retrospective Matched-Pair Analysis of Long-term Outcomes after Successful Lower Extremity Free Flap Salvage.

Pedicle occlusion with total free flap loss after microvascular lower extremity reconstruction is a considerably rare yet devastating complication. Fortunately, in the majority of cases, emergency salvage takebacks of compromised free flaps are initiated in a timely manner. In this report, we present our analysis of long-term outcomes following transient vascular compromise mitigated through successful free flap salvage in the lower extremity. We performed a single-center retrospective matched-pair analysis of 46 patients with lower extremity free flap reconstructions. Cases underwent successful revisions of microvascular compromise (n = 23), whereas controls had uneventful postoperative courses (n = 23). Patient-reported outcome questionnaires and physical evaluations were used to assess general quality of life, functional outcomes, and cosmesis (Lower Extremity Functional Scale [LEFS], Lower Limb Outcomes Questionnaire [LLOQ], Short Form 36 (SF-36), Vancouver Scar Scale [VSS]). The mean follow-up time was 4.4 years. The health-related quality of life assessed by the SF-36 did not differ significantly between both groups in any of the subscales (p ≥ 0.15 for all subscales). Functional outcomes did not show significant differences between both groups according to the LEFS (p = 0.78) and LLOQ (p = 0.45). The overall scar appearance assessed by the VSS showed significantly poorer cosmesis in the re-exploration group (p = 0.014). Salvage of compromised free flaps in the lower extremity yields similar long-term outcomes compared to noncompromised free flaps with regard to function and quality of life. However, free flap revisions may lead to impaired scar formation. This study provides further evidence that the opportunity for urgent re-exploration is indispensable.

Updates in Traumatic Lower Extremity Free Flap Reconstruction.

Lower extremity reconstruction, particularly in the setting of trauma, remains one of the most challenging tasks for the plastic surgeon. Advances in wound management and microsurgical techniques in conjunction with long-term outcomes studies have expanded possibilities for limb salvage, but many aspects of management have continued to rely on principles set forth by Gustilo and Godina in the 1980s. The purpose of this article is to provide a comprehensive update on the various management aspects of traumatic lower extremity microvascular reconstruction based on the latest evidence, with an examination of recent publications.

Secondary Surgery after Lower Extremity Free Flap Reconstruction.

Microsurgical free tissue transfer may be the only reconstructive option for lower extremity limb salvage. However, the functional and aesthetic results following free tissue transfer after initial salvage may be suboptimal, thus requiring secondary operations to facilitate definitive wound healing and/or refinement. A multi-institutional retrospective cohort study was performed including patients who underwent lower extremity free tissue transfer from January of 2002 to December of 2020. The authors' primary outcome variable was the presence of secondary surgery after free tissue transfer for lower extremity reconstruction. Independent variables (eg, wound cause, flap, donor type, recipient, comorbidities) were collected. Secondary surgery was categorized as (1) procedures for definitive wound closure and (2) refinement procedures. Multivariable logistic regression was performed to determine which variables were independently associated with the outcome. A total of 420 free tissue transfers for lower extremity reconstruction were identified. Secondary surgery was performed in over half (57%) of the patients. Presence of diabetes (OR, 2.0; P = 0.01; 95% CI, 1.2 to 3.5) and use of a latissimus dorsi donor (OR, 2.4; P = 0.037; 95% CI, 1.1 to 5.4) were predictors of wound closure procedures. Fasciocutaneous (OR, 3.6; P < 0.001; 95% CI, 1.8 to 7.2) and myocutaneous (OR, 3.0; P = 0.005; 95% CI, 1.5 to 9.9) flaps were predictors of refinement procedures when compared with muscle-only flaps with skin grafts. The majority of lower extremity free tissue reconstructions required secondary procedures to provide definitive wound closure and/or refinement. Overall, this study provides predictors of secondary surgery that will help formulate patients' expectations of lower extremity limb salvage. Risk, III.

Timing of Unplanned Reoperation After Lower Extremity Free Flap Reconstruction: What Are the Roles of Procedure Indication and Defect Etiology?

Advancements in lower extremity (LE) microsurgery have allowed for the expansion of indications for LE reconstructions. This project aims to better understand the temporal pattern and risk factors associated with LE free flap failure based on the clinical indication. We analyzed all patients undergoing LE free flap reconstruction from the American College of Surgeons National Surgical Quality Improvement Program 2012-2019 prospectively collected data to determine rates and timing of reoperation. Free flaps were stratified by indication, type, and timing of reoperation. Weibull survival models were used to compare rates of takebacks among time intervals. Multivariable logistic regression was used to identify independent predictors for unplanned reoperation. Four hundred seven of LE free flaps were analyzed. There was a 14.5% rate (59/407) of unplanned reoperation within the first 30 postoperative days (PODs) after surgery. When stratified by the indication necessitating reoperation, patients with an underlying vascular indication had the highest rate of reoperation (40.9%). The reoperation rates were significantly different between indications (P < 0.05) The mean daily proportion of patients experiencing reoperation was highest during POD 0 to 2 (1.47% reoperations per day), which dropped significantly during POD 3 to 10 (0.55% per day) and again during POD 11 to 30 (0.28% per day, P < 0.05). African American race as well as malignant, prosthetic/implant, and wound/infectious indications were significant independent predictors for unplanned reoperation. Lower extremity reconstruction is an important reconstructive option for the coverage of a myriad of defects. Understanding the differences between postoperative reoperation timelines among indication subtypes is important for updated flap monitoring protocols, optimizing ERAS pathways, and beginning dangle protocols.

Comparison of Complication Risks Following Lower Extremity Free Flap Reconstruction Based on Seven Pre-Operative Indications: Analysis of the ACS-NSQIP Database

Background: Free tissue transfer is a valuable surgical option for the reconstruction of a myriad of complex lower extremity defects. Currently, there is a paucity of data that examines the risks of complications for each of these unique indications. Methods: Patients undergoing lower extremity free flap reconstruction from the ACS-NSQIP 2011–2019 database were stratified into groups based on the etiology and indication for reconstruction. Rates of major, surgical wound, and medical complications were compared over the first post-operative month. Multivariable logistic regression was used to identify complication predictors. Results: 425 lower extremity free flaps were analyzed. The most common indications for lower extremity free flap reconstruction were wound-related (29%), malignancy (21%), and trauma (17%). Seventeen percent of free flaps had a major post-operative complication, 9% had a surgical wound complication, and 16% had a medical complication. There were no significant differences in major complications between the indications. However, the independent risk factors for major complications varied widely. Those with an indication of malignancy and those who received a musculocutaneous free flap were significantly more likely to have a surgical wound complication compared to the remaining cohort ( p &lt; 0.05). Those requiring free flap reconstruction for orthopedic hardware related concerns as well as those with wound related indications were significantly more likely to have a post-operative medical complication ( p &lt; 0.05). Conclusion: Understanding the unique risk profiles between the various indications and populations of patients undergoing lower extremity free flap reconstruction is critical for providing accurate risk estimations and optimizing post-operative outcomes and monitoring.

Associations of discharge destination and length of stay in lower extremity free flap reconstruction

Patients with lower extremity defects requiring free flap reconstruction often have difficult postoperative courses with prolonged length of stay and need for transfer to a post-acute care facility. The primary aim of this study was to determine associations of preoperative and perioperative variables with length of stay and discharge destination in patients undergoing lower extremity free flap reconstruction. The secondary aim was to determine associations of various complications with their discharge destination. The 2011– 2017 NSQIP database was queried for CPT codes for free flap procedures and ICD-9/ICD-10 codes for lower extremities. Univariate and multivariate analyses were used to determine associations of preoperative and perioperative variables with length of stay and discharge destination in patients undergoing lower extremity free flap reconstruction and associations of complications with their discharge destination. A total of 420 patients were identified who underwent lower extremity reconstruction in 2011–2017. Of 79.8% were discharged home and 21.2% were discharged to destinations other than home. On multivariate analysis, female gender, age > 55, ASA class > 2 and dependent functional status were found to have independent associations with discharge to post-acute care facilities. ASA classification greater than 2, active smoking, and discharge to a post-acute care facility all were independently associated with prolonged length of stay. Increased length of stay and discharge to post-acute care facility are closely associated. Understanding variables that influence length of stay and need for discharge to post-acute care facilities can help identify patients that may be triaged through appropriate interventions and expectation management.

QS27. Surgical Outcomes of Postoperative Intensive Care Unit Versus General Floor Management Following Lower Extremity Free Flap Reconstruction in the Comorbid Chronic Wound Population

Purpose: Free tissue transfer (FTT) lower limb salvage requires costly multidisciplinary care. Traditionally, patients who undergo FTT reconstruction for lower extremity (LE) wounds were admitted to the intensive care unit (ICU) in the immediate postoperative period for close monitoring. During the COVID-19 pandemic, our practice shifted towards admitting FTT patients to the general floor postoperatively instead of the ICU. This is the first study to compare surgical outcomes in patients admitted to the floor versus ICU immediately following free flap reconstruction for chronic LE wounds. Methods: A retrospective review was performed of patients undergoing FTT to LE from 2011 to 2021 by the senior author (K.K.E.). In March 2020, our institution began admitting our free flap patients to the general floor post-operatively. In patients admitted to the floor postoperatively, flap monitoring consisted of an implantable Cook-Swartz Doppler probe for muscle flaps and ViOptix tissue oximetry for fasciocutaneous flaps; clinical exam and hand-held dopplers were not the primary flap monitoring techniques. Patients were divided into two groups depending on whether they went to the ICU or specialty floor in the immediate postoperative period. Primary outcomes were postoperative complications, hospital length of stay (LOS), flap takeback and salvage, and flap success. Statistical significance was set at values of p < 0.05. Results: A total of 255 patients underwent FTT to LE during the 10-year period. Forty-two patients (16.5%) were admitted to the floor postoperatively and 213 patients (83.5%) went to the ICU. Average age and body mass index were 55.8 years and 29.4 kg/m2, respectively. Comorbidities among the two groups were similar, except floor patients had a higher prevalence of diabetes (69.0% vs. 49.3%, p=0.019). Overall microsurgical success rate was 97.3%, which was similar for floor and ICU patients (100% vs. 96.7%, p=0.604). Flap takeback occurred in 3 floor patients (1.2%) and 13 ICU patients (5.1%) (p=0.733). Flap salvage was higher in floor patients, although not statistically significant (7.1% vs. 3.3%, p=0.250). Average hospital LOS did not significantly differ among patients admitted to the floor versus ICU (16.1 vs. 17.7 days, p=0.628). Conclusion: Our findings suggest that postoperative floor admission does not decrease flap success rates and should be considered in patients who undergo FTT to LE reconstruction and are otherwise stable. Efforts should be focused on training floor nurses to use the Cook Doppler and ViOptix devices to monitor flaps. While we expect hospital costs to decrease with floor admission, future studies should focus on the cost impact of postoperative floor management in this patient population.

Limb Elevation by Transcalcaneal Steinmann Pin in Lower Extremity Free Flap Reconstruction.

Lower limb elevation after free flap reconstruction is essential to achieve a satisfactory outcome, avoid pressure (on the flap or over the anastomosis), reduce edema, and prevent venous insufficiency during the first postoperative week. In the upper extremity and head and neck regions, postural measures are easier for the patient. However, achieving the required elevation and immobility for lower extremity free flaps can be a challenge. Different methods have been reported for this purpose, such as simple kickstands, kickstand external fixators,1 and transtibial pins.2,3 In our experience, a Steinmann transcalcaneal pin, described for lower limb traction,4 may offer advantages (Fig. 1).Fig. 1.: Steinmann transcalcaneal pin placed in position. The limb is raised with a Bohler stirrup and a gauze bandage.It is technically simple and rapid to place. Usually far from the surgical field, it can be used in case of tibial reconstruction. It has a low infection rate, and it can be performed under local anesthesia at the bedside if needed. Further advantages of the Steinmann pin are that it allows easier dressing changes in the postoperative period, thereby relieving patients from strict positioning and allowing them to move somewhat while in bed. The pin is placed through the calcaneus, 2 cm below the apex of the inner malleolus and 2 cm from the posterior aspect of the calcaneus in a medial to lateral direction, to avoid the calcaneal branch of the tibial nerve and the retromalleolar neurovascular bundle.5 No radiographic control is needed. The pin is tied with a Bohler stirrup and a gauze bandage to the bed box frame, thus controlling the position of the lower limb, without any pressure on the flap, and allowing correction of the equine foot tendency if needed. In the absence of stirrups, the pin can be fixed directly to a cast. This low-demand mechanical device grants a safer method than simple kickstands, is easier to use than kickstand external fixators, which require multiple pins, and prevents tibial osteomyelitis risk caused by a transtibial pin. [See Figure, Supplemental Digital Content 1, which shows tibia osteomyelitis caused by transtibial pin placement, https://links.lww.com/PRS/F39.] The only precaution to be taken should be to protect the tips of the pin. In conclusion, use of a transcalcaneal Steinmann pin allows for safe and comfortable elevation in lower extremity free flaps. DISCLOSURE The authors declare no conflicts of interest, and did not receive any form of financial or nonfinancial support.

Impact of perioperative vasopressors on lower extremity free flap reconstruction.

Free tissue transfer is a treatment option for soft tissue defects of the lower extremity. For a successful outcome, it is necessary to evaluate the vessel condition and blood flow patency. The administration of a vasopressor could impact the survival rate of free tissue transfer; however, there is a lack of studies on vasopressor use and lower extremity reconstruction. This study aimed to investigate the relationship between the use of a vasopressor and outcomes of free tissue transfer in lower extremity reconstruction. This retrospective, observational study was conducted between March 2010 and February 2019. Data were divided into intraoperative and postoperative variables according to the administration time. Data on patient demographics, risk factors, details of reconstruction, flap outcomes, and duration of intensive care unit (ICU) stay were obtained. Binary logistic regression models were computed to determine the association between flap outcome and vasopressor administration. Of the 338 patients, 186 were administered a vasopressor. Intraoperative and postoperative vasopressor use was not related to the overall complication rate (odds ratio, 1.547; 95% confidence interval, 0.830-2.882; p=.169). Low-intraoperative levels of hemoglobin were associated with the overall complication rate. Postoperative vasopressor administration was associated with prolonged ICU stay. Our results showed that the intraoperative and postoperative use of vasopressors was not significantly associated with the success rate of free flaps. Future studies investigating the relationship between the dose, type, and duration of vasopressors and the complication rate following free tissue transfer are warranted.

The Effect of Variation in Intraoperative Technique on Outcomes in Lower Extremity Free Flap Reconstruction

The Effect of Variation in Intraoperative Technique on Outcomes in Lower Extremity Free Flap Reconstruction

Impact of patients’ gender on microvascular lower extremity reconstruction

The physiological differences between genders have significant implications for health and disease. With regard to microsurgery, results remain elusive as to whether male or female gender is an independent risk factor for free flap reconstruction. This study evaluated the impact of gender on outcomes of lower-extremity free-flap reconstructions. Within 7 years, 358 patients received 393 microvascular lower limb free flap reconstructions. The cases were divided into two groups according to patients’ gender: male vs. female. Retrospective data analysis evaluated patients’ demographics, perioperative details, surgical complications and flap outcomes over a 3-month follow-up period. Major and minor surgical complications, including total and partial flap loss, showed no significant differences between the investigated groups (p>.05). In addition, there was no significant difference with regard to the rate of surgical revision surgery, or the incidence of arterial and venous thrombosis (p>.05). Comparison of different flap types (fasciocutaneous ALT vs. gracilis muscle flaps) and type of anastomosis (end-to-end vs. end-to-side) also revealed no difference in outcomes in respect to gender. In conclusion, gender cannot be regarded as an independent risk factor for free flap reconstructions in patients with lower-extremity defects.

Microvascular free tissue transfer for reconstruction of complex lower extremity trauma: Predictors of complications and flap failure.

Despite advanced wound care techniques, open fractures in the setting of lower extremity trauma remain a challenging pathology, particularly when free tissue transfer is required for coverage. We aimed to evaluate factors associated with flap failure in this setting using a large, heterogeneous patient population. Retrospective review of patients who underwent traumatic lower extremity free flap reconstruction (2002-2019). Demographics wound/vessel injury characteristics, pre and perioperative factors, and flap outcomes were analyzed. One hundred eighty-eight free flaps met inclusion criteria, with 23 partial (12.2%) and 13 total (6.9%) flap failures. Angiography was performed in 87 patients, with arterial injury suffered in 43.1% of those evaluated. Time to flap coverage varied within 3 days (4.5%), 10 days (17.3%), or 30 days of injury (42.7%). In all, 41 (21.8%) subjects suffered from major flap complications, including failure and takebacks. Multivariate regression demonstrated the presence of posterior tibial (PT) artery injury predictive of both flap-failure (Odds ratio [OR]=11.4, p < .015) and major flap complications (OR=12.1, p < .012). Immunocompromised status was also predictive of flap failure (OR=12.6, p < .004) and major complications (OR=11.6, p < .007), while achieving flap coverage within 30 days was protective against flap complications (OR=0.413, p < .049). Defect size, infection, and injury location were not associated with failure. When examining a large, heterogeneous patient cohort, free flap outcomes in the setting of lower extremity open fractures can be influenced by multiple factors. This presence of PT artery injury, flap coverage beyond 30 days of injury, and immunocompromised status appear predictive of flap complications in this context.

P19: THE RELIABILITY OF VENOUS THROMBOEMBOLISM RISK ASSESSMENT TOOLS FOLLOWING FREE FLAP RECONSTRUCTION OF THE LOWER EXTREMITIES

Abstract Introduction The incidence of flap failure in lower extremity reconstruction is significantly higher in the lower extremity compared head, neck and breast reconstruction. The commonest cause of flap failure is venous thrombosis. The aim of this study was to assess the reliability of VTE risk assessment tools in patients with open lower extremity fractures and to assess the ability of such tools to identify patients at risk of developing microvascular venous thrombosis following lower extremity free flap reconstruction. Method A single centre retrospective cohort study was conducted between August 2012-August 2019. All patients were risk assessed using the Department of Health (DoH), Modified Caprini and Padua VTE risk assessment tools. Result 58 patients were included, all were at high risk of DVT according to the DoH (mean score± SD, 3.7±0.93), Caprini (10.2±1.64) and Padua (5.4±0.86) risk assessment tools. All patients received thromboprophylaxis, the incidence of clinical deep venous thrombosis was 0%. Intraclass correlation coefficient demonstrated moderate agreement between the Caprini and DoH (0.73, 95% CI 0.54-0.84, p&amp;lt;0.001), the Caprini and Padua (0.52, 95% CI 0.19-0.72, p&amp;lt;0.001) and the DoH and Padua (0.74, 95% CI 0.57-0.85, p&amp;lt;0.001). Microvascular venous thrombosis occurred in 6 patients, resulting in 2 amputations. There were no significant differences in scores between those with and without venous complications. Conclusion Current VTE risk assessment tools do not identify patients at risk of developing venous complications following lower extremity reconstruction. Further prospective studies are required to optimise risk prediction models and thromboprophylaxis use in this cohort. Take-home message Current VTE risk assessment tools do not identify patients at risk of developing microvascular venous thrombosis following lower limb reconstruction.