This multicenter retrospective study demonstrates that RSAF remains a reliable and effective option for lower extremity reconstruction, with an overall flap succession rate of 96.7% and a mean healing time of 21.5 days. While the majority of flaps survived without major complications, venous congestion was frequently observed (83.3%). Persistent venous congestion occurred in 10% of cases, leading to partial flap necrosis. Factors such as flap width, pedicle length, prolonged operative time, and patient-related variables including BMI and smoking were significantly associated with adverse outcomes. Notably, anatomical site-specific analysis revealed superior long-term survival in flaps used for ankle and lower leg defects (100% at 60 months), whereas heel-based reconstructions exhibited reduced durability (70.8% at 60 months). The findings of this study highlight the favorable outcomes of the RSAF in reconstructing lower limb defects. The overall flap succession rate of 96.7% aligns with prior studies that have demonstrated the reliability of RSAF in managing soft tissue defects of the ankle, heel, and lower leg. The mean wound healing time of 21.5 days and low flap failure rate (3.3%) further support the efficacy of this reconstructive technique [15,16,17].

A subgroup analysis of anatomical site-specific survival rates revealed that ankle and lower leg flaps had excellent long-term viability, with a 100% survival rate at 60 months. However, heel-based flaps demonstrated a decline in survival to 70.8% at 60 months. These findings align with recent research suggesting that the success of reverse sural artery flaps is influenced by their location relative to the ankle joint. Perumal et al. (2019) found that the flap success rate was significantly higher (65%) in patients with injuries at or proximal to the level of the ankle joint, compared with only 42% in patients with injuries distal to the ankle joint [18]. This disparity is likely due to the increased biomechanical stresses and relatively lower perfusion in the heel region, which may predispose flaps to failure. As such, this highlights the importance of considering vascular augmentation techniques in this high-risk area [19,20,21]. Furthermore, previous studies have suggested that preoperative angiography and Doppler assessment can aid in flap planning, particularly in high-risk zones such as the heel [22, 23].

Venous congestion was identified as a significant factor influencing flap success, with 83.3% of cases showing intraoperative congestion. Although most cases experienced only mild-to-moderate congestion, persistent venous congestion led to partial necrosis in 10% of the flaps. This finding is consistent with previous studies that highlight venous congestion as a primary complication in RSAF [24,25,26]. Various strategies have been proposed to reduce venous congestion, including leech therapy and pedicle delay techniques. Furthermore, studies suggest that insufficient pedicle size relative to flap volume may contribute to impaired venous outflow, exacerbating congestion and increasing the risk of flap failure [24]. While the supercharging technique offers additional venous outflow, it introduces microsurgical complexity, whereas the adipofascial technique, which reduces flap volume, provides a simpler alternative with fewer complications [9, 27]. Despite these advancements, venous congestion remains a major challenge, underscoring the importance of addressing vascular insufficiency to improve flap outcomes.

One of the significant observations in this study was the impact of various surgical and patient-related factors on flap viability. Flap failure was associated with a longer pedicle length, increased flap width, prolonged operative, and higher BMI. These findings are consistent with previous literature. Athanaselis et al. reported that flap failures were often linked to technical factors, including ischemia from venous congestion and deep infection, particularly in flaps with wider pedicles or those requiring more extensive dissection [14]. Similarly, Prabhu et al. emphasized that flap size and anatomical site of the defect were among the independent predictors of flap success [28]. Our results support these observations, adding that operative time and patient-specific risk factors such as BMI and smoking status may further compromise flap viability. These insights underscore the importance of careful preoperative planning, including flap dimension optimization and patient risk stratification, to improve outcomes and minimize complications in RSAF procedures.

Operative time emerged as a critical factor influencing flap viability in our study. The mean operative time was significantly longer in the failed flap group (261.5 ± 12.02 min) compared with the successful group (145.86 ± 46.68 min, p = 0.02). This prolonged duration may reflect intraoperative challenges such as difficult dissection, anatomical variation, or patient-specific factors, potentially contributing to increased flap ischemia and compromised outcomes. While operative time is a routinely recorded variable in surgical studies, it is seldom discussed in relation to flap failure specifically. In a large series by Dhamangaonkar and Patankar, the average operative time for RSAF was approximately 121 min, significantly shorter than the mean duration reported in our series [12]. Similarly, Athanaselis et al. documented a mean operative time of 99.03 min (range 83–131 min) [14]. However, neither of these studies provided a direct comparison of operative duration between successful and failed flaps. To our knowledge, this study is among the first to identify a statistically significant difference in operative time between successful and failed RSAFs, highlighting the potential utility of operative duration as a surrogate marker for technical difficulty or intraoperative complications [29]. This finding reinforces the need for surgical efficiency and meticulous planning, particularly in complex cases or in patients with additional risk factors.

In our cohort, 53.3% of patients were smokers, and smoking appeared to be a contributing factor to flap failure, as it was more prevalent among failed cases. This high prevalence may help explain the notably elevated rate of venous congestion observed in our study (83.3%). This observation aligns with previous literature highlighting the detrimental effect of smoking on flap viability. Korompilias et al. (2019) similarly reported complications associated with reverse sural artery flap surgery in patients with comorbidities such as smoking and diabetes. In their series of ten cases involving foot and ankle reconstructions, venous congestion was observed in 40% of patients, leading to partial necrosis in half of these and total flap necrosis in one case. The authors attributed these outcomes to the challenging anatomical location of the defects—70% of which were situated below the ankle—and to the high prevalence of smoking and diabetes in the patient population [30]. The detrimental effects of smoking on microvascular circulation and wound healing are well documented [31,32,33], reinforcing the importance of preoperative smoking cessation counseling for patients undergoing RSAF. Addressing modifiable risk factors such as smoking can play a critical role in improving surgical outcomes and reducing postoperative complications in lower extremity reconstruction.

In our study, we observed that BMI was significantly higher in the failed flap group compared with the successful group, which suggests that elevated BMI may be associated with poorer flap outcomes. However, there remains a gap in the literature regarding the specific impact of elevated BMI on outcomes following post-traumatic lower extremity (LE) microvascular reconstruction. Stanton et al. (2023) addressed this issue in their retrospective review, highlighting the negative impact of elevated BMI on surgical outcomes. Their study found that patients with higher BMI, particularly those in the class III obesity category, were more likely to experience functional limitations, such as nonambulatory status, but did not show significant differences in complication rates. While their study did not focus on flap failure specifically, it suggests that higher BMI could influence postoperative recovery, potentially complicating outcomes due to factors such as delayed wound healing and impaired circulation [34].

Obesity is increasingly recognized as a contributor to microvascular dysfunction, which may impair flap healing. Prior research has shown that elevated BMI is linked to impaired endothelium-dependent vasodilation, reduced capillary density, and decreased tissue oxygenation [35,36,37,38,39]. These effects are believed to result from obesity-related systemic inflammation, endothelial dysfunction, and elevated interstitial pressure, all of which can hinder oxygen delivery at the microcirculatory level [40, 41].

While our data support a correlation between higher BMI and increased risk of flap failure, we acknowledge that the lack of direct physiological measurements of flap perfusion limits our ability to fully understand the underlying pathophysiology. Future prospective studies using these tools could provide deeper insight into how BMI impacts tissue perfusion and help guide risk stratification and surgical planning.

Given these considerations, implementing preoperative strategies to address elevated BMI may enhance flap survival and improve overall surgical outcomes.

This study presents several strengths, including its focus on a well-defined cohort of patients undergoing RSAF surgery, which allowed for a detailed analysis of factors influencing flap success and failure. The large sample size and the inclusion of various patient demographics, as well as detailed intraoperative and postoperative observations, provide valuable insights into the clinical outcomes associated with RSAF procedures. Furthermore, the use of statistical analyses to compare different groups enhances the robustness of the findings. However, the study also has several limitations. First, its retrospective nature may introduce selection bias, as it relies on existing patient records rather than randomized controlled data. While the multicenter design strengthens the external validity of the findings, it may also introduce variability in surgical practices and postoperative care across the centers. The relatively short follow-up period may also restrict the ability to assess long-term outcomes and complications fully. Moreover, due to the limited sample size, multivariate analyses could not be performed to control for overlapping risk factors. Finally, the study primarily evaluated flap survival without addressing functional or aesthetic outcomes, such as return to ambulation or patient-reported scar assessments. Finally, while several factors influencing flap success, such as smoking and BMI, were considered, other potential confounders, such as comorbidities or previous surgeries, were not systematically accounted for, which could affect the results. Despite these limitations, the study provides valuable insights into the factors impacting RSAF success and highlights areas for further research.