Does the use of arteriovenous loops increase complications rates in posttraumatic microsurgical lower extremity reconstruction?-A matched-pair analysis

One vs. two-stage arteriovenous loops in lower extremity reconstruction with free flaps: Systematic review and metanalysis

BACKGROUND

Arteriovenous loops are one of the main therapeutic alternatives to address the absence of recipient vessels in lower extremity microsurgical reconstruction. However, there is no consensus on whether to perform them in one or two surgical stages. The objective of this work is to determine whether the outcome of lower limb free flaps anastomosed to vascular loops depends on the number of surgical stages.

MATERIALS AND METHODS

A literature review was conducted, following PRISMA guidelines, on vascular loops and free flaps in lower limb. Survival rate, as well as major and minor complications were studied. A forest plot and Pearson's chi-square were used for statistical analysis. Study quality was assessed in duplicate using Methodological Index for Non-Randomized Studies (MINORS) and Joanna Briggs Institute (JBI) tool. This study was registered on PROSPERO.

RESULTS

Thirty-two articles using free flaps anastomosed to vascular loops in lower limb, either one or two-stage, were selected. A total of 296 flaps were included, 52% (n = 154) in one and 48% (n = 142) in two surgical times. No statistically significant differences were found in the survival rate (OR = 1.85, 95% CI 0.62; 5.47, p = .09 and p = .344) or major complications (OR = 0.70, 95% CI 0.31; 1.57, p = .56 and p = .92) of flaps between both groups.

CONCLUSIONS

According to the available evidence, the outcome of free flaps anastomosed to vascular loops in the lower limb does not depend on the number of surgical stages they undergo. Although there is some heterogeneity in the groups studied, the decision on the number of procedures to be performed should be determined by the surgeon, concerning the clinical situation of the patient, as well as to the vascular, bone and soft tissue status of the extremity.

Reliability of Long Vein Grafts for Reconstruction of Massive Wounds

When handling large wounds, zone of injury is a key concept in reconstructive microsurgery, as it pertains to the selection of recipient vessels. Historically, surgeons have avoided placing microvascular anastomosis within widely traumatized, inflamed, or radiated fields. The harvest of vein grafts facilitates reconstruction in complex cases by extending arterial and/or venous pedicle length. To illustrate the utility and fidelity of these techniques, this paper reviews the indications and outcomes for vein grafting in ten consecutive patients at a single tertiary referral center hospital. The case series presented is unique in three aspects. First, there are two cases of successful coaptation of the flap artery to the side of the arterial limb of an arteriovenous loop. Second, there is a large proportion of cases where vein grafts were used to elongate the venous pedicle. In these 10 cases, the mean vein graft length was 37 cm. We observed zero flap failures and zero amputations. Although limited in sample size, these case data support the efficacy and reliability of long segment vein grafting in complex cases in referral centers.

From replantation to transplantation: The evolution of orthoplastic extremity reconstruction

For more than six decades, the use of the operating microscope for extremity surgery has led to remarkable advances in the management of orthopedic trauma, tumors, infections, and congenital differences. The microsurgical reconstructive ladder ascends from basic microsurgical procedures such as a digital artery or nerve repair to more complex procedures such as autologous tissue transplantation. Functional muscle transfers, toe-to-hand transfers, and recently vascularized composite allotransplantation are the highest rungs on this ladder that help restore extremity function. The development of the orthoplastic approach over the last three decades simultaneously integrates the principles and practices of both orthopedic surgery and plastic surgery for optimal care and salvage of extremities. Clinical, anatomic, and basic science research in reconstructive microsurgery has resulted in significant improvements in extremity salvage, reconstruction, and restoration.

Microsurgical Strategies after Free Flap Failure in Soft Tissue Reconstruction of the Lower Extremity: A 17-Year Single-Center Experience

Background: There is no clear consensus on the optimal surgical strategy for providing safe coverage in salvage free flap surgery after total free flap failure. Methods: A retrospective study was conducted to evaluate patients with total failure of the primary free flap in lower extremity reconstruction between 2000 and 2017. Results: In a cohort of 1.016 patients, we identified 43 cases of total flap failure (4.2%). A total of 30 patients received a salvage free flap with a success rate of 83.3% (25/30). One patient received a secondary salvage free flap. Overall limb salvage after primary free flap loss was 83.7% (36/43). Conclusions: Microsurgical management of free flap loss in the lower extremity is challenging and requires a decisive re-evaluation of risk factors and alternative strategies. This should include reconsidering the flap choice with a tendency towards traditional and safe workhorse flaps, a low-threshold switch to different recipient vessels, including arteriovenous (AV) loops, bypasses (especially in case of venous insufficiency) and back-up procedures, such as negative pressure wound therapy or dermal regeneration templates with skin grafting in cases of lower demand and critically ill patients. We derived one suggestion from our previous practice: replacing perforator flaps with axial pattern flaps (“safe workhorses”).

Reconstruction Options for Lower Extremity Traumatic Wounds

The senior author first coined the "orthoplastic" approach to traumatic lower extremity reconstruction, by which multidisciplinary surgeons and specialists work together for optimal patient success. The goals of lower extremity salvage are to optimize limb appearance, restore unrestricted pain-free ambulation, and improve quality of life. Composite traumatic defects require an organized approach, and the reconstructive ladder is used for strategies of varying complexity for repair of soft-tissue wounds. The lower rungs of the ladder include simpler reconstructive options such as the use of skin grafts and local flaps, and the higher rungs represent complex techniques such as free tissue transfer. Although there is no notable difference between muscle and fasciocutaneous/perforator flaps in reconstructive outcomes, there has been a trend toward perforator flaps to minimize donor site morbidity.

Heterogeneous Maturation of Arterio-Venous Fistulas and Loop-Shaped Venous Interposition Grafts: A Histological and 3D Flow Simulation Comparison

Vascular graft maturation is associated with blood flow characteristics, such as velocity, pressure, vorticity, and wall shear stress (WSS). Many studies examined these factors separately. We aimed to examine the remodeling of arterio-venous fistulas (AVFs) and loop-shaped venous interposition grafts, together with 3D flow simulation. Thirty male Wistar rats were randomly and equally divided into sham-operated, AVF, and loop-shaped venous graft (Loop) groups, using the femoral and superficial inferior epigastric vessels for anastomoses. Five weeks after surgery, the vessels were removed for histological evaluation, or plastic castings were made and scanned for 3D flow simulation. Remodeling of AVF and looped grafts was complete in 5 weeks. Histology showed heterogeneous morphology depending on the distribution of intraluminal pressure and WSS. In the Loop group, an asymmetrical WSS distribution coincided with the intima hyperplasia spots. The tunica media was enlarged only when both pressure and WSS were high. The 3D flow simulation correlated with the histological findings, identifying “hotspots” for intimal hyperplasia formation, suggesting a predictive value. These observations can be useful for microvascular research and for quality control in microsurgical training.

Microsurgical Reconstruction of the Lower Extremity in the Elderly

Demand has increased for complex lower-extremity reconstruction in the steadily growing elderly patient group in many highly developed countries. Microsurgery is indispensable for soft tissue reconstruction and osseous consolidation salvaging leg function and preventing amputation, with its devastating consequences. Microvascular reconstruction can be performed successfully in specialized centers with low donor-site morbidity, minimal operative time, and comparably low complication rates. However, this requires thorough multidisciplinary planning, preoperative optimization of risk factors, such as diabetes and malnutrition, and individually adapted intraoperative management. Implementing these principles can reliably restore ambulation and mobility, maintaining autonomy in this population.

Arteriovenous Loops Enable Free Tissue Transfer With Otherwise Inadequate Local Donor and Recipient Vessels

BACKGROUND/AIM

Free flap reconstruction with damaged or diseased vessels is a challenging problem. We describe our case series using an arteriovenous loop or bypass surgery with free flaps for complex defect reconstructions at the lower extremity and the pelvic region.

PATIENTS AND METHODS

In this single-center retrospective cohort study 11 consecutive patients (mean age=73 years, range=53-88 years) were operated on, between June 2016 and August 2018. Patients were reconstructed with free gracilis flaps (n=8), free latissimus dorsi flap (n=1) and chimeric scapular flap (n=1), respectively.

RESULTS

The mean loop length was 30 cm (range=12-40 cm). The loop/bypass revision rate was 27% (3/11), and the overall flap loss rate was 20% (2/10). After a mean follow-up time of 17 months (range=12-24 months), the limb salvage rate was 75% (6/8).

CONCLUSION

We successfully reconstructed complex defects with poor recipient vessels using arteriovenous loops or bypass surgery and free flaps.

Microsurgical Reconstruction of the Lower Extremity

Reconstruction of bony and soft tissue defects of the lower extremity has been revolutionized by the advent of microsurgical tissue transfer. There are numerous options for reconstruction. Possibilities include transfer of soft tissue, composite (bone and soft tissue) tissue, and functional muscle. Many lower extremity reconstructions require staged procedures. Planning is of paramount importance especially in regard to vascular access when multiple free flaps are required. Soft tissue reconstruction of the lower extremity may be accomplished with muscle flaps such as the rectus femoris and latissimus dorsi covered with a skin graft. Fasciocutaneous flaps such as the anterolateral thigh flap may be more appropriate in a staged reconstruction which requires later elevation of the flap. Loss of a significant portion of bone, such as the tibia, can be difficult to manage. Any gap greater than 6 cm is considered a reasonable indication for vascularized bone transfer. The contralateral free fibula is the donor site of choice. Functional reconstruction of the anterior compartment of the leg may be performed with a gracilis muscle transfer, effectively eliminating foot drop and providing soft tissue coverage. Muscle tensioning is critical for effective excursion and dorsiflexion of the foot. Long-term results of microsurgical reconstruction of the lower extremity show good results and reasonable rates of limb salvage.