A Novel Approach to Optimize Length Preservation in Cross-Leg Vascular Bridge Flap by AV Shunting

Dear Editor,

Significant lower limb trauma presents formidable reconstructive challenges with compromised vessels, extensive defects, and concurrent conditions like bone exposure, defects, and infection. When locoregional flap options are unfeasible and ipsilateral donor vessels are absent or unfavorable, alternative strategies for limb preservation become necessary. This is particularly important in cases where amputation is culturally or religiously undesirable[1] or when there is a high risk of neuropathic pain or psychological distress.[2] Additionally, limb salvage is prioritized in patients with preserved plantar sensation and young age.

Treatment options include contralateral pedicled cross-leg flaps, free cross-leg flaps, and the cross-leg vascular cable bridge (CLVCB) technique.[1] [3] The CLVCB technique, described by our senior author, utilizes a flow-through tubed radial forearm free flap as a vascular bridge between the contralateral noninjured leg and a second free flap on the defect, preventing excess tension and pedicle kinking and strangulation. The technique enables parallel external fixation between the legs for improved patient comfort between reconstruction stages. The staged approach in this technique allows additional skin coverage using the original radial forearm free flap following the neovascularization of the second flap.

However, in the original CLVCB flap technique, we observe a tendency for partial loss of approximately 3 cm of the vascular bridge due to suboptimal venous drainage distal to the final collateralization of the radial artery and its accompanying venae comitantes. To address this concern and optimize length preservation, we present a novel modification utilizing an arteriovenous (AV) shunt to facilitate adequate venous drainage.

Building upon the previously described CLVCB technique as outlined by Manrique et al,[1] we introduce two areas of modification. Instead of leaving the distal end of the radial artery clipped and the flap suspended as a tube against the calf, an AV shunt is established between the artery and the greater saphenous vein (GSV). The flap adopts a flag-style configuration to accommodate this additional anastomosis. The proximal third of the flap is sutured flatly against the wound, ensuring a smooth alignment to prevent kinking at the proximal anastomosis site from changes in position. Meanwhile, the middle and distal thirds are gently curved to limit the raw surface and facilitate a more secure inset ([Fig. 1]).

Fig. 1 Stepwise demonstration of the technical modification: (1) Elevation of a radial forearm free flap per original description. (2) End-to-end proximal anastomoses to contralateral posterior tibial vessels. (3) Additional distal anastomosis of the radial artery to the proximal greater saphenous vein (GSV). (4) Flap inset in flag configuration: proximal third against the leg, middle and distal thirds gently folded. (5) The second flap was harvested after cross-leg vascular cable bridge (CLVCB) maturation, and the radial forearm flap is now tubed. (6) Proximal anastomoses division postneovascularization, posterior tibial artery reconstructed with GSV segment.

Our modification confers distinct advantages over the previous design. The flat proximal inset prevents kinking at the proximal anastomosis from position changes, ensuring uninterrupted blood flow. Perfusion issues have not been observed despite initial concerns about pedicle kinking between the middle and distal thirds. The AV shunt improves venous drainage and optimizes flap perfusion, particularly in the distal portions, ensuring the viability of the entire vascular bridge. The AV loop can also be divided more proximally, allowing extended reach by providing additional vessel length for the second flap ([Video 1]). The remanent GSV following AV loop division can be readily available for vein graft harvesting as required. While the authors generally opt for direct visual examination of the GSV to assess its patency, caliber, and tissue quality for procedural feasibility, the availability of preoperative ultrasound offers a noninvasive alternative for evaluating GSV patency.

Video 1 Part 1: Immediate postoperative Doppler ultrasound demonstrates side-by-side arrangement and robust radial artery flow. Part 2: One-week follow-up reveals excellent flap perfusion with visible pulsations. Part 3: Flap opened at the second stage, showcasing successful flow in the radial artery and distal greater saphenous vein (GSV) extension, enabling extended vessel reach.

Our modification minimizes potential complications in the original CLVCB technique, improves venous drainage and flap reach, offering improved outcomes in limb reconstruction using the technique.

Publication History

Received: 18 July 2023

Accepted: 28 September 2023

Accepted Manuscript online:
04 October 2023

Article published online:
11 December 2023

• Reference

• 1 Manrique OJ, Bishop SN, Ciudad P. et al. Lower extremity limb salvage with cross leg pedicle flap, cross leg free flap, and cross leg vascular cable bridge flap. J Reconstr Microsurg 2018; 34 (07) 522-529
• 2 Bhuvaneswar CG, Epstein LA, Stern TA. Reactions to amputation: recognition and treatment. Prim Care Companion J Clin Psychiatry 2007; 9 (04) 303-308
• 3 Ciudad P, Escandón JM, Manrique OJ, Llanca L, Reynaga C, Mayer HF. Cross-leg free flaps and cross-leg vascular cable bridge flaps for lower limb salvage: experience before and after COVID-19. Eur J Plast Surg 2023; 1-11