Composite Arteriovenous Radial Conduit Flap for Lower Limb Reconstruction.

In complex lower limb trauma, the healthy recipient vessels can be far from the defect to be reconstructed due to the usually high-energy injury sustained. The use of vein grafts, either directly or in the form of arteriovenous loops, is the usual solution in these cases. In the vein graft donor-depleted patient, other options are required; the composite arteriovenous radial conduit flap may be a useful resort in these situations.

The most critical factor for successful free tissue transfer is the use of healthy vessels as recipients. In complex lower limb trauma, the healthy recipient vessels can be far from the defect to be reconstructed due to the usually high-energy injury sustained. The use of vein grafts, either directly or in the form of arteriovenous (AV) loops, is the usual solution in these cases.[1,2]

Vein grafts are harvested most frequently from the greater and lesser saphenous veins, cephalic, and basilic veins. In the vein graft donor–depleted patient, in whom all possible donor areas either have been already used or are not usable, other options are required. Described in 2001 by Sukkar et al.,[3] the composite AV radial conduit flap may be a useful resort in these situations. The radial artery, along with the radial venae comitantes and the cephalic vein, can be harvested unilaterally or bilaterally and used as a flow-through conduit flap between the reconstructive free flap and the recipient vessels.

CASE REPORT

A 70-year-old male patient presented with an open tibial fracture sustained in a farming environment. The initial treatment was intramedullary bone fixation and a latissimus dorsi free flap after soft-tissue viability delimitation. Two AV loops were used. The first AV loop was connected to the tibioperoneal trunk and thrombosed. The second AV loop was connected to the third portion of the popliteal vessels and used as a recipient. Due to infection, extensive bone debridement and free flap revision were necessary, requiring further vein grafts. The flap survived.

Two months later, the segmental bone defect was reconstructed using a contralateral free fibular flap and a unilateral radial AV conduit free flap to reach the first portion of the popliteal vessels (P1) as recipients (Fig. 1). The proximal radial artery and brachial vein were anastomosed to the P1. The distal radial artery was anastomosed to the peroneal artery, and the peroneal venae comitantes were anastomosed in a double Y configuration to 3 radial venae comitantes and 1 subcutaneous vein. The postoperative course was uneventful (Fig. 2).

Fig. 1.

Intraoperative image of the bone defect. The contralateral fibular flap was transferred using the right radial AV composite conduit flap anastomosed to the first portion of the popliteal vessels, proximal to the anastomoses of the previous latissimus dorsi.

Fig. 2.

Early postoperative picture after external fixation and intramedullary nail removal and exchange for internal fixation with a plate.

DISCUSSION

Vein grafts, either direct or in the form of AV loops, are extensively used in reconstructive microsurgery of the lower limb. Usual donor areas for vein grafts could be no longer available in a patient. Although it has been recommended that the vessels distal to the zone of injury be used, the necessary 180-degree turn of the veins carries a definite risk of kinking.[4] It is generally accepted that healthy proximal vessels are preferable. Arterial grafts have been described, although they have limitations in dimensions and available donor options.[5]

The composite AV radial conduit flap was described by Sukkar et al. in 2001.[3] It includes the radial artery and its venae comitantes as a flow-through conduit. In average, 20–25 cm of radial AV bundle can be harvested in an adult, per side, making up to 50-cm-long constructs if taken bilaterally and spliced. The distal radial artery is a good caliber match for most reconstructive free flaps. If the cephalic vein is not scarred, it can also be incorporated to the bundle, expanding the possibilities for venous outflow of the flap. In cases when this vein is not usable, the distal venae comitantes of the radial artery are small in caliber for most reconstructive flaps, and “Y-shaped” anastomoses should be performed.[6]

The descending branch of the lateral circumflex femoral artery bundle has also been described,[7] although it is shorter than the radial bundle. The contralateral posterior tibial, anterior tibial, or the peroneal vascular bundles could theoretically be used for this same purpose, allowing longer segments. The use of the posterior tibial bundle was reported in a complex ectopic foot replantation case.[8]

Vein grafts are very sensitive to infection. The composite AV conduit flaps may be more resilient and less sensitive to septic complications because the vessel walls are surrounded by vascularized periadventitial tissues that may confer some protection. Flow-through flaps have been described for simultaneous soft tissues and arterial reconstruction of the limbs or for complex double piggyback constructs, especially in head and neck.[9] The composite flap described herein should not be considered a flow-through flap.