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ABI < 0.9 indicate that additional vascular imaging, such as arteriography or computed tomographic
[2]
angiography (CTA), should be obtained . At our center, CTA is used to evaluate for vascular injury and for
preoperative planning as the equipment is readily available and scans can be obtained quickly.

Vascular imaging for patients with lower extremity trauma is typically obtained in one of two contexts. The
first is at the time of initial presentation if a vascular insult is suspected based on the physical exam. If
perfusion is intact, debridement and preliminary orthopedic fixation are performed in a timely manner. The
final reconstructive team may decide the utility of preoperative imaging for surgical planning if one has not
already been obtained [18,19] .

One limitation of CTA is the presence of hardware that may distort or obscure vessel path and patency.
Nonetheless, CTA may provide valuable information when planning microvascular reconstruction
[Figure 1]. When imaging or exam concerns limited perfusion to the leg, planning of free tissue transfer
should consider the principles discussed below.

SURGICAL PRINCIPLES FOR SINGLE-VESSEL FREE FLAP RECONSTRUCTION
General considerations
Reconstruction of the lower leg follows the same principles as reconstruction in other anatomic zones. The
[20]
“reconstructive ladder” and subsequent iterations advise balancing complexity and durability . Especially
in Gustillo III injuries, plans for future reoperations should be considered. If the orthopedic team needs
repeat access to the fracture site or hardware, more robust tissue should be selected instead of the lowest
rung on the reconstructive ladder. In the setting of the significantly traumatized leg with single-vessel distal
perfusion, a surgical plan must also account for perfusion of the transferred tissue in addition to ensuring
continued flow to the foot.

Recipient vessel selection
Selection of recipient vessels depends on several important factors: the location of the defect, the extent of
the zone of injury, exposure of vessels within the wound bed, and known patency of the lower extremity
vessels on CTA [9,21,22] . Single-vessel perfusion to the distal leg or foot precludes an end-to-end anastomosis
using the remaining inflow vessel as this would result in ischemia distal to the flap.

We recommend dissecting a sufficient length of artery and vein(s) (> 4 cm) to allow for ample mobility of
the vessels. All major branches should be preserved until the final anastomotic plan is determined. Once
vessels are prepared, the recipient artery should be clamped to confirm that distal perfusion is adequate.
This can be assessed by examining for a palpable pulse or Doppler signal. Sufficient perfusion may also be
confirmed by retrograde flow from the distal end of a transected vessel; however, this requires division of
the vessel, which is an irreversible step. As venous insufficiency is rarely problematic in these limbs, veins
can be divided distally and reflected proximally to allow for subsequent end-to-end anastomosis.

End-to-end anastomoses using transected or injured vessels
The injured anterior or posterior tibial artery is one option for a recipient vessel. Antegrade or retrograde
flow can potentially be utilized proximal or distal to the area of injury, respectively. The primary advantage
of this recipient is that an end-to-end anastomosis can be performed without disturbing perfusion to the
distal extremity. Should flow through the transected vessel prove inadequate, the uninjured vessel is still
available as a backup. The primary limitation of using the injured vessel is that the recipient vessel is far
more likely to be within the zone of injury and, therefore, may be thrombogenic, friable, and prone to
vasospasm. Proximal dissection (or distal in the instance of retrograde flow) outside the zone of injury is