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Stoneburner et al. Plast Aesthet Res 2020;7:13 I http://dx.doi.org/10.20517/2347-9264.2019.028 Page 5 of 18

end-to-end and end-to-side arterial anastomoses, end-to-side anastomoses are generally the preferred
choice for extremities at risk for vascular insufficiency in order to maintain perfusion to the distal leg and
foot [51,52] .

While it was previously thought that only vessels proximal to the injury could be used as recipient vessels
for free flap coverage, it has since been shown that there is no difference in outcomes or reoperation rates
when flaps are anastomosed to vessels distal to the injury [53,54] .

Bone transport with simultaneous soft tissue reconstruction
It is now well-established that early soft tissue coverage of complex lower extremity trauma leads to
successful limb salvage with improved flap success rates and lower rates of infection [55-58] . Thus, the current
practice at most institutions is simultaneous bony fixation and soft tissue coverage. This so-called “fix and
flap” protocol, consisting of radical debridement and skeletal stabilization with immediate or very early free
flap coverage, has resulted in faster union times with lower infection rates [59,60] .

To overcome segmental bone loss and manage later consequences of lower extremity trauma such as
malunion or nonunion, bone transport is often used. By combining free tissue transfer with bone transport,
large segmental and soft tissue defects can be simultaneously treated with great success. Flap coverage
combined with bone transport allows for better limb length restoration by maintaining length from the
start; improving vascularity, which is important for fracture healing; and facilitating bone grafting or other
[61]
subsequent procedures at the docking site .

While classically, the injured limb with critical bony defect was initially treated by debridement and
resection and shortening of bone to allow for primary soft tissue closure, the more recent practice of
combining free tissue transfer with bone transport allows for maintenance of the limb’s original length
and avoids the frequent complications associated with the traditional compression-distraction technique.
The free flap provides healthy vascularized soft tissue, under which distraction osteogenesis can then take
[7]
place .

Few studies have described the effects of distraction on the transferred free tissue and its anastomotic
[62]
pedicle. Jupiter et al. reported that both the free tissue and the native tissue show equal magnitude of
stretch and lengthening without any scar dehiscence after bone transport despite their different tensile
strength and mechanical properties. Many studies have shown that, with major vessel repair in lower
extremity trauma, the anastomotic site tolerates initial distraction process as early as 2-3 days after
surgery [62-64] . However, the outcome of the microvascular anastomosis in these cases has not yet been
reported. It has been demonstrated, however, that immediate distraction osteogenesis with a recent free
[61]
flap has not been found to compromise the flap .

Finally, while placement of pins through the free flap has also been noted to be safe, caution must be taken
when placing the pins so that their anticipated path does not pierce the pedicle [62,65] . Careful planning and
collaboration between the orthopedic surgeon and reconstructive surgeon are needed for these cases to
ensure safe distraction against the pedicle and microvascular anastomosis.

Another potential option for patients needing both soft tissue coverage and assistance with bony growth
is a medial femoral condyle vascularized graft. First described in the 1990s, this method utilizes the highly
vascularized periosteum and either the medial superior genicular or more commonly the descending
genicular artery, due to its length and ease of identification [66-68] . This method usually follows failure of
conventional therapies and has been proven to be efficacious for osteomyelitis, avascular necrosis (AVN),
and nonunions. Specifically, it has been used for the humerus and ulna [69-72] , as well as tibial and femoral