Page 128 - Read Online

Page 6 of 11 Zhang et al. Plast Aesthet Res 2019;6:30 I http://dx.doi.org/10.20517/2347-9264.2019.040

tissue qualities for corresponding defects: the latissimus dorsi flap provides significant tissue bulk for large
tissue deficits, the neurotized gracilis flap provides potential for restoration of active motion, etc. In a span
of 30 years, microsurgical flaps have become common practice in lower extremity reconstruction. There
remains a disproportionately high rate of complications of free-flaps in microsurgical reconstruction,
with a 14% rate of major complications cited in a retrospective review of over 400 injuries. Independent
risk factors for flap compromise include prolonged operative time, preoperative anemia, steroid use, and
[45]
diabetes .
Other considerations, including selection of recipient vessels, remain of paramount importance. Clinical
orthodoxy favors selection of vessels proximal to the site of injury, given progressive decrease in size of
available source vessels more distal in the leg. However, this orthodoxy has recently been challenged by
select institutions, as selection of recipient vessels distal to the site of injury was recently demonstrated to
be non-inferior in a retrospective review of 312 free-tissue transfers for soft-tissue reconstructions of open
[46]
tibial fractures . This remains a point of contention, but feasibility provides an alternative in the event of
complication precluding more proximal access.

A common paradigm in the reconstruction of lower extremity remains the anatomic subdivision of the leg
into thirds: proximal, middle, and distal. The distal third provides unique reconstructive challenges due
to paucity of local tissue available for local tissue rearrangement, and superficial distribution of structures
requiring coverage. As such, the distal third of the leg manifests the opportunity to put the principles of the
[47]
“reconstructive elevator”, into practice, yet remains plagued by higher rates of complications . Free-flaps
remain the preferred option for reconstruction of substantial deficits in this region. However, comparison
of free-flap coverage demonstrates increase rates of free-flap loss, and complications at the distal third of
lower extremity injuries, when compared to more proximal leg injuries [47,48] . The use of propeller flaps has
arisen as a viable option for soft-tissue coverage when free-tissue transfer is contraindicated, or simply
[49]
not feasible [Figure 2]. Propeller flaps provide substantial soft-tissue for coverage of essential structures
via improved understanding of perfosome distribution without need for microanastomosis in precarious
anatomic regions. Historically, perforator flaps had been thought to require thick cuffs of subcutaneous
tissue to protect the pedicle from kinking, thereby restricting the arc of rotation, and often resulted in
dog-ears at the axis of rotation. As understanding of perfasomes has advanced, including the course and
distribution of these short branching vessels, local pedicled flaps have been used with increasing regularity
for lower extremity reconstruction [43,50] . Particularly in the distal third of the lower extremity, multiple local
flaps including the reverse sural fasciocutaneous flaps can be used with regularity to reconstruct complex
defects, and can be staged as delayed flaps without any question of tissue viability [51,52] . More proximally,
muscle flaps, such as the anterior tibial and soleus flaps, can be translated to cover bony defects following
trauma, further establishing the role of local pedicled flaps in soft-tissue reconstruction of the lower
extremity.

ADVANCES REGARDING IMAGING TECHNOLOGY TO ASSESS LOWER EXTREMITY INJURY
Imaging in the setting of complex injury can be used to not only evaluate the viability of limb salvage,
but also to orient eventual reconstruction via the identification, localization, and qualitative assessment of
potential recipient vessels for purposes of microvascular reconstruction. Hard signs of ischemia, including
hemorrhage, expanding hematoma, and absent distal pulses, are sufficient to prompt operative intervention
to ensure continued perfusion of the distal extremity; in the absence of obvious signs, however, modalities
used for assessment of vascular injury remain variable and institution dependent.

The “gold standard” of evaluating vascular injury remains arteriography, but this modality is limited
by persistent rates of iatrogenic injury, commonly cited at 1%-5%, as well as increased timing of