Keywords
pedicle first - ALT flap harvest - anterior approach - antegrade approach - rapid
harvest
Introduction
First described by Song in 1984, the anterolateral thigh (ALT) flap has proved to
be a reliable workhorse flap for microsurgical reconstruction in the last decade.
Various modifications have been described, and the flap can be harvested as a cutaneous,
fasciocutaneous, musculo fasciocutaneous, adipofascial, chimeric including the tensor
fascia lata (TFL), sensate, and, more recently, supra-thin flap.[1]
[2] With a long pedicle, reliable anatomy, and low donor site morbidity, its use has
been further extended to reconstructing various parts of the body, the head and neck
region being one of them.[3]
[4] The utility of this flap as a chimeric flap helps to reconstruct three-dimensional
defects in the head and neck region. Today ALT flap is one of the most performed free
flap surgeries owing to its versatility and a relatively obscured scar.
The flap is based on either the septocutaneous or the musculocutaneous perforators,
the latter is found in up to 85% of the patients.[5]
[6] Dissecting the intramuscular perforator safely needs good surgical skill which required
long hours of training. In fact, previously, it was considered futile to dissect the
intramuscular perforator as mentioned by Koshima et al in their article.[7]
[8] With the development of new microsurgical instruments and improved optics, it has
become possible to dissect the perforator intramuscularly.[9]
[10] Despite these advances, young microsurgeons often feel hesitant to dissect the perforator
in its intramuscular course, leading to anxiety, frustration, and sub-optimal results.
We believe that dissecting perforator from skin to the source vessel imparts the risk
of damaging the perforator, especially when it follows a long and curved course. It
is often observed that the perforator is damaged during this process which leaves
the surgeon with minor perforators supplying the skin and often with none, resulting
in flap necrosis. To avoid this, we dissect the pedicle in an antegrade manner toward
the skin as this is potentially safe due to the direct visualization of the whole
vessel and the perforators arising from the pedicle into the muscle toward the skin.
Further, the diameter is larger toward the pedicle which makes it easier for identification,
leading to reduced chances of injury. This paper presents our experience with the
pedicle first technique with an emphasis on the surgical technique and tips and tricks
that the author has acquired over years of experience. We also present the results
from our series shedding light on the time of harvest and complications associated
with this technique.
Patients and Methods
A retrospective chart review of all patients undergoing ALT flap reconstruction was
conducted between 2005 and 2020 in which 304 ALT flaps were performed by the pedicle
first technique. All the surgeries were performed by a single surgeon. The patient's
age, sex, and site of defect were recorded as demographic and clinical variables.
Flap harvest time was measured and defined as time taken from skin incision to division
of the pedicle. In addition, the incidence of injury to the skin perforator during
harvest, flap re-exploration rates, and postoperative complications, including the
incidence of flap necrosis, infection, and bleeding were other parameters that were
measured. Statistical analysis was performed by means of Jamovi 1.2.27.0 (Jamovi,
Sydney, Australia). Values were expressed as mean ± standard deviation.
Surgical Technique
Skin markings are initiated by first palpating the groove in between vastus lateralis
and rectus femoris, which denotes the site of the pedicle. The markings span from
2 to 3 cm distal to the inguinal ligament to join the flap markings caudally. The
flap markings are done by marking the skin perforators by hand-held Doppler after
assessing the defect size. An exploratory incision is kept on the anterior aspect
of the thigh beginning 2 to 3 cm caudal to the inguinal ligament to expose the pedicle
in the septum between vastus lateralis and rectus femoris. The incision is then extended
along the medial flap boundaries that are marked preoperatively, thereby elevating
the flap to the intramuscular septum ([Fig. 1]). The vessel is dissected from proximal to distal in the septum between the two
muscles ([Fig. 2]). The pedicle is now visible in its entire length along with the line of perforators
arising from it. Per-operative Doppler can be used at this point of time to look for
all the perforators to the skin thereby confirming the preoperatively marked perforators
to affirm that they are supplying the overlying skin. This also allows us to visualize
all the nearby perforators such as those from anteromedial thigh flap and the TFL
flap to supply a separate island of skin ([Fig. 3]). Often one encounters a separate proximal branch that goes directly into the skin
and can also be used to base the flap.
Fig. 1 Anteromedial exploratory incision.
Fig. 2 Identification of the pedicle.
Fig. 3 Identification of perforators—two in this case.
In our experience, we observed that 95% of the patients were found to have musculocutaneous
perforators. Sometimes, a part of the perforator begins as a septocutaneous perforator
but dips into the muscle before reaching the skin. If a sizeable perforator is found,
it is dissected off the surrounding muscle in an anterograde manner from the descending
branch of the lateral circumflex femoral artery toward the skin paddle. Multiple branches
on the way are clipped or cauterized with bipolar thermy; however, it is preferential
to use clips as heat generated by cautery can cause spasms and damage to the main
pedicle. Coagulation, if done, should be performed slightly away from the source vessel
to prevent its damage. The flaps are raised supra-fascially to begin with, but a cuff
of fascia is preserved as we proceed toward the pedicle. The lateral incision is then
kept raising the flap which can be done again in a supra-fascial manner sparing the
TFL.
In case of injury to the skin perforator or absence of one corresponding to the ALT
flap, other perforators can be used to mark the flap through the same incision. In
case two perforators are found in proximity, a thin strip of muscle between the perforators
is preferably taken to avoid inadvertent damage to the perforators without compromising
postoperative muscle function. If the perforators are observed traversing into the
muscle but not seen to pierce the skin, multiple perforators can be taken along with
some muscle under the flap to ensure good vascularity to the skin. This is technically
easier by the pedicle first technique as we can observe the muscle perforators well
in advance in contrast to when we go from the skin side when the entire flap has the
risk of being elevated without the cutaneous perforator. Whenever a portion of muscle
is taken, we prefer to suture the ends with a negative suction drain to prevent postoperative
hematoma formation.
The flap is then elevated carefully dissecting the nerve away from the pedicle after
ligating the distal end ([Fig. 4]). The vascularity of the skin paddle is checked by scratch test following which
the distal end is ligated, hence completing the flap harvest. A point to be emphasized
here is that since the pedicle is dissected first which aids in visualizing all its
branches and with the aid of per-operative Doppler, it is easier to plan chimeric
flaps such as the TFL and the rectus muscle flap.
Fig. 4 Dissecting the nerve to the vastus lateralis away from the pedicle.
Results
During a period of 15 years between 2005 and December 2020, 304 patients who underwent
ALT flap reconstruction were recorded by means of the medical record of the hospital.
The mean age of the patients in the study was 48 ± 12.5 years (range 22–67 years)
and comprised of 55.2% (n = 168) males. The ALT flap was used most commonly for lower limb reconstruction (57.2%,
n = 174) followed by head and neck reconstruction (28.9%, n = 88) and upper limb reconstruction (13.8%, n = 42).
The mean flap harvest time was observed to be 26 ± 3.2 minutes (range 20–41). During
the flap harvest, iatrogenic injury to the skin perforator occurred in one patient
and none of the flaps had to be discarded intraoperatively. Postoperatively, adverse
events included flap re-exploration (n = 15) and complete flap loss (n = 8). Arterial occlusion occurred in three (20%) flaps, and only one flap was salvaged.
Venous occlusions occurred in 12 flaps (80%), and it was noted that the rate of successful
salvage for venous occlusion (n = 4, 33.3%) was similar to that of arterial occlusion.
Six patients suffered from postoperative bleeding which were either managed conservatively
or taken to the theater where the bleeder was cauterized. Six patients suffered from
infection that was managed effectually by antibiotics based on culture sensitivity
reports. The overall incidence of infection and bleeding is presented in [Table 1]. The patients who suffered from partial necrosis (n = 6) were managed conservatively with dressings and debridement without any need
for additional procedures.
Table 1
Intraoperative findings and postoperative outcomes of patients
|
Mean flap harvest time, minutes
|
26 ± 3.2 (range 20–41)
|
|
Iatrogenic injury to major skin perforator
|
0.3% (n = 1)
|
|
Flap discarded
|
Nil
|
|
Flap re-exploration
|
4.93% (n = 15)
Three arterial
12 venous
|
|
Complete necrosis needing salvage procedure
|
2.67% (n = 8)
Two arterial
Six venous
|
|
Partial necrosis managed conservatively
|
1.97%(n = 6)
|
|
Postoperative bleeding
|
1.97% (n = 6)
|
|
Infection
|
1.97% (n = 6)
|
The mean age in patients whose flaps underwent necrosis was 60.5 ± 4 years. Two of
these patients suffered from cardiac disease. Out of eight patients who suffered from
flap necrosis, ALT flap from the opposite side was the most commonly performed procedure
for reconstruction (n = 3), followed by free latissimus dorsi flap (n = 2). Two other patients were treated by negative pressure wound therapy followed
by grafting, and one was treated with a local flap.
Discussion
The ALT flap is a versatile flap that has become one of the commonest flaps used by
reconstructive microsurgeons. The cutaneous perforators from the pedicle are located
near the midpoint of a line linking the anterior superior iliac spine to the lateral
border of the patella.[11]
[12] A considerable variation is observed in the distribution of the perforators and
in some cases, these may even be absent. The prevalence of this anomaly ranges from
1.37 to 5.4% in the literature.[13] Most of these perforators are musculocutaneous with long and oblique course, which
result in difficult dissection and increase in chances of injury.[14] In our experience, we observed that 95% of the patients had musculocutaneous perforators
and rarely we could find pure septocutaneous perforators. In contrast to septocutaneous
perforators where the dissection is straightforward, musculocutaneous perforators
demand meticulous dissection and failure to do so complicate flap harvesting and can
even lead to intraoperative ALT flap transplantation failure. Even though the skin
may still get its supply from minor perforators, the blood supply is too precarious
to get optimum results. Liu et al reported that intraoperative failure of flap elevation
or transplantation occurred mainly because of perforator injury or mistaken ligation
in 13 out of 1,143 (0.01%) patients.[15] In our study, it was found that in only one patient the perforator was damaged during
flap harvest.
Many authors have given their own protocols to manage injury to perforators. In emergency
cases requiring salvage, conventional remedial management has consisted of using a
contralateral ALT flap or other flap for reconstruction from the same side. In a study
by Liu et al, it was shown that several perforators are located in the ALT region
both in the upper and lower parts.[15] In our experience whenever a sizable perforator is not found or has been accidentally
injured, the patient is managed by taking some part of vastus lateralis underlying
skin paddle which includes minor perforators. Alternatively, the anteromedial thigh
perforator can be marked and used for flap harvest. This prevents immediate abandonment
of the ALT flap.
In the first few cases that we performed, we observed a high incidence of perforator
injury and flap necrosis. Realizing this, exposing the pedicle first through the medial
side and proceeding toward the skin perforators was found to reduce injury to the
perforator. The advantage of this technique over the standard method of harvest lies
in the direct visualization of the skin perforator from the pedicle. Tracing the perforator
from the pedicle is easy as one does not have to blindly guess its course. Further,
because of the larger diameter of the perforator near its origin, its identification
becomes easier.
The mean harvest time was 26 ± 3.2 minutes. This difference is significant when compared
with the mean time (56.2 minutes) taken for flap harvest in the study published by
Chen et al.[16] A study by Lueg et al also reported a mean harvest time of 50 minutes (range 41–75 minutes).[17] Similar to these, other studies report longer harvest time for dissecting musculocutaneous
perforator in comparison to septocutaneous one. We have demonstrated that this technique
is faster while dissecting musculocutaneous perforators. Additionally, the time saved
can reduce the potential postoperative complications due to anesthesia and reduce
the overall costs.[18]
In the postoperative course, 15 patients were re-explored for vascular issues; of
these, eight flaps suffered from complete necrosis, five of them for lower extremity,
two for head and neck, and one for hand reconstruction. Venous occlusions occurred
in 12 flaps, while arterial occlusions occurred in 3 flaps. This was found to be due
to twisting, kinking, or thrombosis at the anastomosis site. We also found that the
rate of successful salvage for venous occlusion (n = 4, 33.3%) was similar to that of arterial occlusion. Our study matches the standards
of published literature stated by Li et al in their systematic literature review in
which 3.3% failure rate was observed in free flaps for head and neck reconstruction.[19]
[20] These patients were managed as opposite side ALT flap in three cases, free latissimus
dorsi flap in two cases, vacuum-assisted closure with grafting in two cases, and local
flap in one. Summary of outcomes of failed cases is given in [Table 2].
Table 2
Summary of patient characteristics in failed cases
|
Age, in years
|
Sex
|
Flap used for
|
Flap failure cause
|
Management
|
Complications
|
|
1.
|
54
|
M
|
Leg defect
|
Arterial thrombosis
|
Opposite side ALT
|
None
|
|
2.
|
43
|
M
|
Foot defect
|
Venous thrombosis
|
Opposite side ALT
|
None
|
|
3.
|
65
|
F
|
Leg defect
|
Venous thrombosis
|
Opposite side ALT
|
None
|
|
4.
|
44
|
M
|
Foot defect
|
Venous thrombosis
|
Debridement after 3 days followed by VAC and grafting
|
None
|
|
5.
|
75
|
F
|
Cheek defect
|
Venous thrombosis
|
Local flap
|
None
|
|
6.
|
72
|
F
|
Hand defect
|
Venous thrombosis
|
Debridement after 5 days followed by VAC and grafting
|
None
|
|
7.
|
65
|
M
|
Head and neck
|
Arterial thrombosis
|
LD flap
|
None
|
|
8.
|
63
|
F
|
Foot defect
|
Venous thrombosis
|
LD flap
|
None
|
Abbreviations: ALT, anterolateral thigh; LD, latissimus dorsi; VAC, vacuum-assisted
closure.
The pedicle first technique is easier to perform in obese patients owing to direct
visualization of the pedicle and the perforators toward the skin. ALT flap was largely
unpopular in the beginning, especially in countries with a significant population
of obese patients. It resulted in increased operative time as well as intra-operative
complications.[21] In our series, we have performed this technique in obese individuals with no difficulty
during dissection; therefore, we believe that this technique is equally useful in
obese patients.
In a few selected patients, it is observed that the perforator size is very thin toward
the skin; in such cases, it is wiser to take a small cuff of muscle around it to prevent
its damage ([Fig. 5]). This makes this technique safer as we begin the dissection where the diameter
of the perforator is large.
Fig. 5 Preserved cuff of muscle around the perforators.
Conclusion
The pedicle first technique makes ALT flap harvest easy, safe, and timesaving for
plastic surgeons to employ this flap in their reconstruction armamentarium. The chances
of injury to the skin perforator are markedly less during dissection, thereby indicating
the superiority of this technique over the conventional one.
