Discussion

Reconstruction of pharyngoesophageal defects, especially in patients with large resulting skin defects, continues to be a challenge following aggressive tumour resection. Immediate post-reconstructive considerations include preventing fistulae communicating to deep neck spaces, resulting in bleeding from the great vessels in the neck. Functional considerations include ensuring that the flap lumen is wide enough to prevent stenosis. Donor site morbidity also needs to be considered.

Typical options include a radial forearm free flap, a jejunum flap or an anterolateral thigh flap. Compared to the rectus abdominis and radial forearm free flap, the anterolateral thigh free flap has several advantages for large soft tissue reconstruction, making it a viable alternative.^{Reference Yu, Hanasono, Skoracki, Baumann, Lewin and Weber2,Reference Song, Chen and Song3} The anterolateral thigh free flap is amenable for a two-team harvest, primary donor site closure is readily achieved without skin grafting, and wound complications are limited.

When considering the body habitus of more obese patients, the thickness of the flap means it may additionally be used for the reconstruction of intra-oral defects.^{Reference Kimata, Uchiyama, Ebihara, Yoshizumi, Asai and Saikawa7–Reference Lin, Chen, Kuo and Jeng9} Removal of the excess adipose tissue and deep fascia may aid in reducing flap bulk as needed; however, excessive thinning should be avoided to prevent flap necrosis.

A variety of surgical techniques that utilise the anterolateral thigh free flap have been described for the reconstruction of complicated head and neck defects simultaneously involving the pharynx and external skin. Durmus et al. have previously described the butterfly anterolateral thigh flap for the reconstruction of laryngopharyngeal defects along with external skin resurfacing.^{Reference Durmus, Kakarala, Old, Teknos and Ozer1}

Yu reported the use of a single anterolateral thigh free flap, which was split into two separate skin islands.^{Reference Yu12} One skin island flap was used for the reconstruction of an inner pharyngeal or oesophageal defect, while the other was incorporated in the reconstruction of the external skin and tracheal defects; however, this technique required the availability of at least two cutaneous perforators.^{Reference Tan, Yeh, Shih, Nebres, Yang and Kuo11}

Bianchi et al. described the use of an anterolateral musculocutaneous free flap for hypopharyngeal reconstruction.^{Reference Bianchi, Ferri, Ferrari, Copelli, Boni and Ferri4} The flap was tubed for pharyngeal reconstruction with a thin layer of muscle for peripheral support. One of the primary advantages of this technique includes a decrease in the operative time to 30–40 minutes, compared with the 2–3 hours required for perforator-based flap harvest.

Genden and Jacobson used an elliptical flap design, folding it to form a conical design for the pharyngeal reconstruction.^{Reference Genden and Jacobson5} A portion of the flap was then exteriorised for monitoring purposes.

Although various techniques for free flap monitoring have been described (e.g. pulse oximetry, internal and external Dopplers, colour duplex sonography, thermotropy), the use of cutaneous monitoring paddles allows for reliable, straightforward and easily accessible observation of flap viability. In a review of pharyngoesophageal reconstruction with an anterolateral thigh free flap, Revenaugh et al. found that the incorporation of a suprastomal cutaneous monitoring paddle allowed for reliable clinical observation of flap health, without increasing complications such as speech or swallowing dysfunction.^{Reference Revenaugh, Waters, Scharpf, Knott and Fritz13} Similar results have been reported with radial forearm free flap use, although the amount of forearm skin available and inset geometry restricted the cutaneous portion available for reconstruction; these factors appear to be less limiting with anterolateral thigh free flap harvest given the larger amount of tissue available.^{Reference Akin and Basut14–Reference Urken, Weinberg, Vickery, Buchbinder and Biller16}

Murray et al. utilised a salivary bypass tube both as a template for flap tubing and as intraluminal support for the neopharynx.^{Reference Murray, Gilbert, Vesely, Novak, Zaitlin-Gencher and Clark10} Use of the salivary bypass tube together with surrounding fascia protected healing anastomoses and minimised fistula formation. In order to assess the impact of salivary bypass tubes on fistula and stricture formation, Punthakee et al. carried out a retrospective cohort study of 103 patients who underwent hypopharyngeal free flap reconstruction.^{Reference Punthakee, Zaghi, Nabili, Knott and Blackwell17} These authors demonstrated a significant decrease (p = 0.048) in the fistula rate in patients who received salivary bypass tubes (7.4 per cent) versus those who did not (22.4 per cent); however, no difference was shown in multivariate analysis, likely owing to the large number of patients required to detect a change in outcomes.^{Reference Punthakee, Zaghi, Nabili, Knott and Blackwell17} Despite the small sample size of these studies, salivary bypass tube use appears to play a role in reducing fistula and stricture formation, and its use should be considered in flap reconstruction for hypopharyngeal defects.

In the butterfly technique, one large skin paddle is employed for both inner pharyngeal and outer skin reconstruction, thus eliminating the need for a second flap. One key advantage is that this technique may be applied regardless of the type or number of anterolateral thigh free flap skin perforators. The butterfly technique also allows for multi-layer, watertight closure of the neopharynx, thereby reducing the risk of an anastomotic leak.

Intraluminal salivary bypass tube support also aids in reducing the incidence of wound dehiscence and fistula formation considerably (33 per cent), as reported by Durmus et al., compared to the published series of fistula formation for which the rate is as high as 65 per cent.^{Reference Durmus, Kakarala, Old, Teknos and Ozer1,Reference Murray, Gilbert, Vesely, Novak, Zaitlin-Gencher and Clark10} However, this technique has certain limitations.

As the width of the anterolateral thigh free flap dictates the length of the neopharynx, laryngopharyngeal defects measuring more than 10 cm in length should be excluded for reconstruction with this technique. Additionally, while the exteriorised skin paddle is used as a surrogate to assess the viability of the entirety of the flap, this skin paddle tends to be one of the more vulnerable components, which may complicate clinical decision-making in the setting of flap harm or suspected compromise. Lastly, use of this technique is also limited in significantly larger cutaneous head and neck defects for which exteriorised skin paddles are insufficient to reconstruct the resulting wound following ablation.