Flap templating considerations in radial forearm phalloplasty—a surgical teaching video overview

Introduction

Gender-affirming phalloplasty is a complex procedure which aligns one’s genital anatomy with their gender identity. The goals of gender-affirming phalloplasty must be individualized to meet each patient’s needs, but the main tenants of a complete phallic reconstruction include creation of an acceptably aesthetic sensate phallus that provides the ability to void while standing and to tolerate an erectile device if desired (1,2). Phalloplasty is being performed with increasing frequency (3), and a wide array of technical variations have been described to achieve an ideal phallus that is tailored to each individual’s needs (1,4,5). Although many donor site options exist, the radial forearm has stood the test of time and remains the most utilized donor site in gender-affirming phalloplasty for several key reasons (6,7):

• It provides enough tissue to construct a phallus of adequate size without excessive bulk;
• Reliable nerve anatomy of the forearm allows for multiple nerve coaptations contributing to optimal sensory outcomes;
• The thin, often hairless, and well vascularized tissue of the ulnar forearm provides the ideal tissue for the penile urethra.

In order to construct an adequately sized phallic shaft and inner urethra, the volume of tissue required for radial forearm phalloplasty is significantly larger than other classically described indications for radial forearm flaps such as oncologic reconstructions of the head and neck. The large dimensions of the radial forearm flap used for phalloplasty push the limits of angiosomes increasing the risk of complications such as partial flap loss (8) and creates significantly greater potential for donor site morbidity (9). For these reasons, flap templating plays a crucial role in the success of the operation and, when done thoughtfully, is a reproducible first step towards minimizing phallic complications and reducing morbidity of the donor forearm.

In this video article, we present a visual overview and description of our technique for radial forearm phalloplasty flap templating for both tube-within-a-tube (TWT) and shaft-only phalloplasty (SOP) constructs. Our aim is to highlight the principles of phalloplasty flap templating that are routinely performed at our institutional phalloplasty program using the “Big Ben” staging method and the rationale for each of these principles (see Video 1).

TWT phalloplasty templating

Patient involvement in the flap templating process allows the patient to both visualize and understand the expected extent of the donor site and also to contribute to decision making regarding penile length. This greatly facilitates shared decision making between patient and surgeon. For this reason, we perform our initial templating in the preoperative area with the patient.

Urethra and urethral extension

The penile urethra is formed from the tissue of the ulnar forearm. It is critical that hair on the urethral component be permanently removed preoperatively. The urethral segment is made 4 cm wide, with a 4 to 4.5 cm long extension proximally that will aid in bringing the penile urethra into a pre pubic position (Figure 1). The length of the proximal urethral extension may vary depending on the staging technique used in phalloplasty. For example, in one-stage phalloplasty or conversion to phalloplasty after metoidioplasty, the urethral extension can be made shorter as the perineal urethra has been lengthened and less distance is needed to connect to the penile urethra.

Figure 1 The recommended dimensions for creation of the urethral extension in a tube-within-a-tube radial forearm phalloplasty. Arrows represent the width of the urethral component as well as the length of the urethral extension with associated measurements.

Between the urethral segment and the phallic shaft, a 1 cm wide strip is de-epithelialized and used in both urethral and shaft closure. This strip can be adjusted to be made more narrow in thinner arms. It is critical to ensure that this strip lies ulnar to the radial artery in order to avoid de-epithelialization directly over the septum where the radial artery perforators enter the flap. There is an additional de-epithelialized segment that we include that extends between the shaft segment and the urethral extension in order to improve perfusion and venous drainage of the urethral extension and capture any additional proximal perforators into the flap design.

Phallic shaft

The phallic shaft is constructed from the tissue of the forearm that lies radial to the de-epithelialized strip. This corresponds to the tissue of the radial and posterior forearm in the distribution of the lateral and posterior antebrachial cutaneous nerves. We prefer to use the deep inferior epigastric artery (DIEA) as recipient vessels in phalloplasty. This permits a shorter pedicle to be taken with the radial forearm flap, allowing for both a longer flap template design and the ability to mark the distal flap template proximal to the radial and ulnar styloid. Preserving this important region of soft tissue coverage over the wrist joint minimizes impact on wrist range of motion. For this reason, the styloid locations are noted and the distal flap margin is determined with the wrist in a flexed position, safeguarding the wrist’s mobility and ensuring adequate soft tissue coverage over the wrist joint.

Flap template length is based on individual preference for penile length, ranging typically from 12 to 15.5 cm (4.5 to 6 inches). We do not make the flap template shorter than 4.5 inches in order to ensure there is a sufficient length of the radial artery septum included to capture an adequate number of perforators to perfuse the entire width of the flap. An additional 0.5 cm is added to the patient’s goal shaft length, as this much is typically lost from the final shaft length due to phallic shaping and inset of the distal urethral meatus. The width at the distal end of the flap is typically 9.5 to 11 cm, and ranges from 12 to 14 cm proximally, adjusted according to forearm thickness and the need to leave a bridge of skin along the ulnar forearm (Figure 2). The radial artery is positioned as centrally within the flap as possible, with at least 5 to 6 cm of the flap positioned ulnar to the radial artery. This ensures that the de-epithelialized segment lies ulnar and away from the radial artery perforators, optimizing flap perfusion and minimizing risk of partial flap loss. The vessels and nerves are accessed through a curvilinear incision extending proximally from the proximal aspect of the phallic shaft marking towards the antecubital fossa.

Figure 2 The recommended dimensions for creation on the phallic shaft in a tube-within-a-tube radial forearm phalloplasty. Arrows represent the shaft dimensions typically utilized.

Lastly the shaft design incorporates a convexity along the flap’s radial edge in order to accommodate expected postoperative swelling and minimize tension at the mid-shaft of the phallus and the associated complications that can occur with excessive tension in that location (10). Finally, care must be taken to preserve a skin bridge along the ulnar forearm to ensure venous and lymphatic drainage from the hand are maintained.

Shaft only phalloplasty templating

De-epithelialized strip and distal urethral meatus

As with the TWT constructs, preoperative patient involvement in the marking process allows for shared decision making during the templating process. In the SOP variant, there is no construction of an inner urethra. However, the tissue from the ulnar forearm is de-epithelialized and rolled inside the shaft to add girth, akin to the urethral segment in the TWT design. This de-epithelialized strip typically measures between 3 to 4 cm in width based on the desired phallic girth. A 3 by 3 cm segment is left with the epithelium intact at the distal aspect of the de-epithelialized strip and is tubularized in order to visually mimic a urethral opening once the flap is shaped (Figure 3).

Figure 3 The recommended dimensions of the tissue that will be used to create the segment that will be deepithelialized and rolled into the flap in a shaft-only radial forearm phalloplasty. Arrows represent the width of the deepithelized strip typically utilized.

Phallic shaft

Flap template measurements for both distal and proximal widths mirror those in the TWT technique to ensure proper phallic structure and size, 9.5 to 11 inches distally and 12 to 14 cm proximally according to forearm thickness. Shaft length again also ranges from 12 to 15.5 cm (4.5 to 6 inches), and an additional 0.5 cm is added to the shaft length to account for expected postoperative length loss of about 0.5 cm from shaping of the distal meatus (Figure 4).

Figure 4 The recommended dimensions for creation of the phallic shaft in a shaft-only radial forearm phalloplasty. Arrows represent the dimensions of the shaft width.

For shaft only constructs, an additional proximal de-epithelialized strip of approximately 2 to 3 mm in width is designed and extends across the entire circumference of the flap template. This strip functions to increase the surface area of the phallus that lies in contact with the flap inset site. The additional anchoring mechanics provided by this segment promote healing and minimize complications such as dehiscence of the phallic base given that there is urethral extension in the shaft only construct that helps anchor the phallus to the mons pubis. The vessels are also accessed through a curvilinear incision extending proximally from the proximal aspect of the phallic shaft marking.

The radial artery is positioned as directly at the midpoint of the flap as possible in order to ensure optimal flap perfusion and minimize cases of partial flap loss. The flap’s position is again carefully planned proximal to the radial and ulnar styloid to minimize impact on wrist mobility and to ensure adequate hand function postoperatively. An ulnar skin bridge is maintained facilitating venous and lymphatic drainage from the hand. Finally, the radial flap edge incorporates a gentle convex curve to minimize mid-shaft tension, ensure a smooth closure, and minimizing complications associated with excessive postoperative swelling.

Summary

• While many tissue donor sites have been described for gender-affirming phalloplasty, the radial forearm is used most commonly due to its size and thickness, reliable nerve anatomy, and urethral outcomes.
• Due to the requirement of a very large flap and the intricacy of the reconstruction, meticulous flap templating is a crucial step in radial forearm phalloplasty to both minimize donor site morbidity and achieve optimal phallic outcomes.
• TWT phalloplasty involves the creation of a hair free neourethral from the ulnar aspect of the flap within the phallic shaft. The template for the neourethra is approximately 4 cm wide and 4 to 4.5 cm longer than the phallic shaft. The shaft length is typically 12 to 15.5 cm long depending on patient preference and 12 to 14 cm wide at the widest part. A 1-cm-wide strip of deepithelized tissue between the shaft and the neourethra accommodates rolling of the neourethra into the shaft.
• Shaft only phalloplasty does not involve the creation of a neourethra, though a 3- to 4-cm-wide strip is rolled into the shaft to add bulk. The shaft dimensions are similar to the TWT construct, with an added 2 to 3 mm proximal deepithelialized strip extending the entire width of the flap which helps to anchor the flap after inset.
• For both TWT and shaft only constructs, preoperative patient involvement in the templating process is important for shared decision-making. Centering the flap over vessels to ensure adequate perfusion, leaving tissue in place over the wrist, and leaving an adequate ulnar skin bridge to facilitate venous and lymphatic drainage from the hand are other important templating considerations that are important for both constructs.

Conclusions

This video article provides a detailed description and visualization of the templating process for radial forearm phalloplasty using a “Big Ben” staging method, including both TWT and SOP designs. By meticulously adhering to these flap templating principles, surgeons can minimize complications and morbidity at both the donor site and the phallic reconstruction.

Acknowledgments

Funding: None.

Footnote

Peer Review File: Available at https://jovs.amegroups.com/article/view/10.21037/jovs-24-9/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jovs.amegroups.com/article/view/10.21037/jovs-24-9/coif). J.U.B. received medico-legal expert fees through Jens Berli Consulting LLC. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient for publication of this study and any accompanying images, and the video. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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