INTRODUCTION

The penis is anatomically complex, being involved with both voiding and sexual activity.  Both have significant psychosexual implications for affected patients.  While the functions of sperm and urine transport may be bypassed using modern technology; we are as yet unable to replicate the unique anatomic and biomechanical properties of the penis.  Therefore, current attempts at replacement of an absent or inadequate penis are designed to create an acceptable phallus or penis-like structure.  These reconstructive efforts are referred to as phallic construction or phalloplasty.

The optimal phallus should provide all of the following: 1) both tactile and erogenous sensibility, 2) a neourethra which allows voiding while standing, 3) the capability to permit prosthetic insertion which permits successful vaginal intromission, 4) cosmetically aesthetic acceptability of both the phallus and proposed donor sites, and 5) acceptable phallic growth to adult size in the case of pediatric phalloplasty.  Optimally the surgery should be accomplished in a reproducible single stage with acceptable morbidity.   Modern reconstructive and microsurgical techniques permit us to achieve these aims much of the time.  However, single stage reconstruction eludes us in most cases. 

Phallic construction is one of the most challenging procedures in reconstructive surgery.  At our center we use a multi-disciplinary approach which includes urologists, plastic surgeons, gynecologists, endocrinologists and other experts. The purpose of this review is to discuss the history of phallic construction that has led to current techniques of phalloplasty. These will be briefly outlined in order to address some of the most recent indications for phallic construction, which include the procedure’s use in trauma patients, in patients with congenital anomalies, and in transgender patients.  Discussed are our results in each patient subcategory.

HISTORY

The evolution of phallic construction techniques has paralleled advances in reconstructive surgery.  Initially, random tubed skin flaps were used, which were transferred in tubed delay fashion.  These techniques were supplanted by the use of island and/or musculocutaneous flaps.  With the advent of modern microsurgical techniques, microvascular free transfer flaps have become the state-of-the-art for phallic construction.¹ 

Bogoraz² reported the first successful phallic construction in 1936.  He employed an abdominal tubed flap to construct a phallus, in a case of post-traumatic penile amputation.  This patient ultimately had successful intercourse using a segment of rib cartilage implanted into the phallus as a stiffener, and fathered children after the reconstruction. 

Maltz³ and Gillies and Harrison⁴ are credited with developing the tube within a tube concept which permits a second inner tube to function as a urethra within the outer phallic shaft.  Because the urethra was fashioned from hair-bearing abdominal midline skin, urethral strictures and fistulas were the rule.  Also the unreliable blood supply of the lower abdomen often compromised the flap’s overall viability.  Despite its aesthetic and functional limitations, variations of this abdominal flap remained popular throughout the 1950s and 1960s. In some cases, the inner tube was used for baculum placement to induce rigidity and not for voiding function.

A major step forward in phallic construction was achieved when Noe et al⁵ used the reliable abdominal branch of the external pudendal artery to vascularize the phallus.  Using more reliable vascularity, musculocutaneous flaps were successfully constructed by Orticochea,⁶ Horton et al,⁷ and others.  Although these flaps were more aesthetically pleasing and more reliable, they remained insensate, and often required multiple “touch up” surgeries to achieve an acceptable result.   

Puckett and Montie⁸ performed the first microvascular free transfer flap phalloplasty in 1978.  The seminal work of Gilbert et al⁹ provided erogenous sensation to the phallus via anastomosis of a sensory nerve within the flap to the patient’s pudendal nerve and the radial forearm flap single stage phalloplasty described in 1984 by Chang and Hwang¹⁰ brought this evolving field to the current  position.  Additionally, Lovie et al^11,12 described the use of the ulnar forearm flap for head and neck reconstruction and Gilbert et al¹³ used this flap for phallic construction, which became this center’s procedure of choice.

SURGICAL ADVANCEMENTS

The free forearm flap is the gold standard for the modern phallic construction.  These flaps are ideal from a technical standpoint, as they are malleable, and they remain relatively hairless, thus improving the aesthetic result.  All of the currently employed forearm flap designs share certain common features, including arterial inflow from either the radial or ulnar artery (and venous drainage via basilic, cephalic veins and/or vena comitans), and erogenous sensation provided by either the medial or/and lateral antebrachial cutaneous nerves (Figure 1).  A drawback to this flap is the post-operative appearance of the donor site.  While functional or sensory problems are rare to non-existent within the forearm or hand, the cosmetic appearance may be disturbing to some patients.  The appearance of this site can be improved by resurfacing the forearm with a full thickness skin graft from the groin.  Other phallic construction options have been employed in patients who refuse forearm scars including fibula osseocutaneous flaps^14,15 and metaidoioplasty (plastic surgery to convert a clitoris to a penis),¹⁶ but these are, we feel, clearly sub-optimal choices.

The original Chang & Hwang flap centered the phallic shaft around the radial artery, with the neo-urethra somewhat distant to the principal blood supply.  The Biemer modification of this design centers the neo-urethra over the central portion of the flap, with the phallic shaft created by two skin islands separated from the neo-urethra by de-epithelialized strips.  This modification results in less ischemic injury in the area of the neo-urethra, and allows for extension of the neo-urethra both proximally and distally along the length of the shaft.  This extra length may be critical for a reliable anastomosis to an often foreshortened native urethra.  The main disadvantages of this modification, when based on the radial artery, are that the urethra is centered over the hairiest portion of the forearm and two suture lines result from closure of the skin island around the neo-urethra. 

Classically, the forearm flap was based upon the radial artery but in our hands it is based upon the ulnar artery,¹² since the increased caliber and length of the ulnar artery makes the anastomosis of the vascular pedicle technically more straight forward.  Furthermore, the relatively hairless skin overlying the ulnar aspect of the forearm usually is best suited for urethral and phallic construction.  Over the last 10 years, this center has adopted the ulnar forearm flap which also provides for construction of an integral neoglans (Figure 2).

Preoperative evaluation focuses upon the patient’s general health, particularly from a cardiovascular standpoint.  Heavy smoking with its associated vascular disease is an absolute contraindication to this type of microsurgery.  The vascularity of the non-dominant forearm is assessed with the Allen test, followed by selective upper extremity Doppler sonography or angiography as needed.  To date, we have not had upper extremity complications related to diversion of the ulnar arterial blood flow.

The flap is carefully designed with dimensions specific to the patient’s requirements for phallic and urethral length.  Dissection is carried out superficial to the deep antebrachial fascia, allowing for an extra tissue layer overlying the nerves and muscle tendons of the forearm.  The ulnar artery, basilic and cephalic veins, and medial and lateral antebrachial cutaneous nerves are each meticulously dissected through the forearm and elevated with the flap.  After the flap has been elevated, it is tubularized while still perfused on the forearm.  The central skin island (neo-urethra) is tubularized, after which the outer phallic islands are tubularized.  Finally, the newly constructed glans is transposed over the distal shaft.

The phallus is transferred to the anatomic area of the penis.  The ulnar artery is typically anastomosed to the deep inferior epigastric artery, and the veins are anastomosed to either the deep inferior epigastric vena commitans, or to the saphenous veins.  The urethral anastomosis is performed after vascularity has been restored.  The sensory nerves of the flap are coapted to the dorsal nerves of the penis or clitoris; or in some cases, to the deep internal pudendal nerve.  At the end of the procedure, the patient has a natural appearing phallus (Figure 3), and this appearance is further enhanced by scar remodeling in the subsequent year.  The final step is forearm donor site coverage with thick full-thickness skin grafts – usually harvested from the groins.

SEXUAL FUNCTION OF THE NEOPHALLUS

The goal of achieving reliable phallic rigidity has remained a challenge in the field of phallic construction.  Many options have been attempted with variable results.  Occasionally, the neophallus may possess enough intrinsic stiffness to allow intromission without a prosthetic stiffening device.  The original technique of Bogoraz² involved implantation of rib cartilage in the phallus, and for several years thereafter cartilage or nonvascularized bone were the standard approaches to obtaining phallic rigidity.  The disadvantages of these techniques included warping and resorption of the cartilage/bone with time.  Others¹⁷ used vascularized bone segments incorporated in the phallus to provide rigidity.  Another option has been to create a separate tube for a removable baculum.¹⁷

Prosthetic implants also have been inserted successfully.¹⁸  The phallus usually develops tactile sensitivity between 4 and 9 months postoperatively.  Such sensitivity must be present to protect against pressure necrosis prior to implanting a prosthesis.  Also, the neourethra must have proven to be durable and infection free by this point.  Unlike patients who have suffered traumatic penile amputation, congenital aphallic patients and female to male transgender patients lack corporal bodies in which to seat and anchor the prosthetic device to the pelvis. 

In order to circumvent this problem, we have created the “neotunica,” which is a Gore-Tex (polytetrafluoroethylene) graft, which acts as a sleeve surrounding the actual implant.^18,19  In a transgender patient without corporal remnants, the cylinder is ensheathed in the Gore-Tex sleeve, and the sleeve is then anchored to the periosteum of the ischial tuberosity (inferior pubic ramus) as well as to the pubic symphysis.  If a hydraulic prosthesis is used, the pump is placed in the scrotum.  If corporal remnants are present proximally, they may be opened and used to seat the cylinders.  The neotunica is then used to surround the distal ends of the prosthesis.

The category of prosthesis used is partially dependent on patient preference.  Articulated as well as hydraulic implants have been employed.  At this center we have had good results with the Duraphase^® prosthesis and the AMS 700CX^® prosthesis.  Early in our experience, we tended to place single “rods,” however we now place dual “rods” in the majority of cases.  Two rods provide better rigidity, and are felt to have less potential for erosion. 

INDICATIONS FOR PHALLIC CONSTRUCTION

Trauma

Penile amputation injuries have devastating psychological consequences that usually persist throughout the victim’s lifetime.  In North America, these injuries are fortunately rare.  If the patient presents with the amputated tip of his penis, replantation offers excellent results and can be reviewed further.¹⁹ In many cases the patient does not present with the severed part, and other reconstructive options – including phallic construction– must be entertained.            

Pediatric Phallic Construction

Phallic construction in the prepubertal population continues to be a controversial topic, but should be considered for two broad categories of children.  The first and less controversial category consists of boys who have sustained trauma to the penis.  These boys have already been assigned the male gender.  These patients usually are not candidates for gender reassignment, and phallic construction permits these boys to maintain their male gender identity. 

The second category of patients who may be considered, consists of genetic XY babies who have a congenitally anomalous penis and often genital ambiguity.  These babies may have classic micropenis, aphallia, partial androgen insensitivity or an enzymatic defect such as 5 alpha reductase deficiency.  Also boys with cloacal exstrophy may fall into this category, although cloacal exstrophy is not classified as an intersex condition.  While boys with classic exstrophy/epispadias complex are typically able to function after epispadias repair and chordee correction, the rare patient may have corporal bodies that are inadequate to reconstruct even the most rudimentary penis.  Phallic construction has been successful in some of these patients.²⁰ 

In prior years, many of the patients with micropenis, aphallia and exstrophy were gender-converted in early childhood and reared as girls.  The fact that many such patients have experienced gender dysphoria later attests to the validity of the hypothesis that the genetically male brain is “masculinized” in utero.  The advent and success of modern phallic construction techniques now permits these males to retain their genetic sex, and in rare patients potentially procreate later in life. 

The timing of pediatric phallic construction remains of paramount importance.  The key issue is construction of a phallus which is of appropriate size for a child, but which will reach adult dimensions post-pubertally.  The normal penis is an androgen sensitive organ which grows to adult size during puberty under the influence of dihydrotestosterone.  A forearm flap phallus is not androgen sensitive, and will grow at the rate of other somatic tissues.  Therefore the somatic and genital growth rate must be factored into the equation when calculating relative flap size at any age (Figure 4).²¹  We recommend construction of the neophallus between the ages of 6 and 8 years of age for patients in the pediatric subgroup.

Female-To-Male Transsexualism

Gender dysphoria is a widely recognized psychological condition wherein the patient is of normal phenotype but feels “trapped” in the body of the wrong sex.  The incidence of this condition in the United States is approximately 1:50,000, with a male:female ratio of approximately 6-8:1.²²  Most psychiatrists believe that conversion of adult transsexual patients via psychotherapy back to their biologic sex is nearly impossible.  Many of these patients benefit from hormonal and surgical gender reassignment.  Transgender surgery should be performed only at centers devoted to the complete care of these patients, as psychologic and medical needs require integrated assistance. 

Our center utilizes a multi-disciplinary approach to these patients, utilizing the combined skills of two clinical psychologists, a gynecologist, two urologists and a plastic surgeon.  Patients are evaluated by all members of the committee before acceptance for transgender surgery.  (The Harry Benjamin criteria).²³

Transsexual patients qualifying for phallic construction at our center undergo surgery in multiple stages.  The first stage consists of hysterectomy and oophorectomy (usually via a vaginal approach), vaginectomy, colpocleisis, and urethral lengthening.  The second stage, phallic construction, is as already discussed.  Prosthetic placement is done at a third stage in those select patients that request it.

RESULTS OF PHALLIC CONSTRUCTION

Between 1986 and 1994, 40 patients underwent phallic construction at this center.  Another 34 patients have undergone phallic construction between 1994 and 2001.  Of the first 40 patients, 22 were female to male transgender patients.  As previously mentioned, the introduction of the staged approach, with urethral lengthening, has reduced the incidence of difficult fistulas in this group.  Thirty-four of 40 patients were available for follow-up.  Stricture at the neourethral anastomotic site occurred in 68%, and urethrocutaneous fistulas at the penoscrotal junction in 32%.  At the time of that review in 1993,^24,25 68% of the series were symptom free or required only self-dilation. The modification of staged reconstruction, along with anastamotic covering with a muscle or fascial flap has reduced the overall urethral complication rate to about 30%.²⁵

The results of recent penile prosthesis implantation have been more encouraging than previously reported by this center and others.  We reported 8 patients in whom prosthetic implantation was attempted, 6 (75%) still have prostheses in place.²⁶ Infection necessitated prosthesis removal in 4 patients, of whom two were successfully reimplanted.  Seven of 8 patients have been sexually active using their prostheses.  The infection rate has declined in the past several years secondary to the introduction of perioperative closed suction drains and broad spectrum antibiotics.  We currently have reported approximately 40 patients with only 2 explants in the last 20 patients.²⁷  One was performed for delayed erosion, and the second for vascular compromise of the flap in the immediate post-implant timeframe. 

We have performed phallic construction in the pediatric population,²¹ in 7 prepubertal and 4 adolescent boys, as well as in 5 older boys who had reached 18-24 years of age.  Only one flap failed in the childhood/adolescent group (91% success rate).  All patients who underwent flap nerve coaptation to the pudendal nerve reported return of protective sensation.  All of the adolescents/young adults who underwent phallic construction noted erogenous sensation and the ability to orgasm.  The question of flap growth in the pediatric subgroup is currently under review.

CONCLUSION

While phallic construction remains a challenging aspect of reconstructive surgery, it has evolved tremendously since its inauspicious beginnings in Russia in the 1930s.  Modern phalluses are mostly aesthetically acceptable, durable, and in many cases very satisfying for the patient.  Urethral reconstruction in the neophallus also has improved considerably, with reduction in the number of recorded fistulas and strictures.  The search for an autogenous tissue source to facilitate rigidity continues, but we and others have had significant success thus far with the use of prosthetics in carefully selected patients.  The prepubertal phallic construction continues to stir debate; but we believe that for genetic males, it presents an alternative to gender conversion, and patients must be so counseled.

REFERENCES