THE OUTCOME OF LONGITUDINAL DORSAL ISLAND FLAP FOR REPAIR OF HYPOSPADIAS IN CIRCUMCISED PATIENTS AND THOSE WITH FAILED PREVIOUS REPAIR

Introduction

H
ypospadias is a congenital disorder of the urethra where the external meatus is located on the ventral penile aspect. It is the second most common birth abnormality of the male reproductive system1. In most cases, the frenulum is entirely missing; however, in rare cases the prepuce could be normal. The prepuce must be preserved early in life and a ritual neonatal circumcision should be avoided to make use of the preputial skin for future repair2.
The multi-factorial etiology of hypospadias is becoming more defined with ongoing investigations. Implicated factors include testosterone biosynthesis defects, 5 alpha-reductase type 2 mutations, androgen receptor mutations, in vitro fertilization (IVF), progesterone administration or abnormalities of the endocrine system3.
The incidence of hypospadias is about 1 in each 250 newborn babies4. The fact that there are over 250 methods of surgical corrections of hypospadias described in the literature indicates that the “hypospadiologists” are still in search for the ideal technique5.
The term ‘hypospadias cripple’ has been applied for individuals with remaining functional complications after multiple attempts of hypospadias repair. Affected men have a heavy burden of psychological problems related to the complications of failed hypospadias repair6. Complications of the initial repair vary widely and include urethro-cutaneous fistula, urethral stricture, glans dehiscence, persistent hypospadias, hair in the urethra, urethral stones, penile shortening, penile curvature, and penile torsion7 .
This study aimed to evaluate the outcome of using longitudinal dorsal island flap (LDIF) for the repair of circumcised patients with proximal, mid and peno-scrotal hypospadias and patients with severe chordee or those with failed previous hypospadias repair.

Patients and methods
This prospective study was done in Basrah General Hospital at urology department from May 2016 till December 2018. Thirty six patients were included in the cohort. Their age ranged from 3 years to 12 years. The included children either were circumcised or had insufficient urethral plates associated with severe chordee or previous repair failure. Six patients were operated upon but excluded from the study because they did not attend regular follow-up.
The inclusion criteria were: Patients with penoscrotal, proximal and mid-shaft hypospadias with history of previous circumcision. Patients with poorly developed urethral plate due to previous failure of hypospadias repair or severe chordee.
The exclusion criteria were: Patients with proximal hypospadias beyond the penoscrotal junction. No complaint patients. Previous failure of the same procedure of (LDIF). Diabetic or immune compromised patients. Patients who are candidates for tubularized incised plate urethroplasty (TIP) repair.
The surgical steps of LDIF start with placing the patient in supine position after having general anesthesia. Prophylactic antibiotics such as ceftriaxone vial 50 mg/kg body weight were given. Stay suture 3/0 vicryl is placed in the glans after insertion of 8 Fr feeding tube to the bladder. Degloving of the penis was done completely and tourniquet was applied intermittently to the base of the penis to help in hemostasis. When thin distal urethra is present, it should be cut back till the level of normal spongiosum-covered urethra. In children with mild chordee correction is assessed by visual assessment after degloving; while in children with the presence of severe chordee, correction is assessed by producing an artificial erection by injection of normal saline in the corpora cavernosa. After correction of chordee, the glans wings are raised and the required length of LDIF is outlined from the dorsal skin in the midline. The flap is harvested from the distal half of the dorsal penile skin; with taking care not to extend too much to the proximal part of dorsal skin. The width of the flap is measured in such a way that it gives a neourethral caliber of at least 8-10 Fr in younger children and 10-12 Fr in older children. The dorsal flap is carefully isolated on its vascular pedicle and dartos attachment, separating it from the two lateral skin flaps. When the dissection is finished, the LDIF is transposed to the ventral site of the penis by making a hole in the center of its mesentery attachment near its base. For the onlay urethroplasty, the flap is sutured to the urethral plate by using 5/0 or 6/0 vicryl sutures starting from the base of the flap around the original meatus and continues distally till reaching to the neomeatus at the glans. Then the distal edge of the flap is sutured to the distal half of the glans after wide glans wings mobilization. For the tubularized repair, when the urethral plate is removed for correction of chordee, the proximal anastomosis is done by spatulation of the tube with the original meatus. An 8 or 10 Fr feeding tube is kept. The lateral flaps are then ventrally transposed to cover the neourethra and glanuloplasty is performed by closing the glans wings over the neourethra using 5/0 vicryl sutures in matress fashion and the penile skin is closed. Dressing was placed over the glans. The feeding tube was kept for 7-14 days. The child was discharged home after 2-3 days and the dressing was changed on the 4th post-operative day. Follow-up of children was carried out at 1 month, 3 months, 6 months and one year postoperatively by assessing the flow rate by uroflowmetry and any complication.

Results
The mean age of the patient was 7.5 year (3-12) years (Table I). The hypospadias site was recognized as mid shaft, proximal shaft and peno-scrotal meatus in 25, 6 and 5 cases respectively (Table II). Twenty four cases of the total 36 had circumcision and had no chordee and were operated upon by onlay LDIF, while in 12 cases, the urethral plate was excised due to the presence of severe chordee or fibrosis and a tubularized LDIF repair was performed (Table III). Excision of the urethral plate successfully corrected the chordee in those patients. The length of the urethral repair was ranged from about 1- 6 cm roughly (Table IV).

Table I: Number of patients in each age group.
Age Number of patients Percentage
3-6 years 10 27.77%
7-9 years 18 50%
10-12 years 8 22.22%

Table II: The site of meatus.
Site of meatus Number of patients Percentage
Midshaft 25 69.55 %
Proximal shaft 6 16.66 %
Penoscrotal 5 13.88 %

Table III: Number and percentage of cases in each group of onlay and tubularized
LDIF repair.
Type of flap Number of cases percentage
Onlay LDIF 24 66.67%
Tubularized LDIF
( Excision of urethral plate was done ) 12 33.33%

Table IV: The average length of the required urethral repair.
Length of the urethra Number of cases Percentage
>2cm 12 33.3%
2-6 cm 22 61.11%
<6 cm 2 5.55%

The success rate was 75% for onlay repair and 58.33% for tubularized repair so the overall mean success rate was 69.44% (fig.1). Complications occurred in 11 patients among all the 36 patients who were operated upon by both onlay or tubularized LDIF, including 6 patients after onlay repair and 5 patients after tubularized repair (Table V).

Figure 1: Success rate for each onlay and tubularized LDIF repair

Table V: Percentage of complications in LDIF repair
Type of repair Number of patients Number of complications Percentage
Onlay repair 24 6 25%
Tubularized repair 12 5 41.66 %
Total 36 11 30.55%

Regarding the flow rate which was done at 3, 6 and 12 months after correction, the mean range of improvement was from 8 ml per second to 11 ml per second (fig.2).

Figure 2: Flow rate ml per second in 3, 6 and 12 months follow-up.

Complications included neourethral stricture which occurred in 1 case in onlay repair group and another 1 case in tubularized repair group. Fistula occurred in 2 cases of onlay repair and 2 cases of tubularized repair. Glans dehiscence in 2 cases of onlay repair and 1 case of tubularized repair. Urethral diverticulum occurred only in 1 case of tubularized repair and neomeatus which occurred in 1 case of onlay repair. No case of any types of LDIF developed flap necrosis, penile shortening or penile curvature (fig.3).

Figure 3: Types and percentage of complication for onlay and tubularized repair

Discussion

In this study, the outcome of the LDIF was reviewed. It is found that correction of hypospadias by using single stage LDIF has good overall success rate with acceptable complication rates. The rate was 30.55% which is comparable with the other studies8-12. The complications of the tubularized longitudinal dorsal island flap repair was more than with onlay LDIF repairs (41.6% vs. 25%). Because of preservation of the urethral plate in most of the recruited cases, the use of the onlay repairs was more than tubularized repair, with better results and fewer rates of complications as was found by a previous researche13. Children with severe chordee or previous surgery requiring excision of the urethral plate may require a 2-stage repair; however, a 60% success rate may be achieved by using tubularized LDIF repair in selected cases as a single stage procedure14,15. In comparison of our results with tunneled buccal mucosa tube grafts for repair of proximal hypospadias, Aivar Bracka and Dino Papeš found in their study of 34 patient that the overall complication in one year follow-up was 32% (11 patients), including fistula in 5, proximal stricture in 4 and meatal stenosis in 2 patients. In the first 10 patients a total of 7 complications (70%) developed but there were only 4 complications in the next 24 patients (16%)16.
In this study, LDIF had more advantages over the transverse preputial flaps repair. This is mainly due to the axial direction of blood supply to the LDIF. In addition, these lateral flaps will provide ventral skin cover over the area of anastomosis17. According to surgical principles, the axial flap has better blood supply than a transverse flap5. Necrosis and ischemia of the neourethra has been reported after transverse preputial island flap repair in about 7% to 10% of cases in other studies6. However, we had no case of necrosis of the flap or distortion in our study. There is high risk of penile torsion when the transverse preputial flap is transposed on the ventral aspect of the penis and is then oriented in a vertical direction for urethroplasty repair9. Due to the original longitudinal orientation of the LDIF, there is no risk of penile rotation or torsion17. Another important advantage of using the LDIF technique is the mesentery of the flap naturally falls in place to cover the neourethral suture lines which helps in decreasing the risk of various complication3,17.
For children with distal and mid penile hypospadias who have a good urethral plate, the TIP repair gives excellent cosmetic and functional results usually and it is still the first choice of repair in such cases. However, hypospadias that have poorly developed urethral plate and more proximal may not be suitable for TIP repair so it is preferred to do LDIF repair. Holland and Smith studied the impact of urethral plate width and depth on the results following TIP repair for distal hypospadias18. They noted that fistulae commonly occur in children with narrow (<8mm width) urethral plates while shallow or flat urethral plates resulted in increased risk of neourethral stenosis. Urethral stricture is one of the most complex and difficult complications to be repaired. Some reports documented abnormal flow curves with obstructive pattern after TIP repair, sometimes even in the absence of an actual stricture19. To overcome the penile torsion that was associated with the original Duckett’s technique, authors modified the new technique by button holing the base of the mesentery for ventral transposition of the flap20. One of the main limitations of using LDIF technique as compared with other island flaps technique, is the limitation in the length of urethra that can be bridged for correction of hypospadias. In this study and by our personal experience of the use of the dorsal flap, we could provide about 2-6 cm length (mean length of LDIF in our study is 32 mm). Because the LDIF is raised from non-hair bearing skin, it has been employed successfully in adolescents and adults also17.
Interestingly, we noted in our study that types of complications after onlay and tubularized technique for repair were different. Glans dehiscence was more common after onlay repair surgery, mainly due to the bulk of tissue over which the glans needed to be sutured. An article reported about 5% of glans dehiscence occur after TIP repair, especially in patients with proximal hypospadias21.
Management of severe proximal hypospadias is challenging and several surgical techniques are suggested as single-stage procedures22-24. Previously they believed that no single surgical procedure that is ideal and the quest for such procedure continues25. There have been a lot of procedures of the two-stage for such severe proximal hypospadias cases in recent years26.
In conclusion, LDIF can be used for single-stage repair of mid, proximal and peno-scrotal hypospadias especially in circumcised children or those with failed previous repairs with good success and a relatively acceptable complication rate regarding onlay flap repair and tubularized flap repair. Onlay repairs had fewer complications than tubularized repairs.