Comparative Histological and Functional Controlled Analysis of Tubularized Incised Plate Urethroplasty With and Without Dorsal Inlay Graft: A Preliminary Experimental Study in Rabbits

Surgical and functional outcomes of Dorsal Inlay Graft urethroplasty in revision vs primary hypospadias repair in the pediatric age

INTRODUCTION

Over the years, Dorsal Inlay Graft (DIG) urethroplasty has gained worldwide acceptance for primary hypospadias repair. However, its safety and effectiveness for revision surgery are yet to be proven.

OBJECTIVE

The aim of the study is to assess and compare complication rates and functional outcomes of DIG surgery in revision versus primary hypospadias repair.

MATERIAL AND METHODS

We carried out a retrospective analysis of data collected from 53 consecutive DIG urethroplasties performed by a single surgeon at our institution. Patients were stratified in two groups - primary repair and redo-urethroplasty. For each group, we recorded standard pre-operative characteristics, surgical technicalities, complication rates and uroflowmetry parameters.

RESULTS

Out of 53 DIG urethroplasties, 21 (39.6 %) where primary and 32 (60.4 %) were re-do. As expected, the two groups differed for median age at surgery: 20 months for primary and 68.5 months for revision surgery (p < 0.001). Additionally, all 21 (100 %) primary interventions were performed with a preputial graft, whereas among revision DIG urethroplasties only 2 (6.3 %) where preputial and 30 (93.8 %) were buccal (p < 0.001). Catheterization time (7 vs 8 days, p = 0.155) and postoperative complication rates (14.3 % vs 9.4 %, p = 0.581) were comparable between the primary and revision surgery group, respectively (all p > .05). Forty-two of the 53 patients underwent uroflowmetry during follow-up. Of these, 19 (63 %) patients presented with abnormal uroflowmetry and 11 (37 %) had equivocal parameters with no difference between the two groups.

DISCUSSION

Dorsal Inlay Graft urethroplasty has long been known to be safe and effective for primary hypospadias repair. On the other hand, data on dorsal inlay graft urethroplasty as a salvage surgery after primary hypospadias repair failure is scarce. Surprisingly, according to our findings, surgical outcomes and complication rates are comparable between primary and revision hypospadias cases. Additionally, our results in the redo group are absolutely encouraging if compared to those reported in the literature for the same subset of patients.

CONCLUSIONS

According to our findings, DIG urethroplasty is a safe and effective option to treat revision hypospadias repair.

Effects of spongioplasty on neourethral function following hypospadias repair: an experimental study in rabbits

Purpose:

Spongioplasty (mobilization and midline approximation of the two branches of the bifid dysplastic distal corpus spongiosum) can form a covering layer for the neourethra to prevent urethrocutaneous fistula in hypospadias repair surgery. However, it remains unclear whether spongioplasty affects neourethral function. The objective of this study was to compare neourethral function after hypospadias repair with and without spongioplasty.

Materials and Methods:

Fourteen congenital hypospadiac New Zealand male rabbits were randomly allocated into two groups, seven animals underwent Duplay hypospadias repair and spongioplasty (experimental group), while seven underwent Duplay surgery alone (control group). Functional differences between groups were assessed by comparing neourethral compliance and flow rate. Two months after surgery, in vivo neourethral compliance was assessed by measuring intraluminal pressure with a digital pressure meter of an isolated neourethral segment, following progressive distension with 1, 2, and 3mL of air. Penises were harvested for uroflowmetry test using a simple device.

Results:

Postoperatively, fistula developed in one and zero rabbits in the control and experimental groups, respectively. Mean pressures tended to be higher in the experimental group than in the control group (82.14 vs. 69.57, 188.43 vs. 143.26, and 244.71 vs. 186.29mmHg for 1, 2, and 3mL of air, respectively), but the difference was not statistically significant. Mean flow rates also did not significantly differ between the experimental and control groups (2.93mL/s vs. 3.31mL/s).

Conclusion:

In this congenital rabbit model, no obvious functional differences were found between reconstructed urethras after hypospadias repair with and without spongioplasty.

Placental membrane grafts for urethral replacement in a rabbit model: a pilot study

PURPOSE

Several graft materials are available for use in the treatment of urethral stricture disease. Placental membrane is being used in a variety of settings as a graft in wound healing and tissue repair. We aim to evaluate the effect of implanting decellularized human placental membrane into rabbit urethras.

METHODS

Dorsal onlay graft urethroplasty using prepared human placental membrane was performed in 10 New Zealand White rabbits (Oryctolagus cuniculus). After 3 months, the rabbits underwent cystourethroscopy to evaluate urethral patency. The rabbits were then euthanized and the urethras examined for pathological findings.

RESULTS

All urethroplasties were performed without complication. There were no observed episodes of urinary retention, infection, or renal failure. Urethral patency was achieved in all rabbits 3 months postoperatively. Urothelial replacement of the placental membrane graft was observed in all rabbits without malignant transformation.

CONCLUSION

Dorsal onlay urethroplasty using decellularized human placental membrane can safely be performed in a rabbit model. This pilot study demonstrated urothelial replacement of human placental membrane in the rabbit urethra without stricture formation. Placental membrane is a promising biomaterial for urethral reconstruction.

Age-related changes in urinary flow following dorsal inlay graft urethroplasty for hypospadias in early childhood: Potential improvement over 11 years of age

INTRODUCTION

One of the goals of hypospadias repair is to create a neourethra with normal urinary stream and normal growth. Several studies have reported that dorsal inlay graft urethroplasty (DIG) has wide indications for various clinical phenotypes of hypospadias, with good short-term outcomes and few complications. However, there have been no reports that evaluated both short-term and long-term functional outcomes using uroflowmetry in patients with DIG.

OBJECTIVE

The aim was to investigate whether uroflowmetry parameters change with time following DIG for hypospadias in early childhood.

MATERIALS AND METHODS

Uroflowmetry parameters after DIG for hypospadias in childhood were retrospectively evaluated and compared between two defined ages at follow-up: 4-6 years and 11-13 years. Maximum urinary flow (Q_max) under the 25th percentile on the Miskolc nomogram was defined as obstruction. To evaluate the shapes of uroflow quantitatively, the flow index (FI) was used. The FI cut-offs for the flow shapes were defined as tower >1.253, plateaus <0.659; bells were between these two values.

RESULTS

Thirty-four patients met the inclusion criteria. The median operative age was 1.8 years (range 1.0-4.9 years). The median follow-up time was 10.3 years (range 7.2-12.3 years). The mean ± SD Q_max at the two follow-up times increased with time, from 9.2 ± 3.7 to 18.8 ± 7.8. The mean ± SD FI changed from 0.53 ± 0.19 to 0.85 ± 0.31. Both Q_max and the FI were significantly improved (p < 0.001, p < 0.001, respectively). There were significantly fewer patients with obstruction evaluated by the Miskolc nomogram at 11-13 years of age (n = 11, 32.4%) than at 4-6 years (n = 31, 91.2%) (p < 0.001). Plateau shapes assessed by the FI were seen in 24 (70.6%) patients at 4-6 years and 10 (29.4%) patients at 11-13 years (Table). The number of patients with plateau shapes was significantly decreased (p = 0.001).

DISCUSSION

Only one report noted long-term outcomes and spontaneous uroflowmetry resolution after tubularized incised plate urethroplasty. The current report is the first to present the short-term and long-term uroflowmetry outcomes after DIG. In addition, the FI was used for the first time to evaluate uroflowmetry after hypospadias repair. It was found that the uroflowmetry parameters improved spontaneously over 11 years of age following DIG for hypospadias in early childhood.

CONCLUSION

Uroflowmetry parameters improved spontaneously over 11 years of age following DIG for hypospadias in early childhood.

Grafted tubularised incised-plate urethroplasty: An objective assessment of outcome with lessons learnt from surgical experience with 263 cases

Objective

Snodgrass urethroplasty remains the preferred technique in primary distal hypospadias but development of meatal stenosis often limits distal extension of the midline incision of the urethral plate (MIUP), which remains a limiting factor in reconstructing an apical neomeatus (NM). We here-in assess the cosmetic and functional outcome with distal extension of the MIUP in grafted tubularised incised-plate urethroplasty (G-TIP) repair.

Patients and methods

This prospective study included the surgical experience of 263 cases of primary hypospadias operated upon between 2012 and 2015. The G-TIP technique included standard steps of Snodgrass urethroplasty, including degloving and harvesting of glans wings, followed by MIUP that was extended distally beyond the margins of the urethral plate (UP) into the glans. The incised bed was grafted with a free preputial skin graft and fixed to the bed with polydioxanone 7-0 suture. The UP was tubularised and the suture line reinforced with a Dartos flap. The urethral catheter was removed at 7–10 days after the repair and the outcome was assessed at follow-up using the Hypospadias Objective Scoring Evaluation (HOSE) system.

Results

An apical NM was achieved in 96% of the patients with a 3.7% incidence of urethrocutaneous fistula. The presence of suture tracks and graft at the margins of the NM were seen in the initial 4% and 5% of cases, respectively. Acceptable cosmetic results, with objective HOSE scores of >14, were achieved in 96% of cases.

Conclusion

The G-TIP repair is a straightforward and feasible technique facilitating reconstruction of an apical NM, with an optimum outcome based on HOSE scoring. However, multicentre data are needed for undertaking comparative analysis and to assess the universal applicability of this technique in primary hypospadias.

Is combined inner preputial inlay graft with tubularized incised plate in hypospadias repair worth doing?

BACKGROUND

It has been noted that after tubularized incised plate urethroplasty (TIP) repair, the final meatal position is glanular but not at the optimum position. Inner preputial inlay graft combined with tubularized incised plate (G-TIP) has been proposed for redo urethroplasty. We extended this indication to be the standard technique for primary hypospadias repair. We conduct this prospective study to obtain a wide, slit-like appearance neomeatus at the optimum position in the glans proper and to judge if hypospadias repair complications differ from TIP repair in the published data in the literature.

PATIENTS AND METHODS

This prospective study included 230 consecutive patients who underwent this technique. The study was conducted from November 2011 to August 2014 for all hypospadias cases to be repaired in a single stage regardless of the width and depth of urethral plate or the glans size and shape. Localization of the meatus was glanular in 13 patients, coronal in 75, distal penile in 112, mid penile in 25 and proximal in five. The urethral plate was incised deeply and extended distally beyond the end of the plate by 3 mm in glans proper. The mucosal graft was harvested from the inner prepuce, inlayed and quilted in the incised urethral plate. The neourethra was created over a urethral catheter in two layers. The vascular dartos flap was mobilized dorsally and moved ventrally to cover the neourethral suture line as a barrier.

RESULTS

The follow-up period ranged from 5 to 36 months. Excellent cosmetic and functional results were achieved in 221 of 230 patients (96.09%). Neither meatal stenosis nor urethral diverticulum were encountered. An excellent glanular position of a wide slit-like neomeatus was achieved using this technique. Nine patients (3.91%) developed urethrocutaneous fistula. Excellent urinary stream was reported by parents.

CONCLUSIONS

Combined inner preputial graft with TIP urethroplasty secures the optimal glanular position of a wide slit-like neomeatus because of extension of the incision beyond the end of the plate, thus optimizing functional and cosmetic outcome with no meatal stenosis.

Urethral plate grafting improves the results of tubularized incised plate urethroplasty in primary hypospadias

OBJECTIVE

We conducted a competitive efficacy trial in order to examine whether grafting the raw area of the urethral plate (UP) with inner preputial skin in children with primary hypospadias (PH) during tubularized incised plate urethroplasty (TIP) improves the results of the operation.

MATERIAL AND METHODS

Fifty consecutive patients with pathology ranging from glanular to proximal penile PH were randomized into two groups, comparable for age and pathology, to be operated on either with TIP or a grafted TIP (G-TIP) procedure. Three patients failed the re-examination protocol, so the TIP group comprised 23 children aged 9.0 months-9.6 years (mean age 3.4 years) and the G-TIP group comprised 24 children, aged 10.0 months-9.4 years (mean 3.5 years). The patients were followed up for a period of 2-5 years (mean 3.2 years).

RESULTS

Within the TIP group, we observed the development of fistula with concomitant neourethral stenosis in two cases (8.7%), stenosis without fistula in four (17.4%), and glans dehiscence in one case (4.35%). Within the G-TIP group there was one case of fistula without stenosis (4.16%), no case of neourethral stenosis, and one case of glans dehiscence (4.16%). Two cases of non-slit-like meatus were observed in the TIP group. The results show that the complications of neourethral stenosis are significantly reduced (p < 0.05) in the G-TIP group, as is the total number of complications and unsatisfactory results. The duration of the TIP operation was 72-110 (mean 92) min, and for the G-TIP 100-136 (mean 115) min. No postoperative symptoms were observed that could be attributed to prolonged anesthesia time.

CONCLUSION

UP grafting with inner preputial skin, when added to the TIP procedure in the treatment of PH, results in a significantly smaller number of unsatisfactory results, and particularly fewer cases of neourethral stenosis. G-TIP can be used as the procedure of choice in PH patients.

Reduced flow after tubularized incised plate urethroplasty--increased fibrogenesis, elastin fiber loss or neither?

PURPOSE

Low urinary flow rates are common after tubularized incised plate urethroplasty but the etiology remains unclear and may be related to low urethral compliance due to abnormal collagen concentrations and/or fewer elastic fibers in the healed urethral plate. We hypothesized that inserting a preputial mucosal graft over the dorsal raw area after the midline incision may avoid scarring and improve urethral compliance.

MATERIALS AND METHODS

Adult rabbits were submitted to tubularized incised plate urethroplasty with or without inlay preputial graft according to a previously described protocol. Tissular concentrations of collagens I, III, IV, VI, VIII and XIII were measured. Histomorphometric analysis was used to quantify elastic fibers in the urethra. Tubularized incised plate urethroplasty with and without inlay preputial graft was compared to normal rabbit urethras (controls).

RESULTS

mRNA concentrations for collagens I, II and XIII were similar between controls and operated rabbits. The proportions between collagens I and III were 1.05, 0.87 and 1.21, respectively, in controls and animals undergoing tubularized incised plate urethroplasty with and without inlay preputial graft. mRNA concentrations for collagen IV and collagens VI/VIII tended to be higher and lower, respectively, in the operated urethras, despite showing statistical significance only for collagen VIII in animals undergoing tubularized incised plate urethroplasty with inlay preputial graft vs controls (p=0.02). The operated animals did not demonstrate a reduced number of elastic fibers in the urethral tissues compared to controls.

CONCLUSIONS

Elastic fiber number and distribution were similar between tubularized incised plate urethroplasty cases and controls, suggesting that decreased concentrations of elastic fibers do not explain the reduced urethral compliance after tubularized incised plate urethroplasty. The raw area determined by the dorsal urethral incision regenerated after standard tubularized incised plate urethroplasty, while cicatrization with fibrosis occurred in correspondence to the grafted areas after tubularized incised plate urethroplasty with inlay preputial graft.

Histological and immunohistochemical changes in the rat oral mucosa used as an autologous urethral graft

PURPOSE

The purpose of this study was to determine the histological and functional (immunohistochemical) changes that take place in oral mucosa grafts implanted in the rat urethra.

METHODS

Urethroplasty was performed in 26 male Wistar rats weighing 250 g. All animals received autologous oral mucosa urethra grafting under general anesthesia. Samples were analyzed 10, 20, 30, 40, 50, 60, 90, and 120 days after surgery using light and scanning electron microscopy and immunofluorescence for the determination of the expression of epithelial markers (pancytokeratin, cytokeratin 1, 4, 13, and filaggrin).

RESULTS

Grafted oral mucosa tissues were subjected to significant histological changes from the beginning with the formation of a well-developed epithelium whose structure was comparable to the native urethra from day 60 of the surgical implant. The immunofluorescence analysis demonstrated that the cytokeratin expression profile tended to mimic the pattern of the native urethra. These data suggest that the oral mucosa is able to efficiently transdifferentiate to the urethral environment.

CONCLUSIONS

The efficient transdifferentiation process of the grafted oral mucosa at both the histological and immunofluorescence levels, and the absence of local complications confirm the clinical usefulness of this type of tissues for the repair of the urethra.