Two-stage Hypospadias Repair With Buccal Mucosa Tube Grafts For Severe Hypospadias:Clinical Evaluation And Long-term Follow-up And Histopathological Evaluation Of Urethroplasty With Buccal Mucosa Graft:An Experimental Study In Rabbits

Part 1Two-stage hypospadias repair with buccal mucosa tube grafts for severe hypospadias:clinical evaluation and long-term follow-upObjective:To report the clinical outcomes of a single surgeon's experience with the hypospadias repair using two-stage buccul mucosa tube grafts for both severe primary and revision hypospadias with long-term follow-up;To evaluate the long term clinical outcome of the patients with genital shape,urethral morphology and postoperative urethral function;To identify risk factors for the surgical repair of severe hypospadias by retrospectively analyzing the patient who received hypospadias repair(by SBMTG)in our center with appropriate statistical methods.In order to improve the success rate of hypospadias repair in our hospital,we should establish and improve the standardization system of objective evaluation of the morphology and function of hypospadias with plastic surgery specialty.Continuous re-evaluation and assessment of outcome may have a major impact on future clinical practice.Materials and methods:From January 2011 to December 2015,objective outcome data of the patients who underwent SBMTG for severe hypospadias repair is analyzed retrospectively.The urethroplasty procedure included penile urethra reconstruction with the buccal mucosa tube grafts in the first stage,anastomosis of the unobstructed urethra in the second stage and a scrotal fascio-cutaneous flap transferred to resurface the reconstructed urethra and cystostomy.The 'HOSE' questionnaire,flowmetryresults,spray pattern analyses,ultrasoundurethrogram in combination with other questionnaire data were obtained to assess cosmetic and sexual results and evaluate the long-term results of the SBMTG technique.Potential risk factorsfor the surgicalrepair of severe hypospadias by retrospectively analyzingobjective outcomes were identified with appropriate statistical methods.Results:Of 261 patients,183 patients were obtained to follow up(70.1%follow up rate)with an average follow up of 24 months(range 6-79).102 patients(55.7%)were acquired long-term follow up more than 24 months.The average age at the latest clinical follow up was 13 years old(range 2.3-49).The surgical treatments of 133 patients(72.7%)wereconsidered to be successful(without complication).In the univariate analysis,times of repair(p=0.018)were statistically related with the outcome of surgery,and in the multivariate Logistic analysis,times of repair(adjusted OR 2.54,p=0.020)wereidentified as risk factors for unsuccessful outcomes as well.Post-operative evaluation and assessment of clinical outcome:the average HOSE score was 14.3±1.6.HOSE assessment is good,with 82.5%(152 cases)of patients scoring 14 or over.It was statistically related that the patients who received the first stage operation were younger,and the higher the possibility of satisfaction(p=0.001).In the study,postoperative flowmetry was available for 58 cases(older than 7 years old),and flows with fistula or other complications were not recorded.31 cases had lower urinary symptoms for some extent like spraying and incomplete emptying.The average maximum flow(Qmax)in the study was 15.09 ± 3.88ml/s(range 6.2-25.5 ml/s).The uroflow data were plotted on the Siroky normograms,with 43 patients(74.1%)having uroflow rates above2×SD from the control mean and without lower urinary symptoms.25 patients(older than 16 years old)reported their sexual function with a sexual function questionnaire and IIEF-5:25cases(66.7%)were satisfied of the overall sexual evaluation,and 68%patient complainedejaculationproblems.12 patients who had experienced sexual intercourse reported that fifty percent of patients had a normal erectile function(IIEF-5>22;n = 6/12).Conclusion:(1)The two-stage hypospadias repair with buccal mucosa tube graftswas a saft,reliable and durable procedure for severe hypospadias offering low morbidity and good cosmetic and functional results.(2)In the first stage,the penis was adequately straightening and ventral chordee was completely excised,and a suitable lengthof the buccal mucosa was harvested as a tube graft to prefabricate the penile urethral.The use of scrotal flaps seems to contribute to a good vascularized waterproof cover in the second stage.(3)The successful rate of the SBMTG procedure was 72.7%with the long term follow up.It was statistically related that the patients who received the first stage operation were younger,and the higher the possibility of satisfaction.(4)The statistic result suggests that the times of repair was the independent risk factor for surgical complications of SBMTG for severe hypospadias repair.When the patient had been received unsuccessful repair,the risk has a 2.54-fold increase.(5)The post-operative urethral function and sexual function seem to be relative normal but would have preferred a larger sample of patients and an even longer follow-up.(6)Post-operative ultrasound urethrogram for the characterization of reconstructive urethral is safe and feasible.In conclude,the USUG,HOSE score,urine flow rate(Qmax),urinary function and sexual function evaluationquestionnaire could be used as objective indicators of postoperative follow-up in our hospital.Part 2Histopathological evaluation of urethroplasty with buccal mucosa graft:an experimental study in rabbitsObjective:To histologically evaluate the integration process of the buccal mucosa onlay graft applied on the dorsal corpora cavernosa for one stage urethroplasty in an experimental study in rabbits,as well as to speculate potential mechanism of the survival of the buccal mucosa and the impact of the tunica and corpus cavernos.Materials and methods:We succeeded in establishing the rabbit model of congenital hypospadias.This study included a total of 20 New Zealand rabbit model of hypospadias(penile type and scrotal-perineal type)aged 4 months.After releasing the chordee of the dorsal corpora cavernosa,the urethral defect was created by applying buccal mucosa onlay graft for the penile urethral reconstruction.The animals were sacrificed at 1,2,4,12,24 and 36 weeks post surgery and their genitals were subjected to morphological observation and histological assessment with hematoxyiin-eosin(HE),Masson and Stirus staining.Results:(1)22 rabbit models of congenital hypospadias were established successfully including glans type(1),penile type(15)and scrotal-perineal type(6).(2)The buccal mucosa graft showed complete uptake in all animalsthe location of the graft was macroscopically identifiable,demonstrating its good integration.The typical squamous epithelium of buccal mucosa was observed and might still have secretory function.One week after surgery the buccal mucosa graft area represented an acute inflammatory reaction,and it was difficult to identify the cell level of subepithelial layer and the tunica.We realized that two weeks after surgery the epithelial layer was getting thick,few neovascularity and young fibroblasts were observed in the subepithelial layer.Four weeks after buccal mucosa grafting,gradual arrangement of epithelial layerwas visible,the young fibroblasts were increasing and areas of mature collagen could be seen.Extensive neovascularity was evident in the subepithelial layer.The typical squamous epithelium of buccal mucosa and minimal inflammatory cell infiltration in the subepithelial tissues were observed at the grafted mucosa twelve weeks after surgery.It was distinguishable to identify the cell level of subepithelial layer and the tunica of corpus cavernos.Twenty-four to thirty-six weeks after surgery,the epithelial layer was well integrated with adjacenturethral mucosa.Accentuated fibrosis was noticed with extensive mature collagenand without signs of inflammation and scarproliferationof the grafts.Conclusion:(1)The animal model of congenital hypospadias in rabbits could be established using Finasteride Tablets in a dosage of 10 mg · kg-1 · d-1 for consecutive from 7 days.It was feasible to use the animal model to carry out the experimental study of buccal mucosa grafts.(2)The typical squamous epithelium of buccal mucosa was observed after grafting and might still have secretory function.Extensive neovascularity was evident in the subepithelial layer,and the survival of the grafted mucosa was obtained four weeks after surgery.The minimal inflammatory cell infiltrations in the subepithelial tissues were observed at the grafted mucosa twelve weeks after surgery.It was distinguishable to identify the cell level of subepithelial layer and the tunicaalbuginea of corpus cavernos.After 24 weeks,accentuated fibrosis was noticed with extensive mature collagenand without signs of inflammation and scarproliferationof the grafts.It was the evidence that the second stage of the urethral anastomosis could be accomplished the grafted mucosa 24 weeks after the first stage operation in the clinical practice.(3)Buccal mucosa grafting(after 12 weeks)had no obvious limitation effect on the tunicaalbuginea and the corpus cavernos development.