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Ventral BMG + Gracilis Muscle Flap (Vanni / Zinman)

Ventral buccal mucosal graft (BMG) urethroplasty with gracilis muscle flap is a specialized reconstructive technique reserved for high-risk, long-segment urethral strictures with a compromised graft bed and poor local vascular supply — where standard urethroplasty is unlikely to succeed.[1][2] The Lahey Hospital group (Zinman, Vanni, and colleagues) reported a selected cohort accumulated over 20 years.

For the foundations gracilis-muscle-flap article (anatomy, harvest principles, multi-organ applications), see Gracilis Flap. For graft material principles, see Buccal Mucosa Graft. For other combined graft + flap urethroplasties, see Combined Dorsal BMG + Ventral Fasciocutaneous Flap (Erickson). For gracilis use in rectourethral fistula repair (Lahey), see the Rectourethral Fistula article.

Rationale​

A free graft (BMG) requires a well-vascularized recipient bed for imbibition and inosculation. In patients with radiation-damaged tissue, prior failed urethroplasty, or extensive periurethral fibrosis, the native corpus spongiosum cannot provide adequate blood supply. The gracilis muscle flap is harvested and transposed to serve as a new vascularized graft bed for the ventral BMG, replacing the deficient spongiosum.[1][2]

Beckenstein 1996 documented epithelial migration after gracilis coverage of a partial urethral defect in one patient with Fournier's gangrene. This case does not establish reliable circumferential urethral regeneration or eliminate the need for a mucosal graft.[4]

Indications​

The percentages below describe overlapping reports from one center, not independent pooled cohorts. Selection depends on the urethral defect and recipient-bed quality.

  • Radiation-induced strictures — the most common etiology, 45–60% of cases.[1][2]
  • Prior failed urethroplasty — 33–45% of patients.[1][2]
  • Post-prostatectomy strictures — 10–23%.[1]
  • Long-segment strictures — mean length 7.6–8.2 cm (range 3.5–15 cm).[1][2]
  • Strictures after transurethral surgery, trauma, or failed hypospadias repair.[1]
  • Patients with prior UroLume stent placement.[1][2]

Surgical Technique​

The procedure as described by Palmer, Zinman, and Vanni:[2]

StepDetail
1. PositioningLithotomy; perineal incision provides access to the urethra
2. Urethral mobilizationVentral urethrotomy through the full length of the stricture; debride or excise diseased / fibrotic spongiosum as needed
3. BMG harvestInner cheek(s) — both cheeks for long strictures; defat and prepare[3]
4. Ventral BMG insetSuture the graft as a ventral onlay patch to healthy urethrotomy margins; place its external surface in contact with the vascularized muscle. This differs from quilting an inlay to the urethral plate
5. Gracilis harvestMobilize the gracilis while identifying and preserving its dominant proximal vascular pedicle; divide distal attachments and secondary pedicles as required for tension-free reach. See the linked flap-anatomy article[2][4]
6. Tunneling and insetTunnel the muscle subcutaneously to the perineum; wrap the gracilis over the ventral BMG as a vascularized graft bed
7. ClosureSecure muscle flap; layered perineal closure over a urethral catheter

Outcomes​

SeriesnMean strictureSuccessMean FUTime to recurrenceRadiation etiologyPrior urethroplastyAUS placement
Palmer 2015[2]208.2 cm (3.5–15)80%40 mo10 mo (2–17)45%45%25%
Rozanski / Vanni 2020[1]307.6 cm (3.5–15)76.7%32 mo (4–92)8 mo (2–17)60%33.3%23.3%

Success was defined by absence of recurrent narrowing preventing passage of a 16-Fr cystoscope in the 2015 report and a 17-Fr cystoscope in 2020. The later cohort expands the earlier experience.[1][2]

Among failures, salvage options included urinary diversion (ileal loop), suprapubic tube placement, endoscopic dilation, or DVIU.[1][2] These selected series support feasibility when reconstructive options are limited; they do not compare the operation directly with diversion or other graft-bed strategies.

Complications​

  • Urinary incontinence is the dominant complication: 23–25% underwent subsequent AUS placement in these cohorts. The uncontrolled studies cannot separate effects of baseline sphincter damage, radiation, previous procedures, and reconstruction.[1][2]
  • Stricture recurrence ~ 20–23%, typically within the first 8–10 months.[1][2]
  • Gracilis donor-site morbidity — generally low. Studies in non-urologic contexts report ~ 11% decrease in hip-adduction strength (not clinically noticed by patients), hypoesthesia in the obturator-nerve distribution in ~ 40%, and thigh-contour deformity in up to 59% of myocutaneous flaps. A small myocutaneous-flap study found associations between necrosis and BMI > 25, smoking, and recipient-site radiation; its rates should not be applied directly to isolated gracilis-muscle urethroplasty.[5][6]

Where It Fits in Urethral Reconstruction​

This technique occupies a specific niche. The AUA 2023 urethral stricture guideline amendment recommends oral mucosa as the first-choice graft material and acknowledges that complex, long, multi-segment strictures may require combined tissue-transfer techniques.[7] Comparative evidence for standard bulbar dorsal versus ventral BMG onlay does not establish outcomes in these high-risk combined reconstructions. In the 2024 GURS survey, 66% of respondents preferred dorsal and 34% ventral placement; only 134 of 350 invited surgeons responded.[8][9][3] However, when the local tissue is too compromised for standard graft take, the gracilis muscle flap can provide a vascularized recipient bed.

Other vascularized-flap options in this setting include the rectus abdominis flap and omental flap (used in robotic posterior urethroplasty).[10] Gracilis is preferred in the perineal approach due to proximity, reliable pedicle, expendability, and ease of harvest with generally limited, but possible, functional donor morbidity.[11][12]

References​

1. Rozanski AT, Vanni AJ. Ventral buccal mucosa graft urethroplasty with gracilis muscle flap for high-risk, long-segment urethral strictures: a 20-year experience. Urology. 2020;140:178-180. doi:10.1016/j.urology.2020.03.008.

2. Palmer DA, Buckley JC, Zinman LN, Vanni AJ. Urethroplasty for high-risk, long-segment urethral strictures with ventral buccal mucosa graft and gracilis muscle flap. J Urol. 2015;193(3):902-905. doi:10.1016/j.juro.2014.09.093.

3. Berg C, Singh A, Hu P, et al. Current trends in the use of buccal grafts during urethroplasty among Society of Genitourinary Reconstructive Surgeons. Urology. 2024;191:139-143. doi:10.1016/j.urology.2024.06.019.

4. Beckenstein M, Smith AA, Dinchman K, Wyatt-Ashmead J, Meland NB. Muscle flap reconstruction aids in urethral regeneration. Ann Plast Surg. 1996;36(6):641-643. doi:10.1097/00000637-199606000-00014.

5. Deutinger M, Kuzbari R, Paternostro-Sluga T, et al. Donor-site morbidity of the gracilis flap. Plast Reconstr Surg. 1995;95(7):1240-1244. doi:10.1097/00006534-199506000-00015.

6. Papadopoulos O, Konofaos P, Georgiou P, et al. Gracilis myocutaneous flap: evaluation of potential risk factors and long-term donor-site morbidity. Microsurgery. 2011;31(6):448-453. doi:10.1002/micr.20899.

7. Wessells H, Morey A, Souter L, Rahimi L, Vanni A. Urethral stricture disease guideline amendment (2023). J Urol. 2023;210(1):64-71. doi:10.1097/JU.0000000000003482.

8. Hassan AA, Soliman AM, Shouman HA, et al. Dorsal- vs ventral-onlay buccal mucosal graft urethroplasty for urethral strictures: a meta-analysis. BJU Int. 2025. doi:10.1111/bju.16811.

9. Shalkamy O, Elatreisy A, Salih E, et al. Erectile and voiding function outcomes after buccal mucosa graft urethroplasty for long-segment bulbar urethral stricture: ventral versus dorsal onlay technique. World J Urol. 2023;41(1):205-210. doi:10.1007/s00345-022-04220-y.

10. Liu W, Shakir N, Zhao LC. Single-port robotic posterior urethroplasty using buccal mucosa grafts: technique and outcomes. Urology. 2022;159:214-221. doi:10.1016/j.urology.2021.07.049.

11. Ryan JA, Gibbons RP, Correa RJ. Urologic use of gracilis muscle flap for nonhealing perineal wounds and fistulas. Urology. 1985;26(5):456-459. doi:10.1016/0090-4295(85)90153-0.

12. Zinman L. Extragenital muscular myocutaneous and fasciocutaneous flaps in urethral reconstruction. Urol Clin North Am. 1997;24(3):683-698. doi:10.1016/s0094-0143(05)70408-0.