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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 largest published experience comes from the Lahey Hospital group (Zinman, Vanni, and colleagues), spanning 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]

The muscle also provides an environment that promotes urethral epithelial regeneration — Beckenstein 1996 demonstrated uroepithelial migration across gracilis-covered defects in Fournier's-gangrene reconstruction.[4]

Indications​

  • 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 insetQuilt graft to the opened urethral plate ventrally with absorbable suture. Ventral approach is chosen because dorsal tissues in this population are typically too fibrotic / devascularized to support a graft
5. Gracilis harvestLongitudinal medial-thigh incision; mobilize the gracilis on its dominant proximal vascular pedicle (medial circumflex femoral artery branch) entering ~ 8–10 cm below the pubic tubercle; divide distal attachments and minor pedicles[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)60%33.3%—23.3%

Among failures, salvage options included urinary diversion (ileal loop), suprapubic tube placement, endoscopic dilation, or DVIU.[1][2] Notably, this technique avoids permanent urinary diversion in the majority of patients who would otherwise have limited reconstructive options.

Complications​

  • Urinary incontinence is the dominant complication: 23–25% of patients require AUS placement. This high rate reflects the underlying disease severity (radiation, prior surgery) rather than the technique itself.[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. Flap-necrosis risk factors: BMI > 25, smoking, prior radiation at the recipient site.[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] For standard bulbar strictures, dorsal and ventral BMG onlay yield comparable success rates (~ 88%); the 2024 GURS survey shows ~ 66% of contemporary surgeons favor dorsal placement for routine cases vs ~ 34% ventral.[8][9][3] However, when the local tissue is too compromised for standard graft take, the gracilis muscle flap provides an essential vascularized alternative.

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 without significant functional deficit.[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.