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Muscle-Sparing Urethroplasty

Muscle-sparing urethroplasty encompasses two related but distinct concepts: (1) the Barbagli muscle- and nerve-sparing bulbar urethroplasty (preserving the bulbospongiosus muscle during standard bulbar urethroplasty) and (2) the Kulkarni one-sided dorsolateral dissection technique (preserving the contralateral bulbospongiosus muscle, neurovascular bundle, and central tendon). Evidence on whether bulbospongiosus muscle sparing improves functional outcomes is conflicting — some studies show significant reductions in postvoid dribbling and ejaculatory dysfunction, while two multi-institutional comparative analyses show no significant benefit.[1][2][3][4]

For non-transecting anastomotic alternatives that also preserve corporal vascular supply, see Non-Transecting Bulbar Urethroplasty and Jordan Vessel-Sparing EPA. For augmented variants, see Augmented Anastomotic Urethroplasty. For graft details, see Buccal Mucosa Graft.

Anatomy and Rationale​

The bulbospongiosus (BS) muscle is a paired, striated muscle that envelops the ventral surface of the bulbar urethra and corpus spongiosum. It is innervated by the perineal branch of the pudendal nerve and plays a critical role in:[4][5]

  • Urinary expulsion — compresses the bulbar urethra during the final phase of micturition to expel residual urine
  • Ejaculation — rhythmic contraction propels semen through the urethra
  • Erection support — contributes to penile rigidity by compressing the bulb of the penis

In standard bulbar urethroplasty, the BS muscle is divided in the midline raphe to expose the underlying corpus spongiosum. The concern is that midline division damages the muscle's innervation and vascularization, leading to postoperative postvoid dribbling (PVD) and ejaculatory dysfunction (EjD).[3][4]

Technique 1 — Barbagli Muscle- and Nerve-Sparing Bulbar Urethroplasty (2008)​

First described by Barbagli et al. in 2008 in European Urology, this technique avoids dissection of the BS muscle from the corpus spongiosum entirely.[4]

Surgical steps​

  1. Perineal incision — standard midline perineal incision.
  2. Muscle preservation — instead of splitting the BS muscle in the midline, access the bulbar urethra by dissecting between the BS muscle and the ischiocavernosus muscle on one side, leaving the BS muscle attached to the corpus spongiosum and the central tendon of the perineum intact.
  3. One-sided mobilization — the urethra is mobilized from the corpora cavernosa on one side only, preserving the contralateral neurovascular attachments.
  4. Urethrotomy and graft placement — a dorsal or ventral urethrotomy is performed, and an oral mucosal graft is placed as an onlay.
  5. Closure — the graft is sutured in place and the wound is closed without disrupting the BS muscle.[4]

Original series (Barbagli 2008)​

  • 12 patients, mean age 43.6 yr, mean stricture length 4.47 cm
  • 6 ventral onlay + 6 dorsal onlay BMG
  • 0% postvoid dribbling and 0% semen sequestration at 6 and 12 months
  • 0% stricture recurrence at mean 15.25 mo
  • No urethral sacculation on voiding cystourethrography[4]

Technique 2 — Kulkarni One-Sided Dorsolateral Onlay Urethroplasty​

Described by Kulkarni et al., this technique is specifically designed for long-segment and panurethral strictures (>8 cm). It inherently spares the contralateral BS muscle and neurovascular bundle through one-sided dissection.[6][7][8]

Surgical steps​

  1. Perineal approach with penile invagination — the entire anterior urethra is accessed through a single perineal incision by invaginating the penile skin.
  2. One-sided urethral mobilization — the urethra is mobilized from the corpora cavernosa on one side only (typically the left), preserving the contralateral lateral vascular supply, BS muscle attachment, and perineal nerve branches.
  3. Dorsolateral urethrotomy — the strictured urethra is opened along the dorsolateral surface.
  4. Graft placement — a buccal mucosal graft (or penile skin graft) is placed as a dorsolateral onlay, sutured to the tunica albuginea of the corpora cavernosa on one side and the urethral margin on the other.
  5. Closure — the urethra is rotated back to its anatomic position.[6][7][8]

Outcomes of the Kulkarni technique​

StudynMean Stricture LengthSuccessFollow-upKey Findings
Spencer 2018 (multi-institutional)[8]7313.6 cm88%44 moIPSS improved 23 → 10 (p < 0.001); PVD 45%; chordee 25%
Kartal 2020 (vs Barbagli)[7]31 vs 37>8 cm87.1% vs 70.3%~60 moShorter OR time, less blood loss, fewer complications with Kulkarni
Zumrutbas 2020[15]3513.6 cm82.9%≥6 mo88.6% satisfaction; recurrence 35.7% in age >65 vs 4.8% in ≤65
Takekawa 2025[6]3944 mm (median)89.7%12 mo (median)SHIM unchanged; OMG 80% vs PSG 95.8% success
Palminteri 2016 (penile skin)[14]375 cm (median)92%21 moSafe with penile skin graft; 81% had prior treatments

Kulkarni vs. conventional Barbagli dorsal onlay​

The comparative study by Kartal et al. (2020) of strictures >8 cm demonstrated significant advantages for the Kulkarni technique:[7]

  • Shorter operative time — 179.5 vs 195.5 min (p = 0.037)
  • Less blood loss — 164.3 vs 202.4 mL (p = 0.033)
  • Shorter hospital stay — 3.5 vs 4.4 days (p = 0.002)
  • Fewer perioperative complications — 16.1% vs 37.8% (p = 0.046)
  • Higher success rate — 87.1% vs 70.3% (not statistically significant in this sample)

The Controversy — Does BS Muscle Sparing Actually Matter?​

This is the central debate. The evidence is conflicting.

StudyDesignnTechniquePVD (sparing vs non-sparing)EjD (sparing vs non-sparing)Conclusion
Barbagli 2008[4]Case series12Dorsal / ventral onlay0% (all sparing)0% (all sparing)Feasible, no PVD/EjD
Fredrick / Vanni 2017[3]Matched case-control50Mixed EPA / augmentationNo difference (p = 0.90)No difference (p = 0.90)No benefit
Elkady 2019[2]Prospective RCT50Ventral onlay BMG4% vs 36% (significant)8% vs 40% (significant)Significant benefit
Farias / Martins 2025[1]Prospective interventional70EPA2.9% vs 5.7% (p = 0.64)No difference (p = 0.72)No benefit
Theisen 2021[5]Prospective cohort728All anterior——EjD/PVD occur equally after penile repairs (no BS muscle involved)

Studies supporting muscle sparing​

  • Elkady 2019 — Prospective RCT, 50 patients (ventral onlay BMG): PVD in 1/25 (4%) muscle-sparing vs 9/25 (36%) non-sparing; semen sequestration in 2/25 (8%) vs 10/25 (40%). Both differences statistically significant.[2]
  • Barbagli 2008 — 0% PVD and 0% semen sequestration in all 12 muscle-sparing patients.[4]

Studies showing no benefit​

  • Fredrick / Vanni 2017 — Multi-institutional matched case-control, 50 patients (25 vs 25): MSHQ scores were identical between groups (15.24 vs 15.40, p = 0.90). No difference in PVD or ejaculatory function perception.[3]
  • Farias / Martins 2025 — Prospective interventional, 70 patients (35 vs 35, EPA): MSHQ-EjD-SF decrease was 0.59 vs 0.67 (p = 0.72). PVD: 1 vs 2 patients (p = 0.64). The authors concluded that midline division of the BS muscle does not lead to significant damage to muscle innervation and vascularization.[1]

Evidence challenging the BS-muscle-damage theory entirely​

  • Theisen 2021 — 728 patients: EjD and PVD occurred at similar rates after penile and bulbar urethroplasty. Since the BS muscle is not involved in penile repairs, this argues against BS muscle damage as the primary etiology of these symptoms. The authors found a significant association between EjD and PVD (p < 0.05).[5]

Postvoid Dribbling and Ejaculatory Dysfunction — The Bigger Picture​

Regardless of muscle-sparing technique, PVD and EjD are extremely common after all forms of anterior urethroplasty:[5][16]

  • PVD — 28–70% depending on series and technique (higher with augmentation than anastomotic: 70% vs 52%, p = 0.0001)[5][16]
  • EjD — 67% overall in a 728-patient series[5]
  • PVD reported more often after dorsal onlay (28.1%) than anastomotic (8.3%, p < 0.001)[16]
  • Tethering with erections more common after anastomotic (23.4%) than dorsal onlay (3.1%, p = 0.008)[16]

The finding that EjD and PVD occur at similar rates after penile repairs (where the BS muscle is not involved) strongly suggests the etiology is multifactorial and not solely attributable to BS muscle disruption. Potential contributing factors include urethral compliance changes, scar tissue, altered urethral caliber, and neurological disruption beyond the BS muscle itself.[5]

For the broader non-transecting evidence base on sexual dysfunction after bulbar urethroplasty, see Chapman 2019 (multi-institutional NT vs T comparative analysis), Oszczudlowski 2023 meta-analysis, Virasoro / DeLong 2020 review, the Andrich / Mundy 2012 preliminary NT report, and Verla 2019 vessel-sparing operative video.[9][10][11][12][13]

Practical Considerations​

When to consider muscle sparing​

  • The Kulkarni one-sided dissection is particularly valuable for long-segment and panurethral strictures (>8 cm), where it provides reduced blood loss, shorter operative time, and access to the entire anterior urethra through a single perineal incision.[6][7]
  • For standard bulbar urethroplasty, the evidence does not strongly support routine muscle sparing as a standalone modification, given the conflicting data.[1][3]

Technical limitations​

  • Muscle-sparing approaches may provide limited exposure, particularly for complex or recurrent strictures.
  • The Kulkarni technique requires penile invagination, which adds technical complexity.
  • One-sided dissection may limit options for future revision surgery on the same side.

Key Takeaways​

  • Barbagli's muscle- and nerve-sparing technique (2008) avoids midline BS muscle splitting by accessing the urethra between the BS and ischiocavernosus muscles, preserving the central tendon.
  • Kulkarni's one-sided dorsolateral technique inherently spares the contralateral BS muscle and is the preferred approach for long-segment / panurethral strictures, with 87–90% success and preserved erectile function.
  • The evidence on whether BS muscle sparing improves PVD and EjD is conflicting: one RCT (Elkady) shows significant benefit, while two comparative studies (Fredrick / Vanni, Farias / Martins) show no difference.
  • A 728-patient cohort (Theisen) challenges the BS-muscle-damage theory entirely, as EjD and PVD occur at similar rates after penile repairs where the BS muscle is not involved.
  • PVD and EjD remain common after all forms of anterior urethroplasty (28–70%), suggesting a multifactorial etiology beyond BS muscle disruption alone.

Videos​

Bulbospongiosus Muscle-Sparing Buccal Mucosa Urethroplasty
TURNS (Trauma and Urologic Reconstruction Network of Surgeons)

References​

  1. Farias RB, Martins FE. Comparison of postoperative outcomes related to ejaculatory function and post-micturition dribbling between bulbospongiosus muscle sparing and non-sparing anastomotic urethroplasty techniques. Sci Rep. 2025;15(1):37558. doi:10.1038/s41598-025-23625-4.
  2. Elkady E, Dawod T, Teleb M, Shabana W. Bulbospongiosus muscle sparing urethroplasty versus standard urethroplasty: a comparative study. Urology. 2019;126:217-221. doi:10.1016/j.urology.2018.12.028.
  3. Fredrick A, Erickson BA, Stensland K, Vanni AJ. Functional effects of bulbospongiosus muscle sparing on ejaculatory function and post-void dribbling after bulbar urethroplasty. J Urol. 2017;197(3 Pt 1):738-743. doi:10.1016/j.juro.2016.09.083.
  4. Barbagli G, De Stefani S, Annino F, De Carne C, Bianchi G. Muscle- and nerve-sparing bulbar urethroplasty: a new technique. Eur Urol. 2008;54(2):335-43. doi:10.1016/j.eururo.2008.03.018.
  5. Theisen KM, Soubra A, Grove S, et al. Association between ejaculatory dysfunction and post-void dribbling after urethroplasty. Urology. 2021;153:320-326. doi:10.1016/j.urology.2021.04.016.
  6. Takekawa K, Horiguchi A, Shinchi M, et al. One-sided dorsal onlay urethroplasty with penile invagination (Kulkarni urethroplasty) for complex anterior urethral strictures: a single-center experience. Int J Urol. 2025;32(6):749-755. doi:10.1111/iju.70048.
  7. Kartal I, Çimen S, Kokurcan A, et al. Comparison between dorsal onlay and one-sided dorsolateral onlay buccal mucosal graft urethroplasty in long anterior urethral strictures. Int J Urol. 2020;27(9):719-724. doi:10.1111/iju.14286.
  8. Spencer J, Blakely S, Daugherty M, et al. Clinical and patient-reported outcomes of 1-sided anterior urethroplasty for long-segment or panurethral strictures. Urology. 2018;111:208-213. doi:10.1016/j.urology.2017.08.029.
  9. Chapman DW, Cotter K, Johnsen NV, et al. Nontransecting techniques reduce sexual dysfunction after anastomotic bulbar urethroplasty: results of a multi-institutional comparative analysis. J Urol. 2019;201(2):364-370. doi:10.1016/j.juro.2018.09.051.
  10. Oszczudlowski M, Yepes C, Dobruch J, Martins FE. Outcomes of transecting versus non-transecting urethroplasty for bulbar urethral stricture: a meta-analysis. BJU Int. 2023;132(3):252-261. doi:10.1111/bju.16108.
  11. Virasoro R, DeLong JM. Non-transecting bulbar urethroplasty is favored over transecting techniques. World J Urol. 2020;38(12):3013-3018. doi:10.1007/s00345-019-02867-8.
  12. Andrich DE, Mundy AR. Non-transecting anastomotic bulbar urethroplasty: a preliminary report. BJU Int. 2012;109(7):1090-4. doi:10.1111/j.1464-410X.2011.10508.x.
  13. Verla W, Oosterlinck W, Waterloos M, Lumen N. Vessel-sparing excision and primary anastomosis. J Vis Exp. 2019;(143). doi:10.3791/58214.
  14. Palminteri E, Berdondini E, Lumen N, et al. Kulkarni dorsolateral graft urethroplasty using penile skin. Urology. 2016;90:179-83. doi:10.1016/j.urology.2015.12.014.
  15. Zumrutbas AE, Ozlulerden Y, Celen S, Kucuker K, Aybek Z. The outcomes of Kulkarni's one-stage oral mucosa graft urethroplasty in patients with panurethral stricture: a single centre experience. World J Urol. 2020;38(1):175-181. doi:10.1007/s00345-019-02758-y.
  16. Furr JR, Wisenbaugh ES, Gelman J. Urinary and sexual outcomes following bulbar urethroplasty — an analysis of 2 common approaches. Urology. 2019;130:162-166. doi:10.1016/j.urology.2019.02.042.