UROLOGICAL SURVEY   ( Download pdf )

 

RECONSTRUCTIVE UROLOGY

Randomized comparative study between buccal mucosal and acellular bladder matrix grafts in complex anterior urethral strictures
El Kassaby AW, AbouShwareb T, Atala A
Departments of Urology and Institute for Regenerative Medicine, Wake Forest University Health Sciences, Winston-Salem, North Carolina, and Ain Shams University, Cairo, Egypt
J Urol. 2008; 179: 1432-6

  • Purpose: Urethral strictures have been a reconstructive dilemma for many years due to the limited availability of tissue substitutes and incidence of recurrence. Buccal mucosal grafts have been a favored material in instances where penile skin is unavailable due to its durability and excellent graft survival. Recently collagen based matrices derived from the bladder have been used successfully in patients with stricture disease and hypospadias. We performed a randomized comparative study to assess the outcome of the acellular bladder matrix compared to buccal mucosa in patients with complex urethral strictures.
  • Materials and Methods: Human demineralized bone matrix, obtained from cadaveric donors, was processed and prepared for use as an off-the-shelf material. Thirty patients with stricture 21 to 59 years old (mean 36.2) were enrolled and assessed using a standard protocol. The stricture length ranged from 2 to 18 cm (mean 6.9), of which 11 patients had bulbar, 7 had pendulous and 12 had combined bulbo-pendulous strictures. Of the 30 patients, 7 had received no previous intervention while the remaining 23 had undergone 1 to 7 procedures (mean 1.9). All patients were randomized and alternatively assigned to receive either buccal mucosa or demineralized bone matrix and underwent an onlay procedure.
  • Results: All patients except 2 who were lost during followup were followed for 18 to 36 months (mean 25). In patients with a healthy urethral bed (less than 2 prior operations), the success rate of buccal mucosa grafts (10 of 10) was similar to the bladder matrix grafts (8 of 9) in terms of patency. In patients with an unhealthy urethral bed (more than 2 prior operations), only 2 of 6 patients with a bladder matrix graft were successful, whereas all 5 patients with a buccal mucosa graft had a patent urethra. Postoperative uroflowmetry showed significant voiding improvement in both groups. Histology of the graft biopsies showed normal urethral tissue characteristics.
  • Conclusions: This study demonstrates that the use of acellular bladder matrix is a viable option for urethral repair. Demineralized bone matrix as an off-the-shelf biomaterial achieves the best results in patients with a healthy urethral bed, no spongio-fibrosis and good urethral mucosa.

  • Editorial Comment
    In recent publications, we have seen the reporting of various off-shelf materials for urethral reconstruction (1,2). Different to the previous publications, the authors compared their shelf material “acellular bladder matrix” against the golden standard of the buccal mucosa graft.
    As we all know in the almost virgin wound bed, the first approach always seems to work--if performed correctly. Therefore we should all keep in mind that the first approach might be the most important in order to have a good outcome in the long term (3). In those cases where more than two previous surgeries were performed, the best material still seems to be the buccal mucosa. From this well-designed study, we can learn that as long as we do not have the perfect matrix, we can use one off-shelf in the first run thereby avoiding the additional surgeries needed to harvest buccal mucosa with a similar outcome within a follow-up of mean two years. With the patient we have to make the decision if they are already ready to use this material in the first or second approach (4).

References
1. El-Kassaby AW, Retik AB, Yoo JJ, Atala A: Urethral stricture repair with an off-the-shelf collagen matrix. J Urol. 2003; 169: 170-3; discussion 173.
2. Fiala R, Vidlar A, Vrtal R, Belej K, Student V: Porcine small intestinal submucosa graft for repair of anterior urethral strictures. Eur Urol. 2007; 51: 1702-8; discussion 1708.
3. Sievert KD, Feil G, Renninger M, Selent C, Maurer S, Conrad S, at al.: [Tissue engineering and stem cell research in urology for a reconstructive or regenerative treatment approach] Urologe A. 2007; 46: 1224-30. German.
4. Stenzl A. Urethral reconstruction: new materials but old problems? Eur Urol. 2003; 44: 610.

Dr. Karl-Dietrich Sievert &
Dr. Arnulf Stenzl
Department of Urology
Eberhard-Karls-University Tuebingen
Tuebingen, Germany
E-mail: arnulf.stenzl@med.uni-tuebingen.de