nitinol and Urethral-Stricture

The purpose of this study was to evaluate the long-term clinical efficacy of temporary placement of covered retrievable stents in the management of recurrent urethral strictures.. During the period December 1998-December 2005, 32 men and one adolescent boy (mean age, 48.6 years; range, 16-73 years) with recurrent urethral strictures underwent fluoroscopically guided insertion of a total of 68 stents. Patients without complications underwent elective stent removal 2 or 4 months after stent insertion. Rates of clinical success (long-term clinical and radiographic resolution of urethral strictures) were assessed. The Mann-Whitney U test was used to compare the duration of stent placement in patients with long-term clinical resolution with that in patients with stricture relapse.. Clinical success was achieved in 18 (55%) of the 33 patients. The mean duration of stent placement in patients with clinical success was significantly different from that in patients who had recurrences (p < 0.0001). Stricture relapse did not occur in only four (20%) of 20 cases of stent placement for 2 months. All 14 stent placements lasting at least 4 months resulted in long-term resolution after a mean follow-up period of 3.6 years. The most common complications necessitating early stent removal were stent migration (33.8% of stents) and tissue hyperplasia (20.6% of stents).. Placement of a covered retrievable stent for a minimum of 4 months is effective in inducing long-term resolution of refractory urethral strictures. Stent migration remains the largest obstacle in achieving adequate duration of stent placement.

Topics: Adolescent; Adult; Aged; Alloys; Device Removal; Humans; Longitudinal Studies; Male; Middle Aged; Prosthesis Implantation; Radiography; Secondary Prevention; Stents; Treatment Outcome; Urethral Stricture

To evaluate the efficacy of the Memokath stent in managing recurrent bulbar urethral strictures.. This is an investigative pilot stage 2A study in patients with a recurrent bulbar urethral stricture who underwent a Memokath stent implant from January 2014 to January 2016 in a single high-volume center for urethral reconstruction. The Memokath stent (Pnn Medical A/S, Kvistgaard, Denmark) was manufactured from nitinol, a biocompatible alloy of nickel and titanium, which was endoscopically placed. It had a 24-Fr outside diameter and was preloaded on a disposable delivery device. When correctly positioned, the stent was anchored by a warm water (55°C) instillation, which expanded the proximal end of the stent from 24 to 42 Fr .The stent was provided in lengths of 3-7 cm in 1-cm increments.. Sixteen patients were included in the study. The median follow-up was 16 months. In 7 patients (43.7%), the stent was removed within 1 year. The main adverse events were pain, encrustations, stones, and recurrent strictures. Four patients (25%) were considered a success and 12 (75%) were failures. Study limitations include the small sample.. The Memokath stent was deemed to be not clinically helpful and had significant side effects, and therefore should not be considered a treatment option for men with bulbar urethral strictures.

Topics: Adult; Aged; Aged, 80 and over; Alloys; Cystoscopy; Device Removal; Follow-Up Studies; Humans; Male; Middle Aged; Pilot Projects; Plastic Surgery Procedures; Prosthesis Failure; Recurrence; Reoperation; Retrospective Studies; Stents; Time Factors; Ultrasonography; Urethra; Urethral Stricture; Urography; Urologic Surgical Procedures, Male

The incidence of urethral strictures and their recurrences is high. The effectiveness of optical urethrotomy in men is insufficient. Reconstructive urethroplasty is the "gold standard", but it is traumatic and accompanied by a prolonged period of rehabilitation. The results of using metal endourethral stents were unsatisfactory because of their incrustation and migration. This paper presents the results treating urethral strictures of various etiologies in 22 patients, who underwent optical urethrotomy with temporary placement of a new generation polyurethane-covered nitinol stents. After removing the stents from 3 to 8 months after implantation, there was a stable effect of preserving the urethral lumen. The recurrence of the stricture occurred in 1 case 1 month following the stent removal. In other cases, there were no recurrences over 1-3 year follow-up. We consider placing an internal stent as an alternative adjunctive treatment of patients with urethral strictures.

Topics: Alloys; Coated Materials, Biocompatible; Female; Follow-Up Studies; Humans; Male; Polyurethanes; Stents; Ureteroscopy; Urethral Stricture

The purpose of this article is to compare the clinical effectiveness and complications of externally and internally covered stents for the treatment of benign urethral strictures.. From July 2002 to June 2010, 59 retrievable self-expandable polytetrafluoroethylene-covered nitinol stents were placed in 33 men with benign urethral strictures. These included 34 internally covered stents placed in 18 patients (group I) and 25 externally covered stents in 15 patients (group E). Stents were routinely removed 4 months after placement from patients who experienced no complications. Complications, duration of stent placement, removal techniques, and maintained patency rates were compared in the two groups.. Twenty-eight complications (82.4%) occurred in 15 patients in group I, whereas 12 complications (48%) occurred in six patients in group E (p=0.005). Three (16.7%) patients in group I and nine (60%) in group E had their stents electively removed without complications (p=0.010). Stent migration was more frequent in group I (47.1%) than in group E (24.0%). No tissue ingrowth was detected in group E, whereas six cases of tissue ingrowth occurred in group I (p=0.034). The standard technique was used more frequently in group E (70.8%). The median stent indwelling period was significantly shorter in group I than in group E (51.5 vs 114 days; p=0.34).. Despite their relatively high complication rates, externally covered stents are more effective with fewer complications than internally covered stents in the treatment of benign urethral strictures.

Topics: Adult; Aged; Alloys; Chi-Square Distribution; Coated Materials, Biocompatible; Device Removal; Humans; Male; Middle Aged; Polytetrafluoroethylene; Prosthesis Design; Radiography, Interventional; Retrospective Studies; Statistics, Nonparametric; Stents; Treatment Outcome; Urethral Stricture

The male urethral stricture treatment is actual clinical issue with its resolution being increasingly frequently based on application of minimum invasive therapeutic interventional uroradiology methods. Since the methodology is applied over the last two decades, the most reasonable therapeutic algorithm has not been defined yet with respect to the correlation with the contemporary surgical treatment. The results of application of the temporary covered self-expandable nitinol Allium stents, which have been applied for the first time ever at our Institution in October 2003. Over the last 3 years, the method was applied in 40 males, averagely aged 54 years with urethral strictures previously treated by urological methods. In four cases, stent placement was performed after endourethral incision. The most common etiology of the stricture was the posttraumatic (55%), post-inflammatory (32%) and iatrogenic (10%). In all the cases, stents were removed 12-14 months after their insertions. The results are evaluated using uroflowmetry and urethrocystography, revealing in 85% of the cases permanent recanalization free of dysuric complaints. Development of a stricture on the anterior stent end was evidenced in 15% of the cases.

Topics: Adult; Aged; Alloys; Biocompatible Materials; Equipment Design; Humans; Male; Middle Aged; Stents; Urethral Stricture

To investigate the clinical effectiveness of a covered, retrievable, expandable nitinol stent in treating traumatic urethral strictures near the external sphincter.. The stent was 10 mm in diameter when fully expanded and 40-50 mm long. To make it removable, two nylon drawstrings were attached to its lower inner margin. Twelve consecutive men (19-67 years; mean age, 47 years) with traumatic urethral strictures near the external sphincter that were refractory to endoscopic urethrotomy were treated. With fluoroscopic guidance, a stent was placed to completely bridge the external sphincter. The stent was electively removed with a retrieval hook wire 2 months after placement. Stent placement and removal were successful in all patients, with no procedural complications.. Mean maximum urine flow rate was 5 mL/sec (range, 3-7 mL/sec) before stent placement and 27 mL/sec (range, 16-40 mL/sec) at 1 week after placement. During the mean follow-up of 20 months (range, 2-37 months) after the first stent removal, strictures recurred in eight of 12 patients. For the eight patients with recurrence, a second stent was placed and 4 months later was removed from seven of the eight patients. During the mean follow-up of 18 months (range, 4-32 months) after the second stent removal, strictures recurred in two patients, in whom a third stent was placed and then removed 4 months later, with good results. Four (33%) of 12 patients, five (62%) of eight patients, and two (100%) of two patients were successfully treated with placement of the first stent, the second stent, and the third stent, respectively. In the remaining patient, the second stent remains in place.. Placement of a covered, retrievable, expandable nitinol stent seems to be effective in treating urethral strictures near the external sphincter and warrants further investigation.

Topics: Adult; Aged; Alloys; Device Removal; Follow-Up Studies; Humans; Male; Middle Aged; Radiography; Recurrence; Stents; Treatment Outcome; Urethra; Urethral Stricture

No information has been available to date on the long-term behavior of nitinol (nickel-titanium alloy) urethral stents. In the present study, prostheses of this type were implanted in 18 German shepherd dogs in order to evaluate the reaction of the mucosa, muscles and periurethral tissue. Follow-up examinations performed after 1 week, and 1, 3, 6, 12 and 18 months included urine, macroscopic, radiologic, histologic and scanning electron microscopic analyses. Despite the excellent biocompatibility of the material, with no evidence of foreign body reactions or corrosion, there were no complete incorporations of the stent by epithelialization. Clinical application therefore appears to be problematic.

Topics: Alloys; Animals; Dogs; Stents; Urethra; Urethral Stricture

Three types of urethral stents can be used in the treatment of recurrent strictures: Urolume/Wallstent is a self-expanding mesh which is incorporated into the urethral epithelium; the ASI Titanium stent is a short rigid mesh of Titanium wire which is also incorporated into the urethra; Nitinol is a flexible spring in one or two parts connected by a steel wire. It remains endoluminal. The Urolume/Wallstent has been used since 1987. It is indicated in iatrogenic strictures. No statistical results are presented. The ASI stent should be reserved for strictures of the prostatic and posterior urethra. The Niticol UroCoil system can be used at all levels of the urethra; two models are available: simple or twin. The author has inserted 65 stents in 56 patients. The stent was removed after one year in 41 patients. The use of these stents has considerably decreased the number of repeated dilatations and urethrotomies.

Topics: Alloys; Catheterization; Contraindications; Equipment Design; Humans; Male; Recurrence; Stents; Surface Properties; Surgical Mesh; Time Factors; Titanium; Urethra; Urethral Stricture