Relapses of urethral strictures associated with a pelvic ring fracture and osteosynthesis: the features of treatment and prevention

Introduction

The rate of pelvic bone fractures varies from 4 to 17% among all bone fractures in men, and in the structure of combined injuries, such fractures are observed in 17–39% of cases [1]. The main mechanism of damage of pelvic bones is high energetic impact factors that occur as a result of falls, car accidents, and body compression [2][3].

Urethral injuries associated with pelvic bone fractures are characterized by the instability of the injured area [3][4][5]. Thus, the risk of partial or complete urethral rupture with further formation of posttraumatic stricture is the highest in patients with fractures that involve the anterior pelvic ring, in particular, fractures of the medial section and inferior pubic ramus with the displacement of fragments and rapture of the pubic symphysis. This occurs because of the connection of pubic bones with pubic symphysis with the urogenital diaphragm, puboprostatic and perineal ligaments. Andrich et al. [6] suggested mechanisms of urethral damage considering the transmission of the force vectors via the pubic ligaments and urogenital diaphragm and Tile fracture classification [7]. Severe pelvic fractures that lead to urethral injuries can be rotationally horizontally unstable like in the cases with fractures with lateral compression or “open book” fracture type. Besides, they can be vertically and rotationally unstable like in the cases of typical Malgaigne’s pelvic fracture. As a rule, rotationally unstable fractures result from car accidents. Vertically and rotationally unstable fractures usually occur after a fall from a height.

In general, pelvic bone fractures with fragment displacement are associated with distraction damage of the urethra in around 10% of cases [4][8]. It requires both traumatological and urological care [9].

The authors apply the methods of external and internal fixation to stabilize the anterior sections of the pelvic ring. The installation of metal structures for external fixation is preferable in the case of emergent medical care [10]. Internal fixation is characterized by a significantly better stabilization of fractures in comparison with eternal fixation. Various methods of anterior stabilizations of pelvic fractures with internal fixation are described [7]. The standard method of stabilization in patients with these fractures is open reduction internal fixation with a two-hole or four-hole dynamic compression plate (DCP 4.5 mm). The DCP can be placed either on the upper edge of the symphysis or the anterior surface (Fig. 1). The mounting of the plate on the upper edge is technically more complicated and should be followed by the manual and endoscopic control of the position of screws, as well as intraoperative X-ray control. In patients with pubic ramus fractures, the plate is primarily located on the anterior pubic surface [10]. The application of screws in osteosynthesis includes their fixation throughout all the bone (Fig. 2). The optimal position of the screw tips is 0.2–0.3 mm protrusion on the posterior surface [11].

A decision is made on the removal of steel constructions individually in each case. In general, the removal of the metal construction that fixes pelvic bones is not recommended because of complicated surgical accesses and the risk of damage to peripheral nerves. The main indications for the removal of metal construction in patients with such fractures include irritation of soft tissues or pain syndrome associated with the implant, hypersensitivity reaction of allergic-type, and infection [11]. Thus, in the majority of cases, the grafts are not removed.

The study aimed to evaluate the influence of extramedullary osteosynthesis in patients with pelvic ring fracture on the treatment outcome of posttraumatic urethral strictures.

Materials and Methods

The authors selected 420 patients with post-traumatic urethral strictures among 754 patients that underwent surgical treatment for urethral structures in 2010–2019. Pelvic bone fractures were observed in 173 of them. The study included 17 patients with distractional urethral rupture and fractures of the anterior pelvic ring (Type B and C) stabilized by the method of extramedullary osteosynthesis. In all patients, X-ray imaging showed that the screw protrusion through the posterior surface of the pelvic symphysis (in the lesser pelvis) was 1.0–2.0 cm.

The mean age of patients was 35.8 ±10.2 (19–61) years old. Strictures were primarily localized in the membranous part in 10 cases (58.8%), and in 7 patients (41.2%) – in the bulbo-membranous part. The mean length of strictures was 1.47 ± 0.5 (0.5–2.5) cm. The mean time after the injury was 6.6 ± 1.3 (4–10) months. All patients had cystostomy drainage installed in the acute posttraumatic period in their local hospitals.

Statistical analysis. The authors used the methods of descriptive statistics: the rate of qualitative parameters, the mean and standard errors of the mean, minimal and maximal values for quantitative parameters. Statistical processing of the results was performed with the software SPSS Statistics v. 17.0.

Results

All patients had anastomotic urethroplasty via transperineal access. There were no complications observed that required additional surgical interventions in the early postoperative period. Unassisted urination was restored in all patients by Days 14–15 after the surgery.

Fifteen patients (29.4%) developed acute urinary retention, which required cystostomy, during the first month after the surgery. Four patients (23.5%) examined 3 months after had an obstructive type of urination (Q_max < 10 ml/s) with the residual urine volume more than 150 ml. Retrograde urethrography revealed early relapse of urethral stricture (within 3 months of the observation) in all 9 cases (52.9%), which could be associated with excessive protrusion of osteosynthesis screws in the pelviс cavity that was visible during some surgical interventions in the operative wound during urethral resection.

Before planning the repeated urethroplasty, osteosynthesis constructions that stabilized the pelvis were removed in all patients at the Department of Orthopedics. The repeated urethroplasty was performed a month after the removal of osteosynthesis. By the time of the repeated surgery, the length of strictures increased on average by 0.78 ± 0.3 (0.5–1.5) cm. However, it did not prevent the repeated urethral resection with end-to-end anastomosis.

After repeated urethroplasty and 27 months (12–44) median, there were no cases of urethral stricture relapse observed. At the same time, in the other 8 patients, there were no cases of urethral stricture relapse and progression revealed within the median time of observation 33 months (12‒128).

Clinical case. Patient C. aged 30 years old got into a car accident and received a combined injury: the rapture of the right sacroiliac joint, splintered fracture of the right ventral arc, inferior left pubic ramus fracture with sharp fragment displacement and rapture of the pelvic symphysis, distraction urethral rupture, and bladder rupture. Urgent open reduction with internal fixation was performed with a dynamic compression plate (DCP 0.5 mm) followed by suturing of the bladder and cystostomy.

Eight months after the surgery, the patient was diagnosed with the obliteration of the membranous urethra and proximal bulbose urethra 2.0 cm long (Fig. 3). The patient underwent anastomotic urethroplasty. The post-operative period was without complications. Unassisted urination was restored on Day 14 after the surgery. The patient had acute urine retention and cystostomy five weeks after the surgery. Recurrent stricture of the bulbo-membrane urethral was revealed during the repeated application to the hospital (Fig. 4). Osteosynthesis was removed (Fig. 5). A month later, repeated resection of the bulbo-membranous urethra with end-to-end anastomosis was removed.

The postoperative period was without complications. On Day 12, pericatheter ascending urethrography showed that a contrasting agent easily passed through the urethra to the bladder. There were no signs of extravasation of the contrasting agent (Fig. 6). The urethral catheter was removed; adequate unassisted urination was restored. A month after the surgery, uroflowmetry showed that the maximum urine flow rate was 25 ml/s. There were no signs of residual urine revealed.

Discussion

Fractures (Fig. 7) that involve pelvic ramus and that are characterized by vertical and rotational pelvic instability (Type C), have the highest risk of urethral damage unlike stable pelvic fractures (Type A) that are rarely associated with urethral damage. A decision on the surgical treatment for pelvic fractures is made based on the fracture type. Type A requires surgical treatment in exceptional cases, Type B involves the stabilization of the anterior sections of the pelvis, and Type C needs the stabilization of the whole pelvis [10].

Traumatologists presently prefer the tactics of surgical stabilization of pubic bone structures with extramedullary osteosynthesis with a plate and screws fixed through the bones. It must be highlighted that the protrusion of screw tips on the posterior surface of the bone should not be more than 0.2‒0.3 cm. In their practice, the authors faced 17 clinical cases with screw tips protrusion up to 1.0‒2.0 cm. As a rule, traumatologists tend not to remove osteosynthesis material from the pubic bones. Based on the generally accepted practice, the authors performed anastomotic urethroplasty of the membranous and bulbo-membranous strictures that resulted from severe fractures of the anterior pelvic bones in 17 patients. However, in 52.9% of cases, early recurrent urethral strictures (obliterations) were observed in the same localization by more extended. This required the removal of osteosynthesis and repeated anastomotic urethroplasty. Perfect clinical outcomes were achieved in all 17 cases within the median of observation 28 months (12‒128) months. Thus, a high rate of stricture disease recurrence (52.9%) among patients with pubic osteosynthesis with screw protrusion that is longer than acceptable indicates the necessity to reconsider the tactics of treatment in favor of the removal of osteosynthesis material before the planned urethroplasty. It will prevent urethral stricture recurrence.

As a rule, the primary delayed treatment for urethral strictures includes the excision of scar tissue of the urethra and the formation of a direct anastomosis between the healthy parts of the urethra [4][8][12][13][14][15][16]. This approach allows the specialists to remove a diastasis 2‒4 cm long due to mobilization of the bulbose urethra and its elasticity [17, 18, 19, 20, 21, 22]. When the proximal urethral end cannot be reached or the anastomosis is tensed, it is recommended to consider additional methods like beveled anastomosis, incision of the intercrural space, separation of the cavernous bodies, rerouting of the urethra under the cavernous body pedicle, partial or complete symphysis excision [4][8][23]. A multicenter study performed by Johnsen et al. showed that in 78 out of 122 patients (64%) with posttraumatic urethral strictures, urethral patency was restored after the formation of a direct anastomosis with the dissection of the scar tissue and mobilization of the urethra. One or several additional reconstructive maneuvers were used during urethroplasty in 44 patients (36%). Partial lower pubectomy was performed in 13 of them (11%). Complete pubectomy was made in 3 (2%) patients. Supracrural rerouting of the urethra was needed in 2 patients (2%). The length of the urethral stricture in patients that did not require additional interventions significantly differed from those patients that needed one or more interventions (p = 0.008 and p = 0.01, respectively). The authors state that urethroplasty in patients with strictures associated with pelvic bone fractures remains a difficult clinical task. Even though such surgery is primarily successful, the surgeons have to be ready for additional surgical interventions and maneuvers [24]. However, considering long-term experience in the treatment of such patients, the authors concluded that such additional techniques as lower pubectomy or complete pubectomy and supracrural rerouting of the urethra do not improve the treatment outcomes and do not prevent the recurrence of urethral strictures. At the same time, it significantly increases the rate of such complications as erectile dysfunction and urine incontinence, and in some cases, they may lead to the development of osteomyelitis. In other words, additional surgical techniques, apart from standard anastomotic urethroplasty, were not applied in any of 17 presented cases of patients with severe anterior pelvic fractures.

Conclusion

A high recurrence rate of urethral strictures after primary surgery for traumatic strictures of the membranous urethra caused by stabilized fractures of pelvic bones is associated with an improper location of the osteosynthesis screws that are inserted too deep in the pelvis. The treatment tactics for such patients should be chosen together with traumatologists, and surgical treatment for urethral strictures associated with a pelvic ring fracture and osteosynthesis is advisable after removal of the metal structures fixing the pelvic bones. Since the excessive retropubic protrusion of screws is associated with a large area of periurethral fibrous inflammation, it provides the risks of stricture disease relapse in the case of urethral surgery preceding the removal of metal structures.