IschioPubic Osteotomy, A Simple and Effective Technique for Pelvic Ring Closure in Repair of Classic Exstrophy Bladder.

AIM: The aim of this study is to report the technique and outcome of ischiopubic (IP) osteotomy for pelvic ring closure in classic exstrophy bladder.
METHODS: A total of 85 male classic exstrophies were selected based on trapezoid-shaped space between IP ramus on three-dimensional computed tomography pelvis. Using midline scroto-perineal approach, after bladder plate mobilization and radical corporal detachment; the pelvic surface of superior pubic ramus (SPR) was exposed. Above the obturator canal, H-shaped incision was made on periosteum of the SPR. The horizontal line of H was placed above the obturator canal. Rectangular periosteal flaps above and below the horizontal line was raised. In the subperiosteal plane, curved hemostats encircled the SPR that were divided using a bone drill. On the medial aspect of ischial tuberosity, a notch was created as hinge using a bone drill. Forks of bone holding forceps hooked the pubic bone and tightened for its midline approximation, lengthening of the SPR and inward rotation of IP ramus. Linea alba and pubic bones were approximated with interrupted Polygalactin sutures.
RESULTS: Midline approximation of pubic bone and linea alba was possible in all. There was no injury to obturator nerve, vessels, or other structures .
CONCLUSIONS: IP osteotomy is the safe and effective technique of pelvic ring closure in patients with specific pelvic configuration.

INTRODUCTION

In reconstructive surgery of classic exstrophy bladder (CEB), after bladder closure and epispadias repair, with or without external urethral sphincter reconstruction, anterior abdominal wall defect can be repaired with osteotomy[12] or without osteotomy.[345] In an endeavor to restore normal anatomy for the restoration of normal physiology, various techniques of osteotomy are described, which helps to approximate pubic bones toward midline with an approximation of linea alba to provide an effective protection over the closed bladder. Osteotomy also helps to restore the shape of the urogenital diaphragm from rectangular to triangular, thus facilitating toward the gain of more corporal length after corporoplasty. Osteotomy also helps to shift the wide diastased fork of pubococcygeus muscle toward midline under the bladder base providing the support to the reconstructed bladder neck and bladder base. Morbidity of the additional incision, additional dissection, placement of fixator pins, and limb immobilization has been a limiting factor to wide acceptance of Salters Osteotomy described by Salter and Dubos[67] and Triple Osteotomy described by Gearhart et al.[8] Division of superior pubic ramus (SPR) alone has been reported as not so effective.[910] In novel midline scroto-perineal approach, an ischiopubic (IP) osteotomy is described, but details of technique and precautions regarding safety are not mentioned.[11]

The aim of this communication is to report the technique, safety precautions, case selection, and outcome of a relatively simpler method called IP Osteotomy which can be performed through the same incision used for innervation preservation sphincteroplasty.[11] Pubic bone can be shifted toward the midline, linea alba can be closed in the midline, the urogenital diaphragm is converted into triangular shape without the need of additional skin incision, placement of fixator pins or the need for limb traction, or limb immobilization.

METHODS

From 2004 to 2017, 109 patients of male CEB underwent single-stage total reconstruction using midline scroto-perineal approach with radical corporal detachment and innervation preserving sphincteroplasty. Age at surgery is from 2 months to 20 years. All patients underwent computed tomography scan with three-dimensional reconstruction of the pelvis to study its configuration. Gonads were covered with a gonadal shield.

Selection/exclusion criteria

For IP osteotomy, 85 patients were selected. Those patients were selected where the configuration of the space between IP ramus viewed from below was trapezoid [Figure 1a and b] or rectangular. The patients of incontinent epispadias with narrow pubic diastasis and near triangular urogenital diaphragm were excluded from the study. Patients with a very wide gap between pubic bones indicated by reverse trapezoid shape of the space between IP ramus were also not selected for exclusive IP osteotomy. After the umbilicoplasty incision[12] extraperitoneal bladder plate mobilization, a division of intersymphyseal band and radical corporal detachment with the described technique; medial aspect of ischial tuberosity was exposed on each side with mounted swab dissection strictly in extraperiosteal plane on the medial side of ischial tuberosity [Figure 2a].

Figure 1

(a) Three dimensional view of pelvic configuration viewed from perineum, showing - The gap between Pubic bone (1), Ischio-pubic ramus (2), and Ischial tuberosity (3). Trapezoid shape of Urogenital diaphragm is marked. (b) Three dimensional view of pelvic configuration viewed from above showing - Shortened superior pubic ramus (1), Gap between Pubic bone (2)

Figure 2

(a) Left Ischial tuberosity (1), Notch on left Ischial tuberosity (2), Obturator internus muscle (3), left Ischio pubic ramus (4). (b) Pubic bone (1), Pelvic surface of superior pubic ramus (2), Unnamed vein (3), Obturator nerve and vessel (4), Pubococcygeous muscle (5), Levator ani muscle (6), Right Ischio pubic ramus (7), Glans (8), Left corpora with neurovascular bundle (9), Urethral Plate (10). (c) Pubic bone (1), Upper periosteal flap (2), Unnamed vein (3), Obturator vein and nerve (4), Pubo-coccygeous muscle (5). (d) Pelvic and pectineal surface of pubic bone, exposed after reflecting the flap of periosteum

Pelvic surface of SPR was exposed by retracting the peritoneum covered bowel superiorly, rectus muscle laterally. Deaver's retractors placed over the sponge guarded external iliac vein and artery laterally [Figure 2b]. Mobilised bladder plate was also retracted medially to expose the pelvic surface of SPR, obturator canal taking obturator vein, artery, and nerve [Figure 2b], part of obturator internus and attachment of levator to obturator internus [Figure 2b]. Adequate precaution is taken regarding placement of retractor at this time to ensure that external iliac vessels are surely guarded under the sponge beyond the field, and the pelvic surface of the pubic bone is clearly under vision [Figure 2b and c], with ipsilateral IP ramus from which corpora has already been detached. Over the pelvic surface of SPR, “H”-shaped incision is planned [Figure 2c]. The medial vertical limb of “H” corresponds to the medial edge of obturator foramen but lateral to the body of pubic bone [Figure 2c]. The lateral vertical limb of “H” is clearly away from the course of external iliac vessels protected under retractor [Figure 2c], while the obturator canal lies in the center of two vertical incisions [Figure 2c]. Superior to obturator foramen, two vertical incisions are connected with one horizontal incision, incising the periosteum [Figure 2c]. With periosteum elevator, the flap of periosteum above the horizontal incision over the pectineal surface of the pubic bone is reflected off exposing the bone [Figure 2d]. The rectangular flap of periosteum above the obturator canal is also reflected down protecting the obturator nerve and vessels entering into obturator canal [Figure 2d]. A fine tip curved artery forceps can now be passed subperiosteally above and below to encircle the entire circumference of SPR [Figure 2d]. Positions of retractors, safeguarding of iliac vessels and bowel, was ensured again. With the fine tip electric bone drill, entire superior ramus is divided [Figure 2d]. Flimsy residual bony attachment can be sheared with a gentle hammering of osteotome placed in the groove already made on SPR. Thus subperiosteal superior pubic ramotomy is completed. With same precaution and procedure superior pubic ramotomy is performed on the other side.

To enhance the mobility of pubic bone towards midline by traction with its posterior rotation, provision of a hinge by the creation of a deep notch on the medial aspect of ischial tuberosity is essential. For completion of this task, mobilized corpora are retracted off the medial aspect of ischium [Figure 2a]. With the ball tip electric bone drill, a notch on the medial aspect of ischial tuberosity is created [Figure 2a]. A residual thin film of bone on the lateral wall of ischial tuberosity is fractured by placing the osteotome in the bed of notch with one gentle stroke.

For shifting of pubic bone towards midline and stretching the adductor group of muscles, bone holding forceps is used. Bone holding forceps is opened and its every fork is inserted in obturator foramen of both sides just lateral to the pubic bone through the fibers of adductor group of muscles. The screw of bone holding forceps is gradually tightened to bring both the forks of bone holding forceps closer to each other bringing the pubic bone towards midline. While performing this maneuver, it is mandatory to keep mobilized bladder plate, urethra, and corpora pressed posteriorly in the midline to avoid trapping of the structures anteriorly between narrowed IP ramus. In this position, bone holding forceps is kept for 20 min to effect stretching of adductor group of muscles of the thigh. Three interrupted sutures of number one polygalactin (vicryl) are placed, superior-most suture through the lowermost limit of linea alba attached to the pubic bone, middle one through the periosteum of the outer surface of the pubic bone and third suture either above or below these two sutures. Sutures are tied off, and bone holding forceps is removed. After 8–10 min, the color of glans is inspected as there is a possibility of compression of neurovascular bundle in between the medially shifted IP ramus. If glans congestion is noted, an inferior-most suture is released which automatically corrects the glans congestion. Linea alba is approximated, abdominal skin is closed with umbilicoplasty, penile skin dartos coverage is restored.

Outcome measurements

During the procedure,

Injury to structures such as obturator vein, artery, nerve, and any other structures

Intraoperative complications or difficulties

Ease of pubic bone approximation

Tension-free linea alba approximation

Immediate postoperative

Dehiscence of skin, linea alba, or bladder

Long-term position of approximated pubic bone.

RESULTS

From 2004 to 2017, 85 cases of CEB were operated with this technique. There was no injury to obturator vessels and nerve. There was no osteomyelitis in any case. In preoperative X-ray pelvis, the end on orientation of obturator foramen [Figure 3a] was changed to visible obturator foramen due to a changed axis and midline shifting of the IP bone segment after IP osteotomy and pubic bone approximation in midline [Figure 3b]. Although linea alba could be approximated in 100 percent (%) cases but probably because of intervening cartilage 8–10 mm gap between the medial edge of approximated pubic bone was visible on plain X-ray in all the cases [Figure 3b]. Although a close approximation of pubic bone in midline was confirmed by palpation and inspection during surgery. There was no case of bladder dehiscence, there was one herniation of bowel in the subcutaneous plane through the gap of sutures in linea alba which was repaired without consequences.

Figure 3

(a) Preoperative X-ray pelvis, showing end on orientation of obturator foramen. (b) Postoperative X-ray pelvis, showing visible obturator foramen

DISCUSSION

Trendelenburg in 1906 stated that “All the patients of exstrophy are born with the potential of continence.”[13] Woodhouse and Kellett in 2006 stated that “All the patients of exstrophy bladder are born with the potential for fertility and continence.”[14] He also stated that the potential can be realized with proper reconstruction and potential may not survive the onslaught of surgery involved. In the functional reconstruction of bladder exstrophy, restoration of anatomy without add on additional morbidity is preferred to restore normal physiological function with preservation of continence and upper tract.[15]

For complete restoration of normal anatomy which also includes closure of pelvic ring, osteotomy is preferred over the methods without osteotomy for the reasons that within the reconstructed pelvic ring closed bladder is secured, base of levator ani is available to support the bladder base, length of corpora is not lost in corporoplasty. However, the reported incidence of complications, technical complexities, need for postoperative immobilization, and traction has always been a limiting factor to open the way for methods without osteotomy.[15] The abnormal bony configuration has been described by Sponseller et al. to emphasize 30% shortage of SPR with 18% outward rotation.[16] In this method, with selected pelvis configuration, we are addressing the issue of short SPR with superior pubic ramotomy and issue of outward rotation with the creation of hinge on the medial surface of ischial tuberosity. Hence approximation of pubic bone towards midline with bone holding forceps is automatically associated with inward rotation of IP ramus. Thus with bone holding forceps bringing pubic bone to midline, lengthening of SPR as well as inward rotation takes place which is responsible for conversion of trapezoid urogenital diaphragm to near triangular urogenital diaphragm, which indirectly offers additional length to midline corporoplasty as length of corpora is not lost in an endeavor to join them in midline dorsal to urethra. With this technique stretching and fatigue of muscles of adductor compartment is also affected, therefore once approximated with bone holding forceps, pubic bone, and linea alba do not fall apart even without the placement of fixator pins. Closure of pelvic ring and approximation of linea alba with this technique does not necessitate the immobilization or traction on the lower limb. Thus, postoperative maintenance of hygiene, cleanliness, and nursing is made much easier. In postoperative phase, despite baby moving limbs, pubic bone approximation and linea alba approximation stays in place. This fact is substantiated with 0% bladder dehiscence and 0% linea alba dehiscence in 85 cases of this report. In long-term follow-up of 13 years, no evidence of osteomyelitis, bone pain due to any nerve compression is noted. Application of this technique has been versatile through infancy to adolescence without any significant limitations. However, there is a limitation of the application of IP osteotomy to cases of CEB with different pelvic configuration. Patients with very wide pubic diastasis to the extent that the shape of the urogenital diaphragm between two IP ramus is the reverse trapezoid. In those cases in addition to IP osteotomy, transverse innominate osteotomy may also be needed, but by adhering to selection criteria of described configuration of the pelvis, IP osteotomy is an effective tool for the closure of pelvic ring without the additional incision, without the need of placement of fixator pins or limb immobilization.

CONCLUSIONS

The technique of IP osteotomy is effective for closure of pelvic ring in CEB with the specific pelvic configuration without the need of fixator pins, immobilization or additional skin incision with negligible morbidity.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.