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Anterior Innominate Osteotomy in Repair of Bladder Exstrophy
Paul D. Sponseller, MD; Mihir M. Jani, MD; Robert D. Jeffs, MD; John P. Gearhart, MD
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Investigation performed at the Johns Hopkins Medical Institutions, Baltimore, Maryland
Paul D. Sponseller, MD Mihir M. Jani, MD Robert D. Jeffs, MD John P. Gearhart, MD Division of Pediatric Orthopaedic Surgery (P.D.S. and M.M.J.), Department of Orthopaedic Surgery, and Division of Pediatric Urology (R.D.J. and J.P.G.), Department of Urology, Johns Hopkins Hospital and School of Medicine, 601 North Caroline Street, Baltimore, MD 21287-0882. E-mail address for P.D. Sponseller: psponse@jhmi.edu.
No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study.

The Journal of Bone & Joint Surgery.  2001; 83:184-184 
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Abstract

Background: Classic bladder exstrophy is a developmental defect presenting at birth with a wide pubic separation and an exposed bladder; cloacal exstrophy involves, in addition, intestinal prolapse. Reconstruction requires several surgical procedures. The use of anterior iliac osteotomies in this process has not been reviewed in a large series.

Methods: We reviewed the results of eighty-six anterior innominate osteotomies performed in conjunction with genitourinary repair of classic and cloacal bladder exstrophy in eighty-two patients. Clinical outcome measures were successful bladder closure, achievement of continence, and maintenance of a normal gait. Radiographs of the pelvis were reviewed, and the pubic intersymphyseal diastasis (a measure of the reduction in tension on the anterior closure) was measured preoperatively and at three time-points postoperatively. Children with classic exstrophy who had undergone osteotomy and bladder neck reconstruction but not bladder augmentation were divided into four groups on the basis of the degree of continence. In addition, children with classic exstrophy were stratified according to age at the time of the osteotomy. The mean postoperative percent reduction in the amount of the original diastasis was determined for all groups.

Results: Children with classic exstrophy and those with cloacal exstrophy had correction of the diastasis after the osteotomy, with greater correction in those with classic exstrophy, presumably because of better bone quality. Daytime continence was achieved with anterior osteotomy and bladder neck reconstruction in 74% of the children for whom continence was a goal. However, no difference in the symphyseal diastasis or in the percentage of pubic reduction was detected among the four continence groups. Children who were older at the time of the osteotomy maintained better correction over time. Wound dehiscence or bladder prolapse occurred in 4% of the patients who had osteotomy and primary closure, and the only important complication of the osteotomies was transient palsy of the left femoral nerve in seven children.

Conclusions: Anterior innominate osteotomy is an effective part of reconstructive repair of bladder exstrophy. The primary goals of the osteotomy are to reduce the tension in the closed bladder and the lower abdominal wall and to promote continence by restoring the sling of the pelvic floor muscles. These goals can be achieved in the majority of patients.

Figures in this Article
    The bladder exstrophy-epispadias complex is a congenital disorder that involves the genitourinary tract, the musculoskeletal system, and sometimes the intestinal tract. Classic bladder exstrophy involves the first two organ systems, whereas cloacal exstrophy involves all three. Exstrophy of the bladder results from abnormal anterior rupture of the cloacal membrane early in the embryonic period. Mesenchymal ingrowth into the abdominal wall is therefore inhibited. Since the pelvis is derived from sclerotomal components of the mesenchyme, the development of the pelvis may be affected by this altered migration of mesenchyme. Studies of the pathoanatomy of the pelvis in children with classic exstrophy have shown that, on each side, the posterior part of the pelvis is externally rotated about 12°, the acetabula are retroverted, and the pubic rami are 30% shorter than the normal length1. The prevalence of classic bladder exstrophy is approximately one per 40,000 children, whereas the prevalence of cloacal exstrophy is one per 200,000 children2,3. Children born with bladder exstrophy have an exposed bladder and a wide diastasis of the pubic rami resulting in an open pelvic ring. The musculoskeletal function appears to be normal throughout childhood; the gait is characterized by external foot progression, which lessens with growth1, even if osteotomy is not performed.
    Several types of pelvic osteotomies have been developed to help to close the pelvic ring and to decrease the stress on the abdominal wall during initial exstrophy closure and to improve the outcome of future genitourinary reconstruction2. Shultz was the first, as far as we know, to describe bilateral posterior iliac osteotomy as part of a two-stage repair of bladder exstrophy3. The earliest outcome studies of this osteotomy were done by O'Phelan4 and by Aadalen et al.5. This osteotomy has been shown to lower rates of wound dehiscence and to help to obtain a more secure and better genitourinary reconstruction than is obtained with reconstruction without osteotomy4,5. The success in achieving continence has been reported to be related to the reduction in the diastasis and has been thought to result from better approximation of the muscles of the pelvic floor around the urethra5.
    The sequence of bladder exstrophy reconstruction involves primary closure of the bladder and abdominal wall in the newborn period, epispadias repair around the age of one or two years in boys, and bladder neck reconstruction around the age of three or four, when the child is mature enough to maintain dryness. Patients may undergo pelvic osteotomy at one of these stages if the diastasis prevents attainment of these urologic goals. In general, we rarely perform osteotomy on newborns because the laxity of the sacroiliac ligaments allows closure of the defect without undue tension.
    Other types of osteotomies that have been used include bilateral osteotomy of the superior pubic ramus6-10, diagonal osteotomy of the iliac wing11, and anterior innominate osteotomy12, with or without posterior innominate osteotomy13. The anterior innominate osteotomy was developed for several reasons. The osteotomy is performed with the patient in the supine position as is the urologic repair, thus avoiding the need to turn the patient. The anterior osteotomy also allows placement of an external fixator under direct vision12. A greenstick-type closing-wedge osteotomy of the ilium is also performed adjacent to the sacrum in most patients who are more than two years old.
    We analyzed all pelvic osteotomies performed at our institution to assess the success of the combined procedure (osteotomy and urologic reconstruction) in achieving closure and continence and the degree to which the pubic diastasis was corrected and maintained. Since it was our impression that the children who had osteotomies early in life had less correction of the pubic diastasis as they grew, we examined the effect of age on the amount of final correction. In addition, we studied the relationship of diastasis correction to continence, as some surgeons have hypothesized that it is important to achieve approximation of the pelvic floor muscles to achieve good urinary continence. Finally, we assessed the complications of the osteotomies to gain a more complete picture of the costs as well as the benefits of this approach.
     
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    +Fig. 1-A:The anterior iliac osteotomy is performed about 5 to 10 mm proximal to the anterior inferior iliac spine in order to leave room for placement of the external fixator pins. It should intersect the most proximal part of the sciatic notch. The pins in the inferior segment should have purchase in both the medial and the lateral cortex.
     
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    +Fig. 1-B:Posterior osteotomy of the iliac wings is optional. The posterior cortex of the superior part of the ilium should be left intact.
     
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    +Fig. 1-C:Rotation of the pelvis after anterior and posterior iliac osteotomies.
     
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    +Fig. 1-D:Closure of the defect with suture repair of the symphysis. The sutures may be placed through bone or around the screws placed in the pubic rami.
     
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    +Fig. 2:Graph of the mean symphyseal diastases in patients with classic (open circles) and cloacal (closed diamonds) exstrophy at four time-points: (1) a few days before the osteotomy (preop), (2) within one week after the osteotomy (postop), (3) at the follow-up (F/U) examination approximately three months after the osteotomy and after removal of the fixator, and (4) at the latest follow-up examination (mean duration of radiographic follow-up, 3.5 years). Also shown is the estimated curve of symphyseal diastasis for patients with classic exstrophy (open squares) who had not undergone osteotomy1. Both the patients with classic exstrophy and those with cloacal exstrophy had correction after the anterior innominate osteotomy.
     
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    +Fig. 3-A:Figs. 3-A, 3-B, and 3-C Pelvic radiographs of a boy with classic exstrophy who was treated at our institution, at the age of four years, with bladder neck revision and bilateral combined anterior and posterior innominate osteotomy because of persistent incontinence. The patient had had primary closure with bilateral posterior iliac osteotomy as an infant at another institution and, later, had had epispadias repair and bladder neck reconstruction. Fig. 3-A Preoperative anteroposterior radiograph of the pelvis, showing a pubic diastasis of 7.5 cm.
     
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    +Fig. 3-B:Postoperative radiograph made ten days after combined anterior and posterior innominate osteotomy, demonstrating the positions of the fixator pins and the reduction of the diastasis to 1.1 cm (normal, 0.7 to 1 cm).
     
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    +Fig. 3-C:Radiograph of the pelvis made two and one-half years after the osteotomy, when the patient was six and one-half years old, showing complete healing of the osteotomy sites and a diastasis of 3.1 cm.
     
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    +Fig. 4-A:Figs. 4-A and 4-B Radiographs of the pelvis of a girl with cloacal exstrophy who was treated at our institution, at the age of twelve years, with genitourinary and cosmetic reconstruction of the pelvis, abdominal wall, and perineum. She had had primary closure with bilateral anterior innominate osteotomy at the age of five years at an outside institution. Fig. 4-A Preoperative radiograph showing a 14-cm pubic diastasis.
     
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    +Fig. 4-B:Pelvic radiograph made at the time of the latest radiographic follow-up, eighteen months postoperatively, showing a pubic diastasis of 2.0 cm.
     
    Anchor for JumpAnchor for JumpTABLE I:  Percentage of Correction of Diastasis with Respect to Age at Time of Surgery for Classic Exstrophy
    *The values are given as the mean and the standard deviation.
    Percentage of Pubic Approximation*Age at Time of Surgery
    0-6 mos (N = 23)>6-18 mos (N = 8)>18-24 mos (N = 9)>2-5 yrs (N = 21)>5 yrs (N = 11)
    At 3-mo follow-up examination42 ± 4067 ± 1462 ± 1566 ± 1567 ± 27
    At latest follow-up examination-8 ± 4817 ± 1440 ± 1843 ± 2147 ± 29
    We reviewed the cases of all of the children in whom anterior innominate osteotomy was performed as part of reconstructive surgery of the bladder exstrophy complex at our institution from 1988 to 1996. A total of ninety-two bilateral anterior innominate osteotomies (with or without posterior osteotomies) were performed in eighty-eight children. Four repeat osteotomies were performed because of failure of the primary closure and a need for reapproximation at the time of bladder neck reconstruction in two patients each. Of the eighty-eight children, four had less than two years of follow-up and two were lost to follow-up. The remaining eighty-two children were included in the study. Ten of these children had cloacal exstrophy and seventy-two, classic exstrophy. The mean age (and standard deviation) at the time of the operation was 2.9 3.7 years (range, birth to thirteen years), and all patients had at least two years (mean, 4.8 years) of clinical follow-up. Thirty-eight procedures (thirty-six in patients who had classic exstrophy and two in patients who had cloacal exstrophy) consisted of anterior osteotomies only, and forty-eight (forty in patients who had classic exstrophy and eight in patients who had cloacal exstrophy) consisted of anterior and posterior osteotomies. Data on the bilateral osteotomies in the eighty-two patients were analyzed as described below.
    Twenty-nine children who had had primary closure of the defect (with a pelvic osteotomy in twenty and without it in nine) had wound dehiscence and/or bladder prolapse and presented for repeat closure. (In all cases in which bladder prolapse occurred, the pelvic diastasis recurred.) Ten of these patients underwent anterior osteotomies only, and nineteen had combined anterior and posterior osteotomies. We performed innominate osteotomy with initial exstrophy closure in twenty-one infants (fourteen had anterior osteotomies only and seven, anterior and posterior osteotomies) who were first seen at our institution. Thirty children had osteotomies at the time of reconstruction of the bladder neck to restore continence because they had a wide diastasis and they lacked a firm fibrocartilaginous bar from which to suspend the bladder neck. In addition, three children had anterior osteotomies as part of an epispadias repair and three had perineal or abdominal wall reconstruction with anterior and posterior innominate osteotomies. As four patients required repeat osteotomies, eighty-six procedures were performed on eighty-two patients.

    Technique of Anterior Innominate Osteotomy

    Anterior innominate osteotomy is performed by first placing the patient in the supine position, preparing and draping the lower part of the body below the costal margin, and placing absorbent gauze with a sterile barrier drape over the exposed bladder. Oblique incisions are made inferior to the anterior superior iliac spine as described for the Salter osteotomy12,14 (Fig. 1-AFigs. 1-A, Fig. 1-B, Fig. 1-C, and Fig. 1-D). The femoral nerve is exposed by incising the fascia superficial to it. Each side of the pelvis is exposed subperiosteally from the iliac wings inferiorly to the pectineal tubercle and posteriorly to the sacroiliac joint. The periosteum of the sciatic notch is elevated carefully, and a Gigli saw is used to create a transverse iliac osteotomy, exiting anteriorly at a point halfway between the anterior superior and anterior inferior spines. This osteotomy is created at a slightly more cephalad level than that described for a Salter osteotomy, in order to allow placement of external fixator pins in the distal segments.
    For patients who are more than two years old or who have cloacal exstrophy, an additional osteotomy of the posterior part of the ilium may be performed through the anterior approach to facilitate complete correction of the deformity. This step is important because anatomical studies have shown that the posterior portion of the pelvis is externally rotated in patients with exstrophy, and older patients lose the elasticity of the sacroiliac ligaments1. We believe that failure to correct the external rotation of the iliac wings in these patients results in tightening of the inguinal ligament over the femoral nerve as the pubic diastasis is narrowed. This region may be approached by continuing the subperiosteal dissection of the medial surface of the iliac wing posteriorly to the sacroiliac joint. Often there is a nutrient vessel to the ilium in the middle of the wing, and bleeding from this vessel should be controlled with cautery or bone wax. A rongeur or a burr is then used to create a closing-wedge osteotomy vertically (longitudinally) by removing cortical and cancellous bone from the anterior portion of the ilium just lateral to the sacroiliac joint13. The osteotomy should be performed at least a centimeter away from the sacroiliac joint. The sclerotic cortical bone proximal to the sciatic notch should be divided completely. The more pliable proximal part of the posterior iliac cortex is left intact and used as a hinge. This combination of osteotomies corrects the abnormalities in both the anterior and the posterior part of the pelvis.
    Two threaded fixator pins are placed in the inferior pelvic segment, and two pins are placed in the wing of the ilium superiorly. An anteroposterior radiograph of the pelvis is made to confirm pin placement, soft tissues are closed, and the urologic procedure is then performed. At the end of the procedure, in order to cover the repaired bladder, the pelvis is closed with a horizontal mattress suture placed within the pubic bone on each side. In patients who were more than about eight years old, we recently used supplemental internal fixation across the diastasis. The fixation device consists of a two-hole plate, with one screw directed from medial to lateral in the medullary canal of each superior pubic ramus (Fig. 4-BFig. 4-B). This helps to achieve and to maintain correction in these most difficult cases. The lower abdominal wall muscles then are closed, and external fixator bars are applied between the pins to hold the pelvis in the corrected position.
    Postoperatively, patients remain supine with the lower extremity in light skin traction for approximately four weeks to prevent dislodgment of the vesicostomy tubes and destabilization of the pelvis. If radiographs made seven to ten days postoperatively do not show complete reduction of the symphyseal diastasis, it can be gradually approximated with use of the fixator bars over several days. The external fixator is left in place for approximately six weeks, until adequate callus is seen at the osteotomy sites12,13. In newborns, the pelvic bones may be too soft to allow secure pin fixation, and only skin traction, with the hips flexed to 90 and adducted to the midline, is used.

    Radiographic Analysis

    Symphyseal diastasis was measured at four time-points: (1) at the examination performed a few days before the surgery (preoperative), (2) on the first radiograph made within one week after the surgery (postoperative), (3) at three months after the osteotomy (six weeks after removal of the external fixator), and (4) at the time of the latest follow-up. The diastasis was determined by measuring the distance between the two most medial points of the pubic rami. The hips were examined for any evidence of dysplasia, and the osteotomy sites were examined for healing.
    The percentage of pubic approximation was calculated according to the following formula:
    Image Not Available
    The denominator in the equation is corrected for the 1-cm symphyseal diastasis that is present throughout life in normal individuals (unpublished data, 1990). The measurements of the diastasis at the three-month and latest follow-up evaluations were used for the "postoperative diastasis" in the formula. In patients who required repeat osteotomy, only the results of the last procedure were analyzed because this procedure had the longest duration of follow-up.

    Degree of Continence and Percentage of Pubic Approximation

    Thirty-eight children with classic exstrophy who had undergone bladder neck reconstruction but not bladder augmentation and/or stoma construction and thus could voluntarily void through a reconstructed urethra were stratified, according to the level of continence, into four categories: excellent (dry during the day and at night, with occasional stress incontinence), good (dry for more than three hours during the day and wet at night), fair (dry for two to three hours), and poor (dry for less than two hours).
    The mean percentage of pubic approximation and the mean pubic diastasis were calculated at three months and at the final follow-up evaluation for each continence group. In addition, the same analysis was performed to compare the patients with excellent and good continence as a combined group with those with fair and poor continence as a combined group.

    Age at the Time of the Osteotomy and Percentage of Pubic Approximation

    Patients with classic exstrophy were stratified into five groups according to the age at the time of the osteotomy: (1) birth to six months, (2) more than six months to eighteen months, (3) more than eighteen months to twenty-four months, (4) more than two years to five years, and (5) more than five years. The wide spectrum of ages at the time of the operation reflects the various problems that were addressed: initial closure, revision of failed closure, bladder neck reconstruction, or perineal reconstruction. The mean percentage of pubic approximation (as described above) and the mean diastasis at three months and at the time of the final follow-up were determined for each age-group.

    Gait and Motor Examination

    At the most recent examination, patients were observed while they were walking to determine whether they had a limp. In addition, the parents were questioned about whether the child had any pain in the pelvis or lower extremities, any limitation in running or playing, or a limp during these activities.
    Statistical analysis was done with use of two-sample t tests for groups with unequal variance. The level of significance was set at p < 0.05.

    Surgical Outcome and Complications

    The mean estimated blood loss (and standard deviation) was 120 ± 106 ml for anterior innominate osteotomies alone and 176 ± 114 ml for anterior and posterior osteotomies. The mean total time that the external fixator was worn was 6.1 ± 1.6 weeks. For the eighty children (eighty-four procedures) who had traction in addition to external fixation, the mean time in traction was 4.3 ± 1.3 weeks. For the two newborns for whom external fixation was not considered appropriate and who were treated with traction only, the time in traction was three and four weeks.
    Postoperative complications included transient palsy of the left femoral nerve, which resolved at a mean of twelve weeks postoperatively, in seven patients. This complication occurred after anterior innominate osteotomy in five patients and after combined anterior and posterior innominate osteotomies in two patients. This difference reached significance (p = 0.04). None of the patients had palsy of the right femoral nerve, although the same surgeon performed the same technique on both sides. The palsies all resolved spontaneously and fully. The patients were managed with bed rest for the first six to eight weeks, and then they wore a knee-immobilizer for the remaining six to eight weeks until quadriceps weakness resolved.
    Other complications included delayed union of the anterior iliac osteotomy site (three patients), superficial infection at the site of the iliofemoral incision that required irrigation and d�bridement (one patient), transient abductor weakness in the right thigh (one patient), an infection around a pin in the ilium that required irrigation and d�bridement (one patient), and transient motor palsy involving the right peroneal nerve (one patient). In addition, one child had a persistent, mild left Trendelenburg gait of unknown cause (see below). Postoperative skin inflammation occurred commonly around the fixator pins, and it was usually controlled with oral antibiotics.
    One child had bladder prolapse after bilateral anterior and posterior innominate osteotomies and primary closure. Wound dehiscence developed after primary closure and pelvic osteotomy in another child when he had a respiratory syncytial virus infection, which caused severe respiratory distress with labored, abdominal breathing. These were considered failures of closure with anterior innominate osteotomy. Both patients had classic exstrophy.
    Four patients in our study required repeat osteotomies, which we performed. All had had the initial osteotomies before the first year of life. In addition to the two patients in whom the closures failed (as described above), two others, in whom the defect had been closed when they were infants, had development of a diastasis and lacked a firm bar of symphyseal tissue from which to suspend the bladder neck at the time of bladder neck reconstruction. Therefore, repeat osteotomies were performed concomitantly at the suggestion of the urologist. No particular technical difficulties were encountered during these repeat osteotomies or during those performed after an osteotomy done at another hospital, except for increased difficulty in isolating the superficial cutaneous branch of the femoral nerve.

    Symphyseal Diastasis

    The mean symphyseal diastasis at each time-point in the patients with classic exstrophy and those with cloacal exstrophy is shown in Figure 2Figure 2. Both the patients who had classic exstrophy and those who had cloacal exstrophy had a decrease in the symphyseal diastasis after the surgery, although those with classic exstrophy obtained greater correction toward normal (Fig. 3-AFigs. 3-A, Fig. 3-B3-B, and Fig. 3-C3-C). Patients with classic exstrophy had a mean diastasis (and standard deviation) of 5.1 ± 1.2 cm preoperatively, which was corrected to 1.8 ± 0.6 cm postoperatively and measured 2.5 ± 0.8 cm at three months postoperatively and 3.7 ± 1.1 cm at the time of the latest follow-up (mean, 4.8 years). Patients with cloacal exstrophy had a mean diastasis of 8.1 ± 3 cm preoperatively, which was corrected to 2.7 ± 1.4 cm postoperatively and measured 4.5 ± 1.2 cm at three months postoperatively and 5.8 ± 3.4 cm at the time of the latest follow-up (mean, 4.6 years). The goal of relaxing the tension on the midline repair and allowing successful closure of the bladder and lower abdominal wall was achieved in all of the patients with cloacal exstrophy (Fig. 4-AFigs. 4-A and Fig. 4-B4-B).

    Continence and Diastasis

    Of the patients with classic exstrophy who had undergone osteotomy and bladder neck reconstruction but not bladder augmentation, and therefore for whom continence was a goal, seventeen had excellent continence; eleven, good; seven, fair; and three, poor. The patients with excellent continence had a mean correction of the diastasis (and standard deviation) of 63% ± 18% at three months and 37% ± 22% at the time of the latest follow-up. The patients with good continence had a mean correction of 62% ± 33% at three months and 24% ± 45% at the time of the latest follow-up. The patients with fair continence had a mean correction of 64% ± 18% at three months and 41% ± 17% at the time of the final follow-up. The patients who had poor continence had a mean correction of 79% ± 13% at three months and 53% ± 29% at the time of the final follow-up. With the numbers available, there was no significant difference among any of the groups, stratified according to the degree of continence, with respect to the mean diastasis or the percentage of correction of symphyseal diastasis (at either time-point). In addition, there was no significant difference in the mean diastasis or the percentage of correction when the patients with excellent and good continence as a combined group were compared with the patients with fair and poor continence as a combined group. None of the patients had increasing reflux of urine into the ureters or more than one urinary tract infection per year.

    Age at the Time of the Osteotomy and Percentage of Pubic Approximation

    The percentage of approximation of the pubic diastasis with respect to the age of the patient at the time of the operation is presented in Table ITable I. At the three-month follow-up examination, there was significantly less correction in the birth to six-month age-group than in the two to five-year age-group (p < 0.05). At the time of the latest follow-up, the group that had the operation between birth and six months had significantly less correction than the group that had the operation between six and eighteen months (p < 0.05) and all other age-groups (p < 0.001); in addition, the group that had the operation at six to eighteen months had significantly less correction than the group that was eighteen to twenty-four months old (p < 0.05), the group that was two to five years old (p < 0.01), and the group that was more than five years old at the time of the operation (p < 0.02). There was no difference among the groups with respect to the duration of follow-up.

    Gait and Motor Examination

    One patient had a persistent unilateral Trendelenburg gait at the time of the final follow-up, at three years. He had palpable contraction of the gluteus medius and minimus muscle group, but active abduction of the hip against gravity was one-half grade below normal. This may have been due to an injury to the superior gluteal nerve, as no osseous abnormality was found. All of the patients with a femoral nerve palsy and the one patient with a peroneal nerve palsy had complete restoration of strength within three months. The parents of two of the children complained of a persistent so-called out-toeing gait when their children were three and four years old. All children with classic exstrophy were able to run and to participate in sports to the same degree as preoperatively. No patient complained of pain in the pelvis, hips, or lower extremities at the latest follow-up examination.
    Pelvic osteotomy has been widely accepted as a useful adjunct in the operative treatment of bladder exstrophy. The anterior approach, used in the present report15, obviates the need to turn the patient and allows external fixation to be applied under direct vision.
    Both the children with classic exstrophy and those with cloacal exstrophy had correction of the degree of bone and soft-tissue diastasis following osteotomy, although the patients with classic exstrophy gained more correction. Two of forty-nine children who underwent anterior innominate osteotomy with primary closure had wound dehiscence or bladder prolapse, resulting in a failure rate of 4%, which is similar to the results reported with posterior osteotomy5. When repeat bladder closure was performed with an osteotomy, which represented 43% of all bladder closures done at our institution, there were no failures.
    The most common complication was transient palsy of the left femoral nerve, probably resulting from femoral nerve compression between the iliacus muscle and the inguinal ligament. We believe that the inguinal ligament becomes stretched and its direction changes with rotation of the inferior iliac segment, which includes its pubic insertion. The medial portion of this more taut inguinal ligament also appears to be translated slightly posteriorly. After we had formulated this hypothesis, we added a posterior osteotomy to the procedure in order to allow internal rotation of the iliac wings and to decrease the stretch of the inguinal ligament. We also now expose the femoral nerve and carefully incise the taut, cordlike fold of the external oblique muscle, which forms the inguinal ligament. These two steps seem to have decreased the rate of femoral nerve palsy. No femoral arterial or venous compromise was seen. We are unsure why femoral nerve palsy occurred only on the left.
    In a study of posterior iliac osteotomies, Aadelen et al. reported that asymmetrical closure and vertical migration of one hemipelvis was an occasional problem, with a functional limb-length inequality of more than 2 cm seen in 6% of 100 patients5. With the anterior approach, we have not observed this problem. This is most likely because the primary plane of the osteotomy is transverse, with a broad metaphyseal contact area to resist vertical migration. In older children in whom we add a posterior vertical osteotomy, it is done in a so-called greenstick fashion, preserving the proximal part of the posterior iliac cortex to maintain posterior stability.
    Aadalen et al. found that the mean interpubic distance in thirty-six children who underwent primary closure and bilateral posterior iliac osteotomy before three years of age was substantially less in those who had an excellent or good result than in those who had a fair or poor result5. However, the percentage of excellent or good results in that study (45%) was less than that in our study. We found no association between the degree of continence and the pubic diastasis or the percentage of pubic approximation in children who underwent pelvic osteotomy. However, of the thirty-eight children in the study who underwent anterior osteotomy and bladder neck reconstruction only, twenty-eight (74%) were able to maintain excellent or good continence (dry for more than three hours during the day). Our working theory was that pelvic closure by osteotomy promotes continence by bringing the muscles of the pelvic floor together to help to place the urethra within the pelvis and thus provide a more acute ureterovesical angle. It also allows the urethra to be surrounded by the restored sling of the pelvic floor muscles2. Our results suggest that the amount of closure achieved with anterior innominate osteotomy and eventual bladder neck reconstruction is not associated with continence. Since the correction of the diastasis by itself was not associated with continence, we cannot determine whether the osteotomy or the bladder neck reconstruction is responsible for the high degree of success. Multiple factors, such as the age at follow-up, bladder size, and number or type of surgical procedures, may confound the analysis and would require study of a larger number of patients. On the basis of the results in the present study, we now perform osteotomy only if the patient lacks a firm symphyseal bar of bone or fibrocartilaginous tissue from which to suspend the bladder neck.
    The age of the patient plays a role in the amount of correction that is maintained over time, as older children tend to retain a greater amount of correction. It is our impression that partial recurrence of the diastasis occurs by two mechanisms. First, the pelvis may partially derotate as a result of early loosening of the pin-bone purchase before the osteotomy site heals; this is seen mostly in infants. Second, there is long-term undergrowth of the ischiopubic segment (which has been shown to be 33% smaller than normal in adults with exstrophy1) as the whole pelvis grows. The amount of pubic diastasis increased linearly with growth in patients with uncorrected exstrophy.
    We regard the main role of osteotomy to be relaxation of the tension on the bladder and the repaired abdominal wall during wound-healing. Therefore, we rarely do an osteotomy in newborns and young infants whose ligamentous laxity allows the pelvis to be closed without much tension. In patients with cloacal exstrophy, we often defer closure until bone density is sufficient to permit good pin fixation to buttress the closure (when the patient is eighteen to twenty-four months old). A secondary goal is to improve the appearance of the widened perineum. In patients for whom improved appearance is the primary goal, we recommend delaying the osteotomy until the age of about eight years to minimize the chance of correction being lost.
    In summary, the ideal age for osteotomies is related to the urologic goal to be achieved. An osteotomy is not performed in newborns, unless there has been failure of primary closure. In all older patients, it is performed to facilitate primary closure or reclosure, usually in the three to five-year age-group. We now perform anterior and posterior osteotomies together in all patients who are more than two years old. The primary goals of anterior innominate osteotomy in patients with exstrophy are to reduce the tension in the closed bladder and the abdominal wall and possibly to promote continence by restoring the fibrous symphyseal bar and the pelvic floor muscles. These goals can be achieved in the majority of patients.
    Note: The authors thank Hong Cui, MD, for the illustrations.
    Sponseller PD; Bisson LJ; Gearhart JP; Jeffs RD; Magid D; and Fishman E: The anatomy of the pelvis in the exstrophy complex. J Bone Joint Surg Am,1995.77: 177-89, 77177  1995  [PubMed]
     
    Jeffs RD; Guice SL; and Oesch I: The factors in successful exstrophy closure. J Urol.,1982.127: 974-6, 127974  1982  [PubMed]
     
    Shultz WG: Plastic repair of exstrophy of bladder combined with bilateral osteotomy of ilia. J Urol,1958.79: 453-8, 79453  1958  [PubMed]
     
    O'Phelan EH: Iliac osteotomy in exstrophy of the bladder. J Bone Joint Surg Am,1963.45: 1409-22, 451409  1963  [PubMed]
     
    Aadalen RJ; O'Phelan EH; Chisholm TC; McParland FA Jr; and Sweetser TH Jr: Exstrophy of the bladder: long-term results of bilateral posterior iliac osteotomies and two-stage anatomic repair. Clin Orthop,1980.151: 193-200, 151193  1980  [PubMed]
     
    Frey P: Bilateral anterior pubic osteotomy in bladder exstrophy closure. J Urol,1996.156(2 Pt 2): 812-5, 156(2 Pt 2)812  1996 
     
    Frey P, and Cohen SJ: Bladder exstrophy-anterior osteotomy of the pelvis-a new surgical technic for facilitating stabilization of the pelvis and abdominal closure. Z Kinderchir,1988.43: 171-3, German43171  1988  [PubMed]
     
    Frey P, and Cohen SJ: Anterior pelvic osteotomy. A new operative technique facilitating primary bladder exstrophy closure. Br J Urol,1989.64: 641-3, 64641  1989  [PubMed]
     
    Perovic S; Brdar R; and Scepanovic D: Bladder exstrophy and anterior pelvic osteotomy. Br J Urol,1992.70: 678-82, 70678  1992  [PubMed]
     
    Schmidt AH; Keenen TL; Tank ES; Bird CB; and Beals RK: Pelvic osteotomy for bladder exstrophy. J Pediatr Orthop,1993.13: 214-9, 13214  1993  [PubMed]
     
    McKenna PH; Khoury AE; McLorie GA; Churchill BM; Babyn PB; and Wedge JH: Iliac osteotomy: a model to compare the options in bladder and cloacal exstrophy reconstruction. J Urol,1994.151: 182-6, 151182  1994  [PubMed]
     
    Sponseller PD; Gearhart JP; and Jeffs RD: Anterior innominate osteotomies for failure or late closure of bladder exstrophy. J Urol,1991.146: 137-40, 146137  1991  [PubMed]
     
    Gearhart JP, Forschner DC, Jeffs RD, Ben-Chaim J, Sponseller PD.: A combined vertical and horizontal pelvic osteotomy approach for primary and secondary repair of bladder exstrophy. J Urol,1996.155: 689-93, 155689  1996  [PubMed]
     
    Salter RB, and Dubos JP: The first fifteen years' personal experience with innominate osteotomy in the treatment of congenital dislocation and subluxation of the hip. Clin Orthop,1974.98: 72-103, 9872  1974  [PubMed]
     
    Watts H. Double anterior osteotomies of the pelvis for exstrophy of the bladder. Read at the Annual Meeting of the Pediatric Orthopaedic Society of North America; 1988 May 9; Colorado Springs, CO 
     

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    Anchor for JumpAnchor for Jump
    +Fig. 1-A:The anterior iliac osteotomy is performed about 5 to 10 mm proximal to the anterior inferior iliac spine in order to leave room for placement of the external fixator pins. It should intersect the most proximal part of the sciatic notch. The pins in the inferior segment should have purchase in both the medial and the lateral cortex.
    Anchor for JumpAnchor for Jump
    +Fig. 1-B:Posterior osteotomy of the iliac wings is optional. The posterior cortex of the superior part of the ilium should be left intact.
    Anchor for JumpAnchor for Jump
    +Fig. 1-C:Rotation of the pelvis after anterior and posterior iliac osteotomies.
    Anchor for JumpAnchor for Jump
    +Fig. 1-D:Closure of the defect with suture repair of the symphysis. The sutures may be placed through bone or around the screws placed in the pubic rami.
    Anchor for JumpAnchor for Jump
    +Fig. 2:Graph of the mean symphyseal diastases in patients with classic (open circles) and cloacal (closed diamonds) exstrophy at four time-points: (1) a few days before the osteotomy (preop), (2) within one week after the osteotomy (postop), (3) at the follow-up (F/U) examination approximately three months after the osteotomy and after removal of the fixator, and (4) at the latest follow-up examination (mean duration of radiographic follow-up, 3.5 years). Also shown is the estimated curve of symphyseal diastasis for patients with classic exstrophy (open squares) who had not undergone osteotomy1. Both the patients with classic exstrophy and those with cloacal exstrophy had correction after the anterior innominate osteotomy.
    Anchor for JumpAnchor for Jump
    +Fig. 3-A:Figs. 3-A, 3-B, and 3-C Pelvic radiographs of a boy with classic exstrophy who was treated at our institution, at the age of four years, with bladder neck revision and bilateral combined anterior and posterior innominate osteotomy because of persistent incontinence. The patient had had primary closure with bilateral posterior iliac osteotomy as an infant at another institution and, later, had had epispadias repair and bladder neck reconstruction. Fig. 3-A Preoperative anteroposterior radiograph of the pelvis, showing a pubic diastasis of 7.5 cm.
    Anchor for JumpAnchor for Jump
    +Fig. 3-B:Postoperative radiograph made ten days after combined anterior and posterior innominate osteotomy, demonstrating the positions of the fixator pins and the reduction of the diastasis to 1.1 cm (normal, 0.7 to 1 cm).
    Anchor for JumpAnchor for Jump
    +Fig. 3-C:Radiograph of the pelvis made two and one-half years after the osteotomy, when the patient was six and one-half years old, showing complete healing of the osteotomy sites and a diastasis of 3.1 cm.
    Anchor for JumpAnchor for Jump
    +Fig. 4-A:Figs. 4-A and 4-B Radiographs of the pelvis of a girl with cloacal exstrophy who was treated at our institution, at the age of twelve years, with genitourinary and cosmetic reconstruction of the pelvis, abdominal wall, and perineum. She had had primary closure with bilateral anterior innominate osteotomy at the age of five years at an outside institution. Fig. 4-A Preoperative radiograph showing a 14-cm pubic diastasis.
    Anchor for JumpAnchor for Jump
    +Fig. 4-B:Pelvic radiograph made at the time of the latest radiographic follow-up, eighteen months postoperatively, showing a pubic diastasis of 2.0 cm.
    Anchor for JumpAnchor for JumpTABLE I:  Percentage of Correction of Diastasis with Respect to Age at Time of Surgery for Classic Exstrophy
    *The values are given as the mean and the standard deviation.
    Percentage of Pubic Approximation*Age at Time of Surgery
    0-6 mos (N = 23)>6-18 mos (N = 8)>18-24 mos (N = 9)>2-5 yrs (N = 21)>5 yrs (N = 11)
    At 3-mo follow-up examination42 ± 4067 ± 1462 ± 1566 ± 1567 ± 27
    At latest follow-up examination-8 ± 4817 ± 1440 ± 1843 ± 2147 ± 29
    Sponseller PD; Bisson LJ; Gearhart JP; Jeffs RD; Magid D; and Fishman E: The anatomy of the pelvis in the exstrophy complex. J Bone Joint Surg Am,1995.77: 177-89, 77177  1995  [PubMed]
     
    Jeffs RD; Guice SL; and Oesch I: The factors in successful exstrophy closure. J Urol.,1982.127: 974-6, 127974  1982  [PubMed]
     
    Shultz WG: Plastic repair of exstrophy of bladder combined with bilateral osteotomy of ilia. J Urol,1958.79: 453-8, 79453  1958  [PubMed]
     
    O'Phelan EH: Iliac osteotomy in exstrophy of the bladder. J Bone Joint Surg Am,1963.45: 1409-22, 451409  1963  [PubMed]
     
    Aadalen RJ; O'Phelan EH; Chisholm TC; McParland FA Jr; and Sweetser TH Jr: Exstrophy of the bladder: long-term results of bilateral posterior iliac osteotomies and two-stage anatomic repair. Clin Orthop,1980.151: 193-200, 151193  1980  [PubMed]
     
    Frey P: Bilateral anterior pubic osteotomy in bladder exstrophy closure. J Urol,1996.156(2 Pt 2): 812-5, 156(2 Pt 2)812  1996 
     
    Frey P, and Cohen SJ: Bladder exstrophy-anterior osteotomy of the pelvis-a new surgical technic for facilitating stabilization of the pelvis and abdominal closure. Z Kinderchir,1988.43: 171-3, German43171  1988  [PubMed]
     
    Frey P, and Cohen SJ: Anterior pelvic osteotomy. A new operative technique facilitating primary bladder exstrophy closure. Br J Urol,1989.64: 641-3, 64641  1989  [PubMed]
     
    Perovic S; Brdar R; and Scepanovic D: Bladder exstrophy and anterior pelvic osteotomy. Br J Urol,1992.70: 678-82, 70678  1992  [PubMed]
     
    Schmidt AH; Keenen TL; Tank ES; Bird CB; and Beals RK: Pelvic osteotomy for bladder exstrophy. J Pediatr Orthop,1993.13: 214-9, 13214  1993  [PubMed]
     
    McKenna PH; Khoury AE; McLorie GA; Churchill BM; Babyn PB; and Wedge JH: Iliac osteotomy: a model to compare the options in bladder and cloacal exstrophy reconstruction. J Urol,1994.151: 182-6, 151182  1994  [PubMed]
     
    Sponseller PD; Gearhart JP; and Jeffs RD: Anterior innominate osteotomies for failure or late closure of bladder exstrophy. J Urol,1991.146: 137-40, 146137  1991  [PubMed]
     
    Gearhart JP, Forschner DC, Jeffs RD, Ben-Chaim J, Sponseller PD.: A combined vertical and horizontal pelvic osteotomy approach for primary and secondary repair of bladder exstrophy. J Urol,1996.155: 689-93, 155689  1996  [PubMed]
     
    Salter RB, and Dubos JP: The first fifteen years' personal experience with innominate osteotomy in the treatment of congenital dislocation and subluxation of the hip. Clin Orthop,1974.98: 72-103, 9872  1974  [PubMed]
     
    Watts H. Double anterior osteotomies of the pelvis for exstrophy of the bladder. Read at the Annual Meeting of the Pediatric Orthopaedic Society of North America; 1988 May 9; Colorado Springs, CO 
     
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