Pelvic Osteotomies for Cloacal Exstrophy

Cloacal exstrophy is part of a wide-ranging spectrum of rare congenital abnormalities resulting from the same embryological defect. Conditions include bladder exstrophy, epispadias, cloacal exstrophy, omphalocele, and more. Mortality due to complications with cloacal exstrophy was historically significant as it is among the most severe of these abnormalities. However, advancements in reconstructive surgery have improved the survival of patients. Pelvic osteotomy is typically indicated in cloacal exstrophy as it normally presents with widely separated pubic bones that require approximation as part of abdominal wall closure.

The omphalocele, exstrophy of the cloaca, imperforate anus, and spinal defects (OEIS) complex is rare, affecting 1 in 200,000 to 400,000 pregnancies. There may be a spectrum of defects ranging from penile epispadias, through bladder and cloacal exstrophy.¹ 

In nearly all cloacal exstrophy patients, spinal cord or vertebral abnormalities are seen. Orthopedic deformities also include a widely separated pubic symphysis and varying degrees of limb abnormalities.² Pelvic osteotomy as seen in this case is indicated to remedy pubic deformities as part of the treatment course for cloacal exstrophy.

The patient was one of two twins. The other twin presented with no cloacal or congenital abnormalities. Prenatal ultrasound detected cloacal exstrophy with associated myelomeningocele. 

Prenatal ultrasound findings can be suggestive of defects of the exstrophy-epispadias complex. Cloacal exstrophy will be visible upon birth in the delivery room. Patients are often preterm. As many as 65% of patients will present with clubfoot, and as many as 80% of patients have vertebral abnormalities. Myelodysplasia is very commonly seen in cloacal exstrophy patients.³

Omphaloceles are present in nearly all cloacal exstrophy patients. The bladder will be open and separated into two halves that flank the exposed interior of the cecum. Exposed bladder plate with a wide diastasis of the pubic rami can be seen. 

Early diagnosis of the OIES complex is now possible using prenatal ultrasound. A prolapsed ileal segment unique to cloacal exstrophy may be visualized as an “elephant trunk like” mass on ultrasound. Major diagnostic criteria include non-visualization of the bladder, a large midline infraumbilical anterior wall defect, cystic anterior wall structure, omphalocele, and myelomeningocele.⁴ Minor diagnostic criteria include lower extremity defects, renal anomalies, ascites, widened pubic arches, narrow thorax, hydrocephalus, and single umbilical artery.⁴ CT or MRI can be used to obtain more detailed imaging prior to surgery to determine the best surgical plan.⁴

Anterior oblique osteotomy was the technique used in this case. Traditionally, osteotomies have been posterior, transverse, or a combination of the two. However, anterior has been shown to be more favorable. Posterior iliac osteotomy is an extensive procedure requiring rotating the patient from the prone to supine position intraoperatively whereas an anterior osteotomy can be performed with the patient in supine position throughout the procedure. Anterior osteotomy was associated with a closer reduction of the symphyseal diastasis and lower rates of recurrence of separation in pubic diastasis.^5,6 The anterior oblique iliac osteotomy requires only a modest dissection of tissue allowing for less blood loss and a lower risk of infection and vascular and neurologic lesions.⁷

Other techniques of reducing pubic diastasis include the oblique iliac wing osteotomy or a pubic ramotomy. The oblique iliac wing osteotomy shows promise as a technique but has not been widely tested at this time. Pubic ramotomy has been shown to inadequately restore pelvic osseous relations, except in female newborns, and is therefore not widely used.^3,7 

Modern treatment of cloacal exstrophy will involve an anterior pelvic osteotomy facilitating the success of urogenital reconstructive surgery. This involves reduction of the pubic diastasis to restore normal bladder, urethra, and pelvic floor muscle anatomy.⁷ The goals of the modern treatment of cloacal exstrophy include secure abdominal and bladder closure, preservation of renal function, achievement of satisfactory continence, functional genitalia, and prevention of short bowel syndrome.^8, 9

Severe pulmonary hypoplasia has been noted as a contraindication.¹⁰ In cases where there is an extremely wide pubic diastasis of >6 cm or if the patient has previously failed a primary closure, osteotomy may be more effective if performed prior to a secondary procedure for abdominal wall closure.⁸

Pubic bone approximation is a requirement for a successful bladder and abdominal wall closure for patients with cloacal exstrophy, thereby necessitating a pelvic osteotomy. Pelvic osteotomy allows for a deeper placement of the bladder in the pelvis and reduces abdominal wall tension.¹¹ Most patients who do not undergo osteotomy at the time of cloacal closure require a secondary closure.⁸

A key point in successful cloacal exstrophy closure is to have a tension-free approximation of the widely separated public bones and anterior abdominal wall. To maintain closure and prevent said tension from altering the bladder neck and neourethral closure, secure pelvic ring closure, and postoperative traction or external fixation is needed regardless of the method of the osteotomy. Prevention of shearing forces from affecting those areas allows the bladder to remain deeper in the pelvis behind the anterior pelvic closure and lowers the risk of dehiscence of the wound and extrusion of the bladder.⁸

The anterior osteotomy approach has several advantages over the traditional approaches, including better approximation and mobility of the pubic rami at the time of closure and no requirement for turning the patient during the operation. Adjunctive posterior osteotomy can be included as needed from the anterior approach for cases of prior failed closure or extreme diastasis of >6 cm.^3, 8 These cases may also benefit from a staged procedure rather than completing the osteotomy at the same time as the exstrophy closure. The patient’s pelvis would be brought together with slow stretching of the pelvic soft tissue and lead to fewer complications and less blood loss at the time of closure.¹¹

Anterior osteotomy may be preferred over posterior in cases of severe lumbosacral dysraphism due to the proximity of incision to that of the often present myelomeningocele defect.³ Lumbar dysraphism has a high incidence rate in cloacal exstrophy patients, and most patients will require multiple later surgical procedures to achieve adequate bladder capacity and continence. While continence is part of the end goal of treatment, a direct and definitive relationship between pubic symphyseal closure and continence has not been established as the structures related to continence continue to evolve over time postosteotomy and lead to the need for subsequent procedures.^4, 5

Complications can include dehiscence, bladder prolapse, and ventral herniation. Firm and tension-free closure is important to mitigate the odds of these complications.⁸ Femoral nerve palsies are another potential complication but are usually transient. Avoiding this can be facilitated by carefully elevating the superior gluteal nerve and vessels during the procedure. Infections are always a risk in surgical procedures and can promote dehiscence postosteotomy, so patients require monitoring of the wound site especially around any wires, sutures, or external fixators used to secure the pubic symphysis. 

Recurrence of pubic diastasis separation is a common concern postosteotomy and occurs in up to 87% of patients who receive a combined pelvis osteotomy at <6 months of age and up to 71% in patients >6 months, necessitating a repeat closure. Lower rates are seen in anterior osteotomy cases versus posterior osteotomy.⁶ Increased rates of successful closure were seen in patients where 6–8 weeks of Buck’s traction with an external fixator was used postosteotomy.¹² Older children tend to see lower rates of recurrent dehiscence, have increased bone density that allows for better pin fixation, and are closer to the adult anatomy of the ischiopubic segment as the pelvis grows. 

Most patients will have good continence and be able to return to the same level of physical activity postoperatively. Normal gait and restoration of strength are seen except in cases of superior gluteal nerve injury. A long-term study found that exstrophy patients who did not have an osteotomy have higher relative joint force and stress levels along with increased degenerative changes in the hips on radiology.^9, 13

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