Bladder Exstrophy (Pelvic Manifestations)

Bladder exstrophy is the central and most common phenotype of the exstrophy-epispadias complex (EEC), a spectrum of midline lower-abdominal and pelvic malformations that runs from epispadias, the mildest, through classic bladder exstrophy to cloacal exstrophy, the most severe.

Who. The whole spectrum occurs in roughly 1 in 10,000 births; classic bladder exstrophy is around 1 in 30,000 and cloacal exstrophy around 1 in 200,000. It is more common in males, roughly 2-3 : 1.

Why the orthopaedic surgeon is there. The condition involves the bony pelvis, the pelvic floor and the abdominal wall, not only the urinary tract. The orthopaedic surgeon is a core member of the closure team.

Embryology. EEC results from abnormal development and premature rupture of the cloacal membrane, which prevents normal medial migration of mesenchyme. The earlier and larger the rupture, the more severe the defect, which is why the same underlying error produces a graded spectrum.

What is actually deformed. Three-dimensional CT studies of children with classic bladder exstrophy, compared with age- and sex-matched controls, show a consistent and reproducible pattern:

• Pubic diastasis. The pubic bones are widely separated, on average around 4.2 cm against around 0.6 cm in controls, so the anterior pelvic ring is essentially open.
• External rotation of the posterior pelvis. The iliac wings are externally rotated around 11-12 degrees more than normal, and the sacroiliac joints are more externally oriented, by around 10 degrees.
• Inferior rotation of the pelvis. The whole pelvis is rotated in the superoinferior plane, by around 15 degrees, a feature only appreciated on 3D imaging.
• Widened inter-triradiate distance. The triradiate cartilages sit further apart (around 6 cm against around 4 cm), reflecting the externally rotated, splayed-open ring.
• Acetabular retroversion. The acetabula face more posteriorly than normal.

Putting it together. Imagine the two hemipelves hinged on the central sacrum and swung outward. The swing opens the front of the ring, separates the pubic bones and tilts the sockets, and it stretches and displaces the pelvic floor and the would-be symphyseal bar. The corrective logic of surgery is to reverse that swing, rotating the hemipelves back together so that the pubis can meet.

Why the soft tissues matter too. Approximating the pubis is not only cosmetic. It reconstitutes the pelvic floor sling and the fibrous symphyseal bar, which support continence mechanisms and abdominal wall closure, and so links the bony correction directly to the urological outcome.

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The exstrophy-epispadias complex is graded by severity:

• Epispadias, the mildest: an open dorsal urethra with mild or absent diastasis. Often no osteotomy is required.
• Classic bladder exstrophy: an open bladder plate, wide pubic diastasis and externally rotated ilia. This is the typical osteotomy candidate.
• Cloacal exstrophy, the most severe: exstrophy plus omphalocele, imperforate anus and frequently spinal anomalies. It has the greatest diastasis and the most demanding reconstruction.

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At birth. There is an obvious midline lower-abdominal wall defect, with an exposed, everted bladder plate in classic exstrophy or an open urethral plate in epispadias, and a wide gap between the pubic bones is palpable. Externally rotated lower limbs may be noted, but the hips are usually clinically stable. Cloacal exstrophy brings its omphalocele and imperforate anus, and may bring lower-limb or spinal anomalies.

The orthopaedic examination. It has three tasks:

• Confirm the diastasis and document its width
• Examine the hips for range and stability; frank dislocation is uncommon, but assess
• Examine the spine and lower limbs, particularly in cloacal exstrophy, where neural tube and limb anomalies are more frequent

Prenatal clues. Repeated non-visualisation of a normally filled fetal bladder on ultrasound, with a lower abdominal wall bulge, should prompt suspicion. Recognising it allows planned delivery at a specialist centre.

Plain radiographs. An AP pelvis or KUB film is first-line and sufficient to recognise the deformity, showing the pubic diastasis and the externally flared iliac wings. It is also the film on which the inter-symphyseal (pubic) distance is measured before and after surgery and approximation is monitored over time.

Three-dimensional CT. 3D-CT is the reference standard for understanding and planning. It quantifies the iliac wing angle, sacroiliac joint angle, pubic diastasis, inter-triradiate distance and acetabular version, and it reveals the inferior pelvic rotation that plain films do not show. It is particularly valuable for redo closures, cloacal exstrophy and osteotomy planning.

The whole child. The shared assessment goes beyond the pelvis:

• Renal and urinary tract imaging (ultrasound, MCUG, urogram), in the urological remit
• Spinal imaging in cloacal exstrophy, to exclude dysraphism and tethered cord
• Echocardiography and a general anomaly screen before major neonatal surgery

The principle. The orthopaedic goal is to reverse the external rotation of the hemipelves so that the pubic bones can be brought together. That takes tension off the bladder and abdominal wall closure and helps to reconstruct the pelvic floor, and the bony correction in turn supports the urological aims of a secure closure and eventual continence.

When to osteotomise. Osteotomy is indicated for:

• Classic bladder exstrophy with significant diastasis
• Delayed or failed primary closure
• Cloacal exstrophy
• Most closures beyond the immediate newborn period

The newborn exception. In the first 48-72 hours the pelvis is malleable, and some surgeons close without osteotomy. Osteotomy becomes increasingly important as the child gets older or when the diastasis is wide.

Which osteotomy. Four are used in closure:

• Bilateral anterior (innominate) osteotomy is the modern workhorse. The anterior approach allows direct external fixator placement and good pubic approximation, and supports continence and gait; a posterior hinge cut can be added for severe cases.
• Posterior iliac osteotomy was the historical original approach and has fallen out of favour as the sole technique.
• Combined anterior and posterior osteotomy is preferred for cloacal exstrophy, redo closures or very wide diastasis (over 6 cm).
• Oblique pelvic (iliac) osteotomy is an alternative described in neonates and for difficult or secondary closures.

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Immobilisation is part of the operation. It is as important as the osteotomy itself: loss of fixation is a leading cause of closure failure, and immobilisation typically lasts several weeks, until the closure is secure. The methods are not equal:

• External fixation with lower-limb traction (modified Buck's traction) has given the best reported success rates
• Spica casting and simple wrapping are less effective and carry higher complication rates
• Custom braces and selected two-pin external-fixation protocols are newer, and aim to ease nursing and wound care while maintaining stability

Staging and the team. Combined paediatric urology and paediatric orthopaedics is the standard of care. A single-stage closure (complete primary repair) closes the bladder, posterior urethra and abdominal wall in one operation; a staged closure closes the bladder and abdominal wall first and leaves the bladder neck and continence procedures for later. The choice is individualised, but in large cohorts, especially in cloacal exstrophy, and in difficult cases, staged combined-osteotomy approaches have been associated with higher closure success when done by an experienced multidisciplinary team.

Why the first closure matters most. Successful initial closure is the single most important determinant of later bladder capacity and continence. It is worth doing once, well.

Failed closure. Failed or dehisced closure is the most consequential complication, strongly linked to inadequate osteotomy or immobilisation, and it may need revision osteotomy and closure. The continence and urological sequelae lie downstream of the closure outcome.

Hazards of the surgery and immobilisation. The operation and the weeks of immobilisation carry their own risks:

• External fixator pin-site infection or loosening, usually managed without long-term harm
• Pressure ulcers and nerve compression (for example the femoral nerve) from traction and immobilisation, largely avoidable with good technique
• Lateral femoral cutaneous nerve injury during anterior approaches; protect it during exposure

The diastasis recurs partially. Even with good approximation at surgery, the anterior pelvic segment does not develop normally and often cannot stay fully approximated. Some recurrence of the diastasis over time is expected, and it is usually well tolerated.

Gait is usually good. In large orthopaedic series the great majority report no pain or functional disability. A minority have a waddling gait or external rotation of the hips, and in most it normalises.

The hips generally do well. Despite acetabular retroversion, frank hip dysplasia or dislocation is uncommon, and most patients are community ambulators.

The adult who never had an osteotomy. In Nehme's series of 31 adults with bladder exstrophy who never had a pelvic osteotomy (62 hips, mean age 30), 58 percent of hips had a retroverted acetabulum and the rest were neutral or anteverted. Yet 60 of the 62 hips had no arthritis, and the mean lateral centre-edge angle was a normal 32 degrees (DOI). The retroversion is real and common, and it alters hip biomechanics, but it is usually well tolerated and early osteoarthritis is uncommon.

Two different hip concerns. Dysplasia and dislocation are uncommon: despite the deformity, frank instability is rare, and routine DDH-style treatment is seldom needed. Retroversion is the commoner finding and a theoretical pincer-FAI substrate, usually silent and an occasional source of hip symptoms or an external-rotation gait. For the minority who report either, it is a better explanation than dysplasia.

Recognising retroversion. On a well-centred AP pelvis it shows as the crossover, posterior-wall and ischial-spine signs, provided the film is not tilted or rotated, because a malpositioned pelvis manufactures a false crossover sign. The exstrophy pelvis is itself globally rotated, which makes AP crossover-type signs unreliable, so apparent orientation on the AP film must be correlated with acetabular version on axial CT, which is essential here.

What to do about it. Most hips stay arthritis-free, which argues for awareness and surveillance rather than routine intervention. The osteotomy that corrects the diastasis also partially re-orients the externally rotated, retroverted sockets.

The arthritic adult hip. Adult hip pain may reflect dysplasia, impingement or arthritis rather than the pubic gap itself. Coronal CT, for bone stock and centre-of-rotation planning, complements the axial assessment of version.

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Arthroplasty in the rotated pelvis. Standard landmarks and cup targets cannot be assumed in an externally rotated exstrophy pelvis, so cross-sectional imaging maps the wide anterior ring and abnormal acetabular orientation before arthroplasty. These are bespoke adult reconstructions that require CT planning rather than routine primary-THA assumptions.

Planning and implants. Virtual reconstruction identifies the native acetabular bed and the cup size, centre and version despite severe pelvic rotation, and patient-specific planning reduces the risk of malposition, impingement and instability. Anteverted liners and stable fixation compensate for severe acetabular retroversion and deficient bone.

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Spinal dysraphism is the rule. Far more often than in classic exstrophy, the child with cloacal exstrophy has an open or occult dysraphism (lipomyelomeningocele, myelomeningocele, a split-cord or diastematomyelia malformation, sacral agenesis or other vertebral anomalies) and a tethered cord. The dysraphism is therefore assumed until imaging excludes it, rather than looked for only if the legs seem weak.

The consequences are neurological as well as bony. They are what most limit walking, more than the pelvic ring:

• A myelodysplasia-pattern lower-limb neurological deficit
• Neuropathic bladder and bowel beyond the exstrophy itself
• Lower-limb anomalies: limb hypoplasia, foot deformities, hip dysplasia
• Later neuromuscular scoliosis

Workup. Every child with cloacal exstrophy needs spinal MRI and neurosurgical assessment for a tethered cord, planned alongside the pelvic closure. Release may be needed to prevent progressive neurological loss.

Prognosis follows the cord. In Jasiewicz's report of a split-notochord / cloacal-exstrophy child with a double sacrum and a split cord, independent walking, even with a prosthesis for a hypoplastic limb, can be feasible, and "walking ability and quality of life depend on the neurologic deficits" (DOI).

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Global epidemiology

• The exstrophy-epispadias complex affects roughly 1 in 10,000 births worldwide, with classic bladder exstrophy around 1 in 30,000 and cloacal exstrophy around 1 in 200,000; males predominate.
• It is rare enough that outcomes are best in high-volume specialist centres, and much of the published evidence comes from a small number of such units.

Side-by-side practice variation

Registry and evidence notes

• There is no dedicated exstrophy implant registry; the evidence base is institutional case series and comparative reviews, so individual high-volume-centre series carry disproportionate weight.
• Consistent messages across series: osteotomy improves closure success, secure immobilisation is essential, and long-term gait/hip function is generally good.

High- vs limited-resource practice

• In well-resourced settings, 3D-CT planning, anterior osteotomy with external fixation and multidisciplinary uro-orthopaedic teams are standard, and most children are managed in specialist referral units.
• In limited-resource settings, plain radiography guides assessment, osteotomy technique may be adapted to available fixation, and the priorities are achieving and protecting a secure closure and avoiding immobilisation complications. Centralising these rare cases to experienced teams improves outcomes everywhere.

1. Whether the newborn needs an osteotomy at all

• The strongest disagreement in the field. Some units close within the first 48-72 hours without osteotomy, relying on the residual laxity of the neonatal symphysis and sacroiliac joints; others osteotomise every child on the grounds that the closure is only worth doing once and tension is what makes it fail.
• Why it stays unsettled: the comparison is confounded at its root. The babies closed without osteotomy are, by selection, the ones who present early, are otherwise well, and have a narrower diastasis - so a series showing that osteotomy-free newborn closure works may be describing a favourable subgroup rather than an equivalent technique. No randomised comparison exists and, given the rarity, none is likely.

2. Which osteotomy

• Bilateral anterior innominate osteotomy is the modern workhorse, but posterior iliac, combined anterior-posterior and oblique/diagonal iliac osteotomies all have advocates, and the published series are small, single-centre and use different closure protocols alongside them.
• Because osteotomy and immobilisation are always changed together, it is rarely possible to say which of the two produced a better closure rate - the technique and the fixation are confounded in almost every series.

3. How much recurrent diastasis matters

• Partial recurrence of the diastasis is expected, because the anterior segment does not develop normally whatever is done to it. What is genuinely unknown is whether the degree of recurrence predicts anything a patient will feel - continence, gait or later hip symptoms - so a widening measurement on a surveillance film has no agreed threshold for action.

4. Whether to do anything about acetabular retroversion

• Retroversion is present in roughly half of adult exstrophy hips and is a recognised pincer-FAI substrate, yet arthritis in that same cohort was uncommon. Whether the minority who develop hip pain in adult life would benefit from FAI-style treatment, and whether any early intervention prevents it, is unanswered - so current practice is recognition and surveillance, not prophylaxis.

5. Whether closure success or bladder biology drives continence

• It is well established that a secure first closure is associated with better later bladder capacity and continence. Whether that is because failed closures mechanically injure the bladder, or because the bladders that fail to close were the more abnormal ones to begin with, is not settled - and it changes how much of the outcome we should attribute to surgical technique.