The Y-Pelvic Osteotomy in Treating Bladder Exstrophy: A Surgical Technique

Abstract

Bladder exstrophy (BE) is a rare congenital anomaly caused by an embryological defect in the closure of the abdominal wall. It comprises a spectrum of defects about severity, including epispadias in the mildest form and cloacal exstrophy in the worst. Surgical correction is required to achieve urinary continence, maintain normal renal function, achieve secured abdominal wall closure, and create cosmetically and functionally satisfactory genitalia. Iliac bone osteotomy is considered essential to achieve the above goals in most patients by reducing the tension of the closed abdominal wall layers, particularly when present late in infancy. Several types of pelvic iliac bone osteotomy have been described to aid bladder and cloacal exstrophy closure. They can be grouped into posterior iliac osteotomy, anterior iliac osteotomy, oblique (also called diagonal) iliac osteotomy, and a combination of posterior and anterior iliac osteotomy. We described here the Y-pelvic osteotomy, which was developed by the Manchester Orthopaedic Group in the United Kingdom. It has the advantage of anterior and posterior osteotomies but also has less risk to the neurovascular structures, less blood loss, and ease of surgical technique. The osteotomy was named the Y-pelvic osteotomy due to the morphological shape it resembles.

Keywords: bladder reconstruction; cloacal exstrophy; epispadias and bladder exstrophy; pelvis osteotomy; persistent cloaca.

Figure 1. A newborn child with bladder exstrophy.

Notice the open abdominal wall and urinary bladder and the underdeveloped genitalia.

Figure 2. Intraoperative clinical photograph.

The abdominal muscles peeled off the iliac apophysis (dashed green arrow). The lateral cutaneous nerve of the thigh is identified and protected through the whole procedure (curved green arrow). Black arrow points to the orientation of the patient and points cranially.

Figure 3. Intraoperative clinical photograph.

The photograph shows the exposed inner aspect of the iliac wing. The iliac apophysis is split over the iliac crest (solid green arrow) into a medial half (straight dashed red arrow) and lateral half (green curved dashed arrow).

Figure 4. Intraoperative image.

The insertion of external fixation half pin under direct vision. The entry point and the exit point should be visible during the insertion. Free hip movement is used as an indicator that there is no hip joint penetration.

Figure 5. A diagram showing the planned bony cuts of the Y-pelvic osteotomy.

Top image (A) is an anteroposterior (AP) view of pelvis CT scan and bottom image (B) is inferosuperior view of pelvis CT scan. The L-shaped bony cut is marked in red and it extends just behind the anterior superior iliac spine toward the pelvis brim then turns forward away from the sacro-iliac joint. The small arm cut is performed first (denoted by red circle 1)  because this cut has to be very precise. Its location prevents inadvertent damage to the sacro-iliac joint or breaching the half pin tracts. The vertical posterior partial (dashed green line) cut extends from the angle of the “L-shaped cut” upward and parallel to the sacro-iliac joint.

Figure 6. Intraoperative clinical photograph.

Top image (A) shows the iliac bone before performing the osteotomies whereas the bottom image (B) shows the iliac bone after performing the osteotomies. The vertical incomplete cut (dashed green line) which is created using an osteotome to score the inner cortex of the iliac bone starting from the angle of the L-shaped osteotomy upward. Two incomplete, parallel and 2 mm apart cuts (like a train track) are made using an osteotome. The 2 mm cortex in-between is then peeled off leaving the outer cortex and periosteum intact. This allows the iliac bone to fold inward (dashed yellow arrow) to allow soft tissue (solid yellow line) to come closer to the midline.

Figure 7. Postoperative clinical photograph.

The photograph shows the assembled external fixator and mermaid dressing.

Figure 8. Postoperative plain radiograph.

The image shows healed osteotomies with the pins not penetrating the hip joints.