Can neonatal pelvic osteotomies permanently change pelvic shape in patients with exstrophy? Understanding late rediastasis

The true pelvic volume change with various corrective osteotomy techniques for exstrophy-epispadias complex spectrum: the value of computer-assisted virtual surgery

Pelvic osteotomies are essential to approximate widened symphysis pubis in the exstrophy-epispadias complex, yet it is unknown which osteotomy type has the greatest effect on pelvic volume. We therefore used virtual surgery to study pelvic volume change with anterior, oblique, and posterior iliac osteotomies. Preoperative CT scans of two cloacal and one classic bladder exstrophy patients were used. Simulations were free-hand or constrained to keep minimal strain in the sacrospinous SSL and sacrotuberous STL ligaments. Changes in inter-pubic distance, pelvic volume, SSL and STL strains were measured. Mean pelvic volume decreased by 10% with free hand compared to 23% with constrained simulations (P = 0.171) and decreased by 7% with posterior, 17% with diagonal and 26% with horizontal osteotomies (P = 0.193). SSL and STL were strained by 20% and 26%, respectively, with free-hand simulations. A statistically significant moderate positive correlation was found between the decrease in inter-pubic distance and reduction in pelvic volume (r = 0.6, P = 0.004). Mean pelvic volume decreased 0.05, 0.37 and 0.62% for each mm of pubic symphysis approximation with posterior, diagonal and horizontal osteotomies, respectively. Differences in effect on pelvic volume were identified between the osteotomies using virtual surgery which predicted residual diastasis in actual cloacal exstrophy surgical reconstructions. Oblique osteotomies are a compromise, avoiding difficulties with posterior osteotomies and excessive pelvic volume reduction with horizontal osteotomies. Understanding how osteotomy type affects pelvic morphology with virtual surgery may be an effective adjunct to pre-operative planning in exstrophy spectrum.

Mini-open Anterior Pelvic Osteotomy and Spica Casting for Primary Closure of the Pelvis in Infants With Classic Bladder Exstrophy

BACKGROUND

The objective of this study was to investigate the efficacy and safety of mini-open Salter-like anterior pelvic osteotomy followed by spica casting as an adjunct to urological reconstruction in infants with classic bladder exstrophy (CBE).

METHODS

Twenty-eight infants with CBE were operated upon according to the following protocol: initial bilateral mini-open Salter-like osteotomies followed by urological reconstruction and subsequent spica casting for 3 to 4 weeks. Postoperative clinical and radiologic assessments of wound complications and union were done, respectively. During subsequent follow-ups, the foot progression angle (FPA), the interpubic (IP) distance, interischial (IS) distance, and the IS/IP ratio were measured. The Pearson correlation was used to correlate between age at the time of last follow-up, the FPA, the IP and IS distances, and the IS/IP ratio.

RESULTS

The mean age at the time of operation was 5.89±0.89 months. The operative procedure took 10 to 15 minutes (mean of 12.5±1.5 min) for each side and the blood loss was negligible. Tension-free complete approximation of the symphysis was achieved in all cases. No wound complications were reported in any case. The total duration of the cast was 3.07±0.14 weeks. The mean duration of follow-up was 4.78±3.09 years. Strong positive correlation was found between the IP and IS distances ( r =0.833, P <0.0001) as well as the IS distance and age (r=0.455, P =0.015).

CONCLUSION

Mini-open anterior pelvic osteotomy and spica casting may provide a minimally invasive and effective option for closure of the pelvis in infants with CBE.

LEVEL OF EVIDENCE

Level IV-case series.

Bilateral Anterior Innominate Osteotomy for Bladder Exstrophy

Background

Bladder exstrophy is a congenital condition that affects the genitourinary and musculoskeletal systems, and less commonly affects the intestinal system, with cloacal exstrophy. This condition results from abnormal migration of the mesenchyme, between the endoderm and ectoderm, leading to anterior rupture of the cloacal membrane. Numerous osseous morphologic changes are observed in bladder exstrophy. Rotational anomalies include external rotation of the posterior part of the pelvis and iliac wings, on average 12°, and acetabular retroversion^1-3. Although various osteotomy types have been described for initial bladder exstrophy closure, the anterior approach has demonstrated positive outcomes in improving daytime continence, gait, and correction of the diastasis⁴. Thus, the anterior iliac osteotomy provides an effective method to help close the pelvic ring and decrease stress on the anterior abdominal wall during exstrophy closure. In addition, this technique promotes continence by reconfiguring, and thereby restoring, the fibrous symphyseal bar and pelvic floor musculature⁵.

Description

The steps of the procedure include (1) preoperative planning, (2) patient positioning, (3) incision, (4) identification of the lateral femoral cutaneous nerve, (5) subperiosteal dissection of the iliac wing, (6) guide pin placement and anterior osteotomy, (7) posterior hinge osteotomy (for cloacal exstrophy and for patients ≥2 years old), (8) external fixator pin placement, (9) anterior internal fixation of the pubic symphysis (for cloacal exstrophy and for patients ≥2 years old), and (10) resumption of the urologic procedure followed by wound closure and application of external fixator.

Alternatives

Numerous previous techniques for osteotomies in bladder exstrophy have been developed, starting with Shultz in 1958, who recognized the importance of bringing the pubic bones together for gait correction in exstrophy repair⁶. O'Phelan was the first, to our knowledge, to document outcomes of this bilateral posterior osteotomy technique to reduce tension from the externally rotated iliac bones and widened pubic symphysis in a 2-stage bladder exstrophy closure⁷. Other approaches have included an oblique iliac wing osteotomy and pubic ramotomy, described by Frey and Cohen in 1989⁸. However, the latter approach inadequately restores the pelvic osseous relations except in female newborns who would have a small diastasis after manual rotation of the pelvis.

Rationale

This procedure has several advantages over the prior conventional posterior approach. These include better approximation and improved mobility of the pubic rami at the time of closure, prevention of vertical migration of the hemipelvis, direct visual placement of an external fixator and adjustment postoperatively, and no requirement for turning the patient during the operation. In addition, this procedure allows for adjunctive posterior osteotomy from the anterior approach to provide adequate closure in those with cloacal exstrophy, prior failed closure, or extreme diastasis of >6 cm⁹.

Promising early results for trabecular metal acetabular components used at revision total hip arthroplasty

Aims

The aim of this study was to compare the incidence of aseptic loosening after the use of a cemented acetabular component and a Trabecular Metal (TM) acetabular component (Zimmer Inc., Warsaw, Indiana) at acetabular revision with bone impaction grafting.

Patients and Methods

A total of 42 patients were included in the study. Patients were randomised to receive an all- polyethylene cemented acetabular component (n = 19) or a TM component (n = 23). Radiostereometric analysis and conventional radiographic examinations were performed regularly up to two years post-operatively or until further revision.

Results

The proximal migration was significantly higher in the cemented group. At two years, the median proximal migration was 1.45 mm and 0.25 mm in the cemented and TM groups, respectively (p = 0.02). One cemented component was revised due to dislocation. There were no revisions in the TM group.

Conclusion

Lower proximal migration in the TM group suggests that this design might be associated with a lower risk of aseptic loosening in the long term compared with an all polyethylene cemented component. Longer follow-up is required to confirm the clinical advantages of using this component at acetabular revision. Cite this article: Bone Joint J 2017;99-B:880–6.