Acetabular morphology in bladder exstrophy complex

Radiographic calibration for pubic diastasis assessment in bladder exstrophy-epispadias complex: a phantom study

BACKGROUND

The assessment of pubic diastasis is important for the surgical planning of patients with bladder exstrophy-epispadias complex. Understanding how the diastasis changes during surgical follow-up may help predict patient morbidity. Radiography can follow diastasis but may be affected by patient and technical imaging factors including body size, imaging protocol, and equipment. Using imaging calibration and anatomic ratios may mitigate differences due to these aspects.

OBJECTIVE

Use imaging phantoms to assess the effect of radiographic calibration on measurements of pubic diastasis and an internal anatomic ratio as a child grows.

MATERIALS AND METHODS

Radiographic images were obtained of three different sizes of computed tomography phantoms (older child, child, and infant) using three imaging techniques that include the osseous pelvis in children. All phantoms were imaged with abdomen and pelvis techniques. The infant phantom was additionally imaged using a thoracoabdominal technique. These exposures were all repeated with systems from three manufacturers. Linear measurements were made between radiographic markers placed to simulate pubic diastasis and sacral width. A ratio was also created between these distances. Measurements with and without image calibration were made by two pediatric radiologists using rulers placed at the time of image acquisition.

RESULTS

There was excellent interrater agreement for measurements, ICC >0.99. Anterior distances were more affected by magnification than posterior ones with a significant difference between uncalibrated versus calibrated anterior distances (p=0.04) and not for posterior ones (p=0.65). There was no difference between radiographic equipment manufacturers without or with calibration (p values 0.66 to 0.99). There was a significant difference in simulated pubic distance between thoracoabdominal and abdomen (p=0.04) as well as pelvic (p=0.04) techniques which resolved with calibration, each p=0.6. The ratio between the simulated pubic diastasis and sacral width differed by phantom size (all p<0.01) and imaging technique (p values 0.01 to 0.03) with or without calibration. However, the numerical differences may not be clinically significant.

CONCLUSION

Image calibration results in more uniform measurements that are more accurate than uncalibrated ones across patient size, imaging techniques, and equipment. Image calibration is necessary for accurate measurement of inter-pubic distances on all projection imaging. Small differences in the pelvic ratio likely are not clinically significant, but until there is a better understanding, image calibration may be prudent.

Surgical Treatment of Late Developmental Dysplasia of the Hip in Bladder Exstrophy: A Case Report

CASE

We present a case of an 8-year-old boy with classical bladder exstrophy and a neglected right hip dislocation, exemplifying the risk of missed developmental dysplasia of the hip (DDH) in patients with exstrophy requiring careful orthopaedic oversight.

CONCLUSIONS

When treating patients with bladder exstrophy, physicians and surgeons should be vigilant not to miss associated DDH. If this condition requires surgical treatment, preoperative planning with computed tomography scans is vital to uncovering the complexities arising from abnormal pelvic and acetabular anatomy and ensuring successful treatment outcomes.

Hip Prognosis in Patients With Congenital Diastasis of the Pubic Symphysis

BACKGROUND

Congenital diastasis of the pubic symphysis (CDPS) is a rare musculoskeletal malformation in the exstrophy-epispadias complex that is potentially associated with the development of hip dysplasia. The purpose of this study was to investigate the incidence and prognostic factors of hip dysplasia in patients with CDPS.

METHODS

Fifty-four hips in 27 patients with CDPS initially evaluated between 1983 and 2016 were retrospectively reviewed. The mean age at the first visit was 2.3 (0 to 8) years. The mean follow-up duration was 10.5 (1 to 36) years. Patient characteristics at the first visit, the clinical course at the most recent follow-up, and radiologic parameters on pubic malformation and hip dysplasia during at least 2 time points (first visit or age 1, and either the most recent visit or before hip surgery) were evaluated. Prognostic factors associated with the development of hip dysplasia were analyzed using univariate/multivariate analysis. The Kaplan-Meier survival curves were generated and compared based on these factors.

RESULTS

Nine of 27 patients (33%) and 13 of 54 hip joints (24%) with CDPS developed hip dysplasia. Paraplegia (odds ratio, 10.0; 95% confidence interval, 1.7-76.6) and center-edge angle of <5 degrees at the first visit or age 1 (P<0.001) were independent predictors of the development of hip dysplasia. Patients with CDPS and either paraplegia or center-edge angle <5 degrees at the first visit or age 1 were significantly more likely to develop hip dysplasia than other patients (hazard ratio, 29.3; 95% confidence interval, 3.4-250).

CONCLUSIONS

Approximately one third of patients with CDPS develop hip dysplasia. Paraplegia and center-edge angle of <5 degrees at the first visit are independent risk factors.

LEVEL OF EVIDENCE

Level III.

Osteotomy in the newborn classic bladder exstrophy patient: A comparative study

INTRODUCTION

Pelvic osteotomy is indicated in classic bladder exstrophy (CBE) patients with a wide pubic diastasis or non-malleable pelvis. While the safety of pelvic osteotomy in delayed and failed closures is established, there remains less clarity on their safety in newborns. The authors herein sought to present their experience with CBE patients who underwent pelvic osteotomy for assistance with bladder closure during both the newborn and delayed time periods.

OBJECTIVE

The authors hypothesize that pelvic osteotomy during exstrophy closure may be performed safely in newborns with few perioperative or post-operative negative sequelae.

STUDY DESIGN

A prospectively maintained IRB-approved database was reviewed for CBE patients who underwent osteotomy during primary closure. Patient demographics, performing institution (authors' or outside), closure outcome, diastasis width, and post-operative complications were noted. Patient subgroups included newborn and delayed (>28 days of life) closures. Failure was defined as bladder dehiscence, prolapse, outlet obstruction, or vesicocutaneous fistula requiring reoperation. Orthopedic complications included nerve palsies, superficial pin-site infection, and bladder neck erosion by orthopedic hardware. Analyses were performed using a Chi-square test.

RESULTS

286 patients were included: 186 newborn and 100 delayed closures. The authors' institution performed 109 cases (44 newborn and 65 delayed). Within the overall newborn closure cohort, no significant differences were found in outcomes among the osteotomy types with success rates of 80%, 60.8%, and 71.4% in the combined, posterior iliac, and anterior innominate groups, respectively (p = 0.24). In the delayed group, success rates were significantly different with rates of 100%, 72.4%, and 93.8% in the combined, posterior iliac, and anterior innominate groups, respectively (p < 0.001). Febrile urinary tract infection (UTI) was the most common complication at 8% (23/286). Only 1.7% (5/286) of patients had orthopedic complications with 3 patients in the newborn cohort, 2 patients in the delayed cohort, and only one patient requiring reoperation.

DISCUSSION

Orthopedic complications are rare in CBE patients who undergo osteotomies regardless of the closure period. No clinically significant difference in orthopedic complication rate was found between newborn and delayed closure periods.

CONCLUSIONS

While current trends have moved toward delayed primary closures, there remains a role for osteotomy during exstrophy closure in select newborn patients and can be performed safely with few complications.

Volumetric and acetabular changes in the bony pelvis associated with primary closure of classic bladder exstrophy

INTRODUCTION

Repair of classic bladder exstrophy (CBE) is known to alter dimensions of the bony pelvic ring. Pelvic volume and acetabular configuration are additional metrics which merit analysis in the reconstruction process. Advances in magnetic resonance imaging (MRI) allow for precise elucidation of such anatomy in pediatric patients, providing enhanced knowledge of how primary reconstruction may impact factors in pelvic health.

METHODS

An IRB-approved exstrophy-epispadias database of 1337 patients was reviewed for patients with CBE who had pelvic MRI performed before and after repair. Pelvic MRIs were analyzed by a pediatric radiologist, and three-dimensional volumetric renderings of the true pelvis were calculated. Pre- and post-closure imaging were compared, in addition to imaging from age-matched controls without pelvic pathology. Cartilaginous acetabular index and version angles were also calculated and compared between groups.

RESULTS

Eighteen patients with post-closure imaging, 14 of whom also had pre-closure imaging, and 23 control patients (ages 0-365 days) were included. The median ages at pre- and post-closure scan were 2 and 178 days, respectively. Osteotomy was performed in 6 (33%) of the closures. The median segmented pelvic volumes were 89 cm³ in the pre-closure group, 105 cm³ in the post-closure group, and 72 cm³ in the control group. At a given age, patients with CBE pre-closure had the largest pelvic volume, and those without bladder exstrophy demonstrated the smallest pelvic volumes (Summary Figure). CBE patients' pelvic volumes were overall lower following repair, relative to age (p = 0.007). Cartilaginous acetabular version angle increased following closure, with acetabular orientation converting from retroversion to anteversion in all cases. However, only acetabular version angles were significantly different between groups.

DISCUSSION

This study found that pelvic volume significantly decreased relative to age following primary repair of CBE, but that it did not correct to control levels. Similarly, acetabular retroversion that is naturally seen in exstrophy patients was converted to anteversion post-closure but did not become completely normal. Knowledge of these persistent anatomical anomalies may be useful in treatment of future concerns related to exstrophy, such as continence achievement, pelvic organ prolapse, and potential gait disturbances. Lack of significant differences between study groups regarding acetabular index angles can give assurance to providers that hip dysplasia is neither a natural concern nor iatrogenically inflicted through reconstruction.

CONCLUSIONS

The primary closure of exstrophy results in pelvic volumes and anteverted acetabula that more closely resemble those without bladder exstrophy, compared to pre-closure findings.

New Insights on the Basic Science of Bladder Exstrophy-epispadias Complex

The exstrophy-epispadias complex is a rare congenital anomaly presenting as a wide spectrum of disorders. The complex nature of this malformation leads to continuous investigations of the basic science concepts behind it. Elucidating these concepts allows one to fully understand the mechanisms behind the disease in order to improve diagnosis, management, and treatment ultimately leading to improvement in patient quality of life. Multiple technological advancements within the last 10 years have been made allowing for new studies to be conducted. Herein, the authors conduct a literature review of studies from 2009 to 2019, considering novel theories regarding the genetics, embryology, bladder, bony pelvis, prostate, and genitalia of patients with bladder exstrophy-epispadias complex.

Bony abnormalities in classic bladder exstrophy: the urologist's perspective

INTRODUCTION

As the primary practitioner managing patients with classic bladder exstrophy (CBE), it is incumbent upon the pediatric urologist to understand the associated orthopedic anomalies and their management.

METHODS

A Pubmed search was performed with the keyword exstrophy. Resulting literature pertaining to orthopedics and published references were reviewed.

RESULTS

Anatomic changes to the bony pelvis include outward rotation, acetabular retroversion with compensatory femoral anteversion, anterior pubic shortening, and pubic diastasis. Imaging options have improved, which impacts surgical planning. Surgical approach, including type of osteotomy and method of pubic approximation, is evolving. Most centers employ immobilization after surgery, with external fixation, Bryant's traction, Buck's traction, and spica casting being the most common methods. Orthopedic complications range from minor pin-site infections to neurologic and vascular compromise. Most experts agree osteotomy aids bladder closure beyond 72 h of life, but effect on continence remains controversial. Although no significant orthopedic benefit has been expounded, it may be too early to appreciate improvement in frequency or severity of osteoarthritis or hip dysplasia.

CONCLUSION

While orthopedic surgeons remain vital to managing exstrophy patients, knowledge of the anatomy, imaging, surgical approaches, and immobilization enable effective communication with parents and other physicians, improving care for these complicated patients.

Effect of pelvic osteotomy in the skeletally immature on acetabular coverage

BACKGROUND

Although pelvic osteotomy in children has been effective in re-establishing containment of the hip joint, its impact on hip joint development with respect to acetabular coverage is ill defined.

PURPOSE

The purpose of this study is to determine the prevalence of acetabular overcoverage in patients who had pelvic osteotomy during childhood and its impact on patient function.

PATIENTS AND METHODS

Between 1980 and 2008, all patients who had a pelvic osteotomy done at our institution for non-neuropathic hip dysplasia (DDH) or secondary to Legg-Calvé-Perthes disease (LCP) prior to skeletal maturity were reviewed. A clinical assessment and the WOMAC, UCLA Activity Score, Marx activity score, and SF-36 quality-of-life questionnaires were completed. A standardized AP pelvic X-ray was performed to determine the acetabular coverage, signs of retroversion, and degenerative changes.

RESULTS

Twenty-eight patients (32 hips) were identified, of which 14 (9 DDH, 5 LCP) agreed to participate. Impingement sign was positive in eight patients (six DDH, two LCP). Crossover and ischial spine signs were each present in ten hips. Tonnis grades were: 0 in 1 hip, 1 in 10 hips, 2 in 2 hips, and 3 in 1 hip. The mean Tonnis angle was 11.6 ± 8.6°. The mean CE angle was 24.0 ± 15.9° with six hips having a CE angle <20° and one hip with a CE angle >40°. There was no correlation between crossover sign or ischial sign and Tonnis grade (p = 0.739), hip pain (p = 0.520), or impingement sign (p = 1.00).

CONCLUSIONS

Acetabular overcoverage is common in patients who underwent pelvic osteotomy during childhood. No correlation was identified between retroversion and hip pain in our patient cohort.

Reliability of radiographic signs for acetabular retroversion

Acetabular retroversion may contribute to femoroacetabular impingement and lead to osteoarthritis of the hip. Retroversion has been measured on computed tomography scans. In recent years, assessment of acetabular version on anteroposterior pelvic views has gained increasing attention. We therefore aimed to determine the reliability of radiographic signs of acetabular retroversion and its association with the rater's experience. Five orthopedic surgeons (o1 to o5) rated the crossover sign, ischial spine sign and posterior wall sign on X-rays of 40 hip joints. Also, we determined the rater's experience in recognizing acetabular retroversion with a questionnaire and correlated intraobserver reliability to the calculated experience score. The intraobserver results were 0.325 (o1), 0.848 (o2), 0.684 (o3), 0.701 (o4), and 1.000 (o5) for the crossover sign, 0.750 (o1), 0.890 (o2), 0.593 (o3), 0.483 (o4), and 0.946 (o5) for the posterior wall sign; and 0.578 (o1), 0.680 (o2), 0.595 (o3), 0.375 (o4), and 0.800 (o5) for the ischial spine sign. Interobserver reliability was 0.514 for the crossover, 0.633 for the posterior, and 0.543 for the ischial spine sign wall. The experience sum score correlated to the kappa results for the crossover (r = 0.527), posterior wall (r = 0.738), and ischial spine sign (r = 0.949). Assessing acetabular version on plain radiographs is subject to intra- and interindividual error and related to the observer's individual experience.