Quantifying the Effects of Hip Surgery on the Sphericity of the Femoral Head in Patients with Mucopolysaccharidosis Type I.

BACKGROUND: The introduction of stem cell transplantation has improved life expectancy and cognitive outcome in patients with mucopolysaccharidosis I, but this condition remains associated with substantial residual disease in several parts of the body. Many patients have hip dysplasia with progressive medial flattening of the femoral head. Quantitative evidence on the effect of surgery on remodeling to sphericity of flattened femoral heads is lacking. In the present study, we used statistical shape modeling to quantify the effect of hip surgery on the sphericity of the femoral head in patients with mucopolysaccharidosis I. METHODS: We performed a retrospective case control study involving a series of 23 patients with hip dysplasia due to mucopolysaccharidosis I. Surgery was not offered to the first 11 children (control group). Following a change in treatment protocol, the next 12 children underwent bilateral proximal femoral varus derotation osteotomy and Pemberton osteotomy for the treatment of acetabular dysplasia with progressive femoral head flattening (surgery group). The surgery and control groups were compared with a reference group of patients with normal hips. Statistical shape modeling was used to quantify the shape of the femoral head (i.e., flattening and/or roundness of the epiphysis). RESULTS: The mean age at the time of stem cell transplantation in the surgery and control groups was comparable (1.2 years). The mean age at the time of surgical intervention was 5.5 years, and mean duration of postoperative follow-up was 3.3 years. Statistical shape modeling showed variations within the total group in terms of medial indentation, width, height, and sphericity of the femoral heads. In contrast to the progressive femoral head flattening in the control group, the surgery group showed improvement of the sphericity of the femoral head after surgery. The overall shape characteristics of the femoral head in the surgery group were similar to those of the reference group of patients with normal hips. CONCLUSIONS: To our knowledge, this is the first study in patients with mucopolysaccharidosis I that has shown quantitative remodeling of the dysplastic, flattened femoral head to normal sphericity after increasing containment of the femoral head. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Reliability of voiding cystourethrography to detect urethral obstruction in boys.

OBJECTIVES: To evaluate the reliability of voiding cystourethrography (VCUG) to diagnose infravesical obstruction in boys. METHODS: Hard copies of the VCUG findings of 72 boys were assessed by two pediatric radiologists and two pediatric urologists. The investigators were instructed to consider six items related to infravesical obstruction: vesicoureteral reflux, bladder wall thickness, bladder diverticulum, abnormal prostatic urethra, visible urethral obstruction, and obstruction in the sphincter area. Also, a scoring system was developed using these six items. Agreement among the four investigators for evaluation of the items on VCUG and for the scoring system was assessed using the kappa statistic. All boys underwent urethrocystoscopy, and the endoscopic findings were compared with VCUG results. Odds ratios were calculated for the results of VCUG for each investigator to predict the chance of cystoscopic infravesical obstruction. RESULTS: Agreement among observers for vesicoureteral reflux and bladder diverticulum was good (kappa values for paired observers of 0.82 and 0.79). Agreement for bladder wall thickness, abnormal prostatic urethra, visible urethral obstruction, obstruction in the sphincter area, and the scoring system was poor (kappa values of 0.08, 0.35, 0.33, 0.26, and 0.33, respectively). Consequently, the results of VCUG could not predict for endoscopic infravesical obstruction accurately, although substantial differences occurred among investigators. Items on which investigators reached good agreement were negatively related to the risk of having infravesical obstruction. CONCLUSIONS: Because agreement among investigators in the assessment of most items on VCUG was poor and because for the items with good agreement, the predictive power was poor, the current clinical use of VCUG for diagnosing infravesical obstruction needs reevaluation.