The importance of precisely understanding the pathoanatomy of acetabular dysplasia prior to surgical treatment has long been recognized. Acetabuloplasties for neuromuscular hip dysplasia have typically aimed to improve the acetabulum by increasing posterior-superior coverage, as previous three-dimensional (3-D) computed tomography (CT) studies have shown that acetabular dysplasia in neuromuscular hips is primarily in the direction of posterior-superior subluxation or dislocation. The purpose of this study was to identify differences in 3-D morphology between normal hips and dysplastic neuromuscular hips, specifically to identify areas of acetabular deficiency to guide preoperative decision-making. Patients treated for neuromuscular hip dysplasia at a single institution between 2009 and 2017 with a preoperative high-resolution pelvic CT scan (28 hips) were evaluated with custom software to measure acetabular morphology. Acetabuli were divided into equal octants; coverage angles were measured for each octant of interest. Variables were compared with ageand sex-matched normal controls (56 hips). We found a wide range of hip pathology in our study cohort. Five hips had no sectors with abnormal coverage. One hip (4%) was overcovered anteriorly. The remaining pathology was undercoverage located anteriorly [n = 7 (25%)], superiorly [n = 6 (21%)], posteriorly [n = 4 (14%)] or globally [n = 5 (18%)]. Our findings indicate that individual patients with neuromuscular acetabular dysplasia have unique deformities that do not uniformly conform to a specific area of acetabular deficiency. It is imperative to define the specific 3-D acetabular deficiency location and magnitude for accurate preoperative planning. Level of evidence: Level III.

A week before admission, a boy 3 years 3 months of age was referred to our clinic because his abdomen was large and a huge abdominal mass was palpated by his physician. On admission, the child's height was 96.5 cm, and he weighed 15.9 kg. He seemed to be in good health although his abdomen was greatly distended. His temperature and blood pressure were normal, as were the results of the rest of the physical examination, excluding the abdomen. Palpation of the abdomen showed a large mass that was soft and nontender; its margins were not discrete. No organs were palpable, and there was no edema. Hemoglobin level, leukocyte and differential cell counts, urinalysis, and roentgenogram of the chest were normal. The levels of urinary vanillylmandelic acid and homovanillic acid were normal. The serum level of creatinine was 0.45 mg/dL. Values for electrolytes, alkaline phosphatase, SGOT, and SGPT were normal.An excretory urogram (Fig 1) and abdominal aortograms (Fig 2) were done. Surgical exploration was under¬ taken. Figure 1.