GYN/OB-1. Isolated femoral dysplasia is a sonographic manifestation of congenital rickets.

Congenital rickets is a rare disease, especially in developed countries with adequate sunlight. It may be due to an inherited genetic disorder, metabolic bone disease, or secondary to maternal renal disease or malnutrition. The diagnosis is generally established based upon characteristic physical findings, radiographic signs, and laboratory testing, typically after 3 months of age. The patient was a 22-year old African American female, Gravida 2, Para 0102 referred to the perinatal service at 16 weeks of gestational age. She had a significant medical history of sickle cell anemia, with previous sickle crises and blood transfusions in the past. She had no personal history of renal disease or family history of other inherited genetic or chromosomal disorders. Her past obstetric history was significant for a twin pregnancy with PPROM and preeclampsia, delivered by primary cesarean section at 31 weeks of gestational age. Conception of the case pregnancy occurred approximately 3 months after delivery of her twins. Ultrasound performed at 21 weeks of gestational age revealed femoral biometry that measured below the 5th percentile for gestational age. "Bowing" of the femurs was also noted. The anatomic and skeletal surveys were otherwise normal. The femoral growth pattern continued to lag behind predicted values during serial sonographic evaluations. The femurs continued to display an abnormal curvature. A repeat cesarean section was performed at 36 weeks of gestational age, after documenting fetal pulmonary maturity via amniocentesis. There was evidence of isolated "femoral hypoplasia" based upon initial neonatology team evaluation. Biochemical and radiological testing ultimately confirmed congenital rickets, consistent with maternal vitamin D deficiency. Fetal skeletal dysplasias are a heterogeneous group of malformations with over 200 classified disorders of skeletal growth. Our case represents the first reported case of sonographically detected femoral dysplasia as a marker of maternal malnutrition and congenital rickets.

Wayne H. Friedman, MD, T. Brian Leigh, MD, and Anthony B. Royek, MD.