Vertebral scalloping in neurofibromatosis type 1: a quantitative approach.

OBJECTIVE: To investigate quantitative differences in vertebral scalloping between children who have scoliosis with and without neurofibromatosis type 1 (NF1). DESIGN: A retrospective study. SETTING: A university-affiliated children's hospital. PATIENTS: Twenty-seven children with scoliosis, 13 of whom had NF1 and 14 of whom did not. METHOD: Existing radiographs of the lumbar vertebrae were used to measure and compare the degree of vertebral scalloping. MAIN OUTCOME MEASURES: The distribution of posterior scalloping ratios in the 2 groups and the most extreme ratio in each subject in each group were compared. RESULTS: Scalloping ratios from the children with NF1 were not normally distributed: 31% had ratios greater than 1.20. Scalloping ratios from the non-NF1 children were normally distributed, with a mean ratio (and standard deviation) of 1.13 (0.03). The distribution between the 2 groups was significantly different (p < 0.05). CONCLUSIONS: In children who have scoliosis but no NF1 there was a range of mild scalloping whereas those with NF1 has severe scalloping. Further studies are needed to determine the possible role of vertebral scalloping in scoliosis severity and progression in children who have NF1.