Background: A radiologic diagnosis of hypochondroplasia is hampered by the absence of age-dependent radiologic criteria, particularly in the neonatal period.
Objective: To establish radiologic criteria and scoring system for identifying neonates with fibroblast growth factor receptor 3 (FGFR3)-associated hypochondroplasia.
Materials and methods: This retrospective study included 7 hypochondroplastic neonates and 30 controls. All subjects underwent radiologic examination within 28 days after birth. We evaluated parameters reflecting the presence of (1) short ilia, (2) squared ilia, (3) short greater sciatic notch, (4) horizontal acetabula, (5) short femora, (6) broad femora, (7) metaphyseal flaring, (8) lumbosacral interpedicular distance narrowing and (9) ovoid radiolucency of the proximal femora.
Results: Only parameters 1, 3, 4, 5 and 6 were statistically different between the two groups. Parameters 3, 5 and 6 did not overlap between the groups, while parameters 1 and 4 did. Based on these results, we propose a scoring system for hypochondroplasia. Two major criteria (parameters 3 and 6) were assigned scores of 2, whereas 4 minor criteria (parameters 1, 4, 5 and 9) were assigned scores of 1. All neonates with hypochondroplasia in our material scored ≥6.
Conclusion: Our set of diagnostic radiologic criteria might be useful for early identification of hypochondroplastic neonates.
Keywords: Achondroplasia; FGFR3; Hypochondroplasia; Neonate; Radiography; Radiologic diagnosis; Scoring system.