Nail-patella syndrome (synonyms: Fong’s disease, Trauner-Rieger syndrome) is a rare autosomal dominant condition. Clinically the key feature is absent/hypoplastic nails from birth.
Diagnostic radiographic findings include the following:
absent/hypoplastic patellae (with a tendency to recurrent dislocation)
hypoplasia of the radial head or capitellum (leading to subluxation/dislocation)
bilateral posterior iliac horns (due to exostoses arising from the posterior aspect of the iliac bones are present in as many as 80% of patients; this finding is considered pathognomonic for the syndrome)