title: The Erlenmeyer flask bone deformity in the skeletal dysplasias.
abstract: Erlenmeyer flask bone deformity (EFD) is a long-standing term used to describe a specific abnormality of the distal femora. The deformity consists of lack of modeling of the di-metaphysis with abnormal cortical thinning and lack of the concave di-metaphyseal curve resulting in an Erlenmeyer flask-like appearance. Utilizing a literature review and cohort study of 12 disorders we found 20 distinct disorders were associated with EFD. We interrogated the International Skeletal Dysplasia Registry (ISDR) radiographic database (1988-2007) to determine which skeletal dysplasias or syndromes were highly associated with EFD, whether it was a uniform finding in these disorders, and if forms of EFD could be differentiated. EFD was classified into three groups. The first catogory was the typical EFD shaped bone (EFD-T) resultant from absent normal di-metaphyseal modeling with relatively normal appearing radiographic trabecular bone. EFD-T was identified in: frontometaphyseal dysplasia, craniometaphyseal dysplasia, craniodiaphyseal dysplasia, diaphyseal dysplasia-Engelmann type, metaphyseal dysplasia-Pyle type, Melnick-Needles osteodysplasty, and otopalatodigital syndrome type I. The second group was the atypical type (EFD-A) due to absence of normal di-metaphyseal modeling with abnormal radiographic appearance of trabecular bone and was seen in dysosteosclerosis and osteopetrosis. The third group was EFD-marrow expansion type (EFD-ME) in which bone marrow hyperplasia or infiltration leads to abnormal modeling (e.g., Gaucher disease). Further, radiographic review determined that it was not always a consistent finding and that there was variability in both appearance and location within the skeleton. This analysis and classification aided in differentiating disorders with the finding of EFD.
authors.affiliation: Clinical Genetics, Department of Pediatrics, Riyadh Medical Complex Hospital, Riyadh, Kingdom of Saudi Arabia. maha_faden@yahoo.com
authors.forename: Maha A
authors.initials: MA
authors.lastname: Faden
authors.forename: Deborah
authors.initials: D
authors.lastname: Krakow
authors.forename: Fatih
authors.initials: F
authors.lastname: Ezgu
authors.forename: David L
authors.initials: DL
authors.lastname: Rimoin
authors.forename: Ralph S
authors.initials: RS
authors.lastname: Lachman
mesh_terms: D001847:Bone Diseases; D001848:Bone Diseases, Developmental / Q000145:classification* / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D001842:Bone and Bones / Q000000981:diagnostic imaging*; D015331:Cohort Studies; D000013:Congenital Abnormalities / Q000000981:diagnostic imaging; D005269:Femur / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D010009:Osteochondrodysplasias / Q000145:classification* / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D011859:Radiography