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To the editor:
In their paper entitled “Terminal Hemimelia of the Lower Extremity: Absent Lateral Ray and a Normal Fibula”, Baek et al.  endeavour to further define isolated metatarsal deficiency or “terminal hemimelia” by a comparison of such patients with those whose limbs exhibit “mild fibular hypoplasia”. They have accurately and appropriately portrayed those limbs as a “spectrum of dysplasia of the entire limb” involving all segments to a greater or lesser extent. They did not reference Frantz and O’Rahilly’s 1961 paper , which was the origin of the term “fibular hemimelia”.
We have previously contested  the generic designation of “lateral metatarsals” as those deficient in the fibular deficient limbs. Moreover, in their paper, examination of figure 1a, an AP radiograph of both feet of a single patient, arguably demonstrates by gross inspection absence of metatarsals two and three. In a series of five feet, which we published, it was clear that the dysplastic ray structures were not at all lateral, but midline.
Appreciation of that single observation has led to the designation of the midline foot, fibula, and proximal femur as the portions of the limb most frequently afflicted in the congenital short limb . Those anatomical regions are all sites of rapid vasculogenesis in the six-week embryo. Further, dysplasia of midline metatarsals may only be produced by degradation of a preexisting limb model. Such metatarsal deficiency can only have occurred after specification of a normal limb model.
Therefore, it is not necessary to impute theoretical models of ZPA loss or postaxial hypoplasia in the causation of this entity. We have revealed that aberrant vasculogenesis in the six-week embryo is almost uniformly associated with these birth defects . Further, it is possible to explain much of the bony pathomechanics in terms of abnormal vasculogenesis. For example, it is difficult otherwise to explain the presence of talipes equinovarus in a limb with fibular deficiency—such ankles should be in valgus. Appreciation of the embryonic arterial pathomechanics can lead to an explanation for such contradictory mechanical changes.
It seems timely now to eliminate the term “fibular hemimelia” from the orthopaedic lexicon. Such a term creates a false (in our view) impression that the limb dysplasias can be expressed in neat linear units when the precise anatomical facts are not tidy at all. With regard to the subject attempt to sub-classify an already flawed system of anatomical classification, we repeat our statement  that “it is simply premature to encompass the unknown numerically: classification begets obfuscation”.
David R. Hootnick, MD
Clinical Professor of Orthopedic Surgery
Professor of Anatomy, Cell & Developmental Biology
Clinical Associate Professor of Pediatrics