Congenital fibular dystrophisms conform to embryonic arterial dysgenesis

Abstract

The congenital short limb (CSL) with fibular deficiency has traditionally been graded by plain radiography. The most popular orthopedic classification sorts the fibular dysmorphologies into three radiographic groupings: IA (thinned), IB (proximally truncated), or II (absent). In contrast, the soft tissues have been relatively neglected. Since bone formation of the fibula progresses from the anlage, a scaffolding cartilage mold intermediate, cartilage transformation to bone is dependent upon timely embryonic arterial invasion. Absences of the requisite arteries predicate specific skeletal dysmorphologies. The usual arterial supply of the fibula is comprised primarily of the anterior tibialis artery (ATA), which uniquely supplies the proximal portion of the fibula, and also joins the peroneal artery (PA) in supplying the mid to distal fibular shaft. Combinations of the two nutrient arteries allow four potential variations of fibular vascular supply, among which the ATA and PA conjoin to supply the normal fibula and variably supply the three dysmorphic fibular models. The IA and IB deformities conform, respectively, to the absences of the PA and the ATA. Combined ATA and PA absences present in the radiographically "absent" fibula. Thus, each of the four fibular (dys)morphologies conforms to a specific embryonic pattern of arterial development. The term "dystrophism" most accurately characterizes such malformed long bones.

The vascular origins of antero‐medial tibial bowing in congenital fibular deficiency

“…That syndromic triad of long bone deficiencies are all sites of vascular transition (Figure 7; Senior, 1985) during the sixth to seventh embryonic weeks (Senior, 1919a; Senior, 1919b). The arterial supply of the bowed tibiae, in association with the demonstrated arterial alterations of the fibulae, is also consistently anomalous (Hootnick, 2020a; Hootnick et al, 1980) (Figure 3c,d).…”

“…Although O'Rahilly conceded that it is undeniable that anomalous limbs should be considered in their totality with detailed studies of their soft tissues (O'Rahilly, 1951), classifications have been based on the more easily and less expensively obtained plain radiographs of affected limbs. (Hootnick, 2020a, 2020b).…”

“…Congenital fibular deficiency has also been aggregated with associated proximal femoral and midline metatarsal long bone deficiencies into a clinical syndrome (Hootnick, 2020a; Hootnick & Vargesson, 2018). That syndromic triad of long bone deficiencies are all sites of vascular transition (Figure 7; Senior, 1985) during the sixth to seventh embryonic weeks (Senior, 1919a; Senior, 1919b).…”

“…In contrast, vascular dysgenesis, especially via failure of embryonic arterial progression, has been established as a factor in limb teratogenesis (Hootnick & Vargesson, 2018; Vargesson & Hootnick, 2017). For example, among the spectrum of congenital fibular dysmorphologies (Achterman & Kalamchi, 1979), the most frequent long bone congenital deficiencies have been portrayed as evincing intimate relationships with maldevelopment of their specific anterior tibial artery (ATA) and peroneal artery (PA) nutrient vessels (Hootnick, 2020a). Since both fibular nutrient arteries are embryologically composite vessels (Senior, 1919a; Senior, 1919b), failure of the ongoing vascular progression exposes the developing fibular anlagen to recurrent incidences of the risk of teratogenesis (Figure 6 IA , IB , II ) (Hootnick & Vargesson, 2018; Levinsohn, Hootnick, & Packard Jr., 1991; Vargesson & Hootnick, 2017).…”

“…Consideration of a vascular origin of tibial bowing in CFD originated in the earlier arteriography studies of CSL limbs, which have uniformly demonstrated absences of the PTA, ATA and PA, as a result of failed embryonic vascular progression (Hootnick et al, 1980). Each of the variety of fibular skeletal dystrophisms (Figure 6: IA , IB , II ) have been characterized by a specific pattern of failed ingrowth of the ATA and/or PA nutrient arteries (Hootnick, 2020a). Other anomalous arteries supply the tibia (Hootnick et al, 1980).…”