David S. Packard

Pulsed color-flow Doppler analysis of arterial deficiency in idiopathic clubfoot.

This prospective study used pulsed color-flow Doppler sonography to determine differences in the presence and direction of flow through the dorsalis pedis, posterior tibial, and peroneal arteries in a group of children with clubfoot and a comparison group of controls. There was a statistically significant difference in the prevalence of deficient (absent or retrograde flow) dorsalis pedis arteries in children with clubfoot (45%) compared with controls (8%). This indicates that there is an association between some clubfeet and deficiency of the dorsalis pedis artery. There was a trend toward difference in the prevalence of deficiency of the dorsalis pedis artery in the clubfeet that required surgery (54%) compared with those that did not (20%), suggesting that dorsalis pedis artery deficiency may be more prevalent among clubfeet with greater deformity.

Necrosis Leading to Amputation Following Clubfoot Surgery

Amputation after clubfoot surgery is a rare and catastrophic complication. This case report involves an amputation necessitated by postoperative necrosis on the medial side of the foot. To our knowledge, only one brief published report of necrosis following clubfoot surgery exists in the literature, and that report contains little clinical information. Although we know of several additional cases of necrosis following clubfoot surgery, the details of these cases remain unavailable to us for publication. The clubfoot deformity is almost always associated with vascular deficiencies involving the anterior tibial and dorsalis pedis arteries, as well as their derivatives. Since the area of necrosis in this case report coincided with the anatomic distribution of the derivatives of the congenitally reduced or absent dorsalis pedis artery, we suggest that insufficient blood flow to the dorsal and medial sides of the foot, and to the hallux contributed to the necrosis. In our opinion, the surgeon should assume that an abnormal vascular pattern, as described here, is present unless proven otherwise.

The Epiblast Origin of Avian Somite Cells

Our laboratory has been engaged in the study of the acquisition by prospective somite cells of the developmental commitment to form somites. It was shown by the explantation of the so-called unsegmented somite meso-derm (the segmental plate) of chicken and Japanese quail embryos that the entire segmental plate was already committed to somite formation (Sandor and Amels, 1970; Packard and Jacobson, 1976; Sandor and Fazakas-Todea, 1980) and, furthermore, that the future somite pattern was already specified (Packard, 1978; 1980a; 1980b). I suggested at that time that the segmental plate contained about 10 to 12 “prospective somites” that were converted to definitive somites by the process of cleavage (Packard, 1978; 1980a). At about this time Meier (1979) discovered that a segmental pattern could be distinquished on the chick segmental plate through the use of stereo scanning electron microscopy. This pattern consisted of 10 to 12 tandem circular cellular domains that he termed “somitomeres.” Subsequent collaborative efforts between us demonstrated that somitomeres and prospective somites were one and the same and that these somitomeres became somites through a process of compaction (Packard and Meier, 1983; 1984; Cheney and Lash, 1984; Lash, 1985). Recent studies have suggested that the somitomere pattern may be adjusted to some extent following experimental manipulations (Packard, 1986).