Anatomy of a duplicated human foot from a limb with fibular dimelia.

At birth, a patient presented with a right lower limb featuring preaxial polydactyly and fibular dimelia with a complete absence of the tibia. Radiographic studies of the patient's foot revealed a duplicated tarsus with eight metatarsals and toes. The three preaxial toes were surgically removed at 1 year of age. A hallux and four normal-appearing postaxial toes remained. The foot was amputated when the patient was 3 years old. Dissection of the amputated foot revealed that the muscles of the dorsum were normal, except that the tendon of the extensor hallucis brevis muscle inserted into both the hallux and toe 2, rather than only into the hallux. The few abnormalities observed among the muscles on the plantar surface of the foot included absence of the insertions of the tibialis posterior and the abductor hallucis muscles. In addition, the two heads of the adductor hallucis muscle inserted abnormally into the medial (tibial) side of metatarsal 1, rather than into the lateral side. These various muscular anomalies, in addition to the mirror duplication of the foot with the presence of only a single metatarsal 1, leads us to propose that this metatarsal probably represents two lateral (fibular) halves that form a laterally duplicated bone. Although the dorsalis pedis artery was present on the dorsal surface of the foot, most of its derivatives were absent. This artery did give rise to a supernumerary medial branch that ended abruptly in the connective tissue (presumably postsurgical scar) at the medial border of the foot. This branch may have represented a duplicated dorsalis pedis artery associated with the duplicated preaxial portion of the foot. The arteries on the plantar surface of the foot were normal. Even though some anomalies in the pattern of the cutaneous innervation were observed, the nerves of the foot were largely normal. The gross and radiographic anatomy of this specimen and the radiographic anatomy of the leg suggest that some teratogenic event occurred when developmental specification reached the level of the future knee. The teratogenic event, which probably occurred early in the fifth week of development, may have caused damage that led to a lateral duplication of both the leg and the foot with the absence of some of the most medial structures. Teratology 60:272-282, 1999.

Confirmation of arterial deficiencies in a limb with necrosis following clubfoot surgery.

This study describes postoperative necrosis of the hallux and first ray in a child with clubfoot. Arteriography performed on this child's lower limbs demonstrated, in the operated leg, hypoplasia of both the anterior and posterior tibial arteries and failure of the dorsalis pedis artery to traverse the tarsus and complete the deep plantar arch. Previously, congenital vascular deficiency was suggested to predispose such operated limbs to necrosis. These findings confirm the association between vascular deficiency and necrosis. In this present study, the metabolic demands of wound healing were sufficient in a limb with vascular deficiency to cause localized distal hypoperfusion leading to cyanosis and necrosis of the hallux and medial foot.

Hematomas and limb skeletal malformations in chicken embryos following exposure to 5-fluoro-2-deoxyuridine.

Vascular injury or interruption may play a role in vertebrate limb teratogenesis. Since 5-fluoro-2'-deoxyuridine (FdU) can cause vascular injury in the murine limb and skull prior to the appearance of skeletal malformations in these structures, we studied the effects of this chemical on skeletal development in the chick embryo and noted any vascular injury. The yolk sacs of day three chick embryos (Hamburger and Hamilton states 17-19) were injected with solutions of vary concentrations of FdU in saline. The embryos developed until the 10th day of incubation when they were fixed for study. Uninjected, saline injected, and sham injected control embryos were similarly fixed. Upon gross inspection, frequent diffuse and saccular hematomas, as well as fluid-filled blisters, were noted in the limbs of embryos treated with FdU. After the embryos were fixed and cleared, and the skeletons stained, significant skeletal malformations were observed in these limbs. Bony elements of both the upper and lower limbs were affected in at least some of the embryos. The combination of FdU-induced hematomas and blisters with associated skeletal malformations in the same regions of some embryos suggests a relationship between these phenomena.

Embryonic hypertension following exposure to teratogenic doses of 5-fluoro-2'-deoxyuridine.

The teratogenicity of 5-fluoro-2'-deoxyuridine (FdU) is well established. Previously, we have demonstrated that teratogenic doses of FdU produce hematomas and suggested that those hematomas produced skeletal malformations in chicken embryos. In this study, the cardiovascular effects of teratogenic doses of FdU in chicken embryos were studied. A dose of either 0.026 micrograms FdU or 0.030 micrograms FdU was injected into the yolk sacs of fertile chicken eggs containing embryos at Hamburger and Hamilton stages 17-19 of development. The embryos were then returned to the incubator. Aortic systolic and diastolic blood pressure, blood velocity and heart rate were measured at stages 21, 24 or 27 using a servonull system and Doppler ultrasound. In addition, mean arterial blood pressure, blood flow, and stroke volume were calculated from these data. Similar data were also recorded from uninjected and saline injected control embryos. Systolic and mean arterial blood pressures were significantly increased in FdU-treated embryos at stage 27. The other parameters measured or calculated were not significantly different from control embryos. Our study suggests that elevated systolic blood pressure in chicken embryos treated with FdU may lead to hematoma formation and subsequent birth defects.

Extent of duplication in lower-limb malformations suggests the time of the teratogenic insult.

Investigations of vertebrate limb development have suggested that a process called "specification" instructs the cells of the future limb as to which tissues they should form. This process proceeds in a wave-like manner, starting at the most proximal levels of the future limb and ending at its distal tip. Human limb specification probably occurs during the fourth and fifth weeks of development. It is proposed that human limb duplications result from errors of specification and, furthermore, that the more distal the duplication, the later the occurrence of the teratogenic event during the specification process. Therefore, among human lower limbs with duplications, one may be able to estimate the relative time of the teratogenic event by comparing the levels at which the duplications occur.

Consistent arterial abnormalities associated with a variety of congenital malformations of the human lower limb.

A number of seemingly unrelated congenital deformities of the lower limb have been presented which include clubfoot, fibular deficiency, tibial aplasia, and diplopodia. Although the bony morphology in these limbs is quite different, they all share a strikingly similar arterial pattern, that being deficiency or absence of the anterior tibial artery, and of its derivative, the dorsal pedis artery. Since all of these diverse conditions share a similar aberrant arterial pattern, we suspect that the arterial changes are important in the pathogenesis of those conditions. Study of the soft tissue anatomy of these specimens suggests that the etiologic teratogenic event occurred early in embryonic development. In those limbs that contain the remnant of a missing structure, it is concluded that injury occurred after the mesenchyme was instructed to form that structure. These are termed "post-specification" defects. In those circumstances where limb duplication occurs, the injury affected the signal before instruction of mesenchyme to develop into a specific structure was completed and these abnormalities are termed "pre-specification" malformations. The musculotendenous and neurologic abnormalities seem to be reactive to the pre-existing bony pattern.

The anatomy of a human foot with missing toes and reduplication of the hallux.

Detailed dissection of a malformed human foot was performed so that the skeletal and soft tissue anomalies in the foot could be compared and contrasted with those found in three previous specimens that we have dissected. The specimen described here consisted of a foot with a reduplicated hallux and two missing toes. Study of the bones revealed a wide medial metatarsal that articulated with a reduplicated hallux. There were two complete lateral toes with normal bones. Two toes and their metatarsals were missing with no remnants. The arterial pattern was similar to those seen previously by us. The dorsalis pedis artery was absent and the plantar arch was abnormal in that it did not terminate with a dorsal anastomosis. There was an extra lateral branch of the medial plantar artery. The digital arteries to the missing toes were also missing. The nerves of the foot were normal with the exception of an extra lateral branch from the medial plantar nerve. As with the arteries, the nerves to the missing toes were also missing. The muscles and tendons on the dorsal surface of the foot were all present but several of the tendons were inserted in abnormal locations in apparent response to the abnormal bone pattern. Most of the muscles and tendons of the plantar surface were present with the exception of the flexor hallucis longus and brevis muscles. Several of the remaining tendons apparently were influenced by the abnormal skeletal pattern and the missing muscles to become inserted on or near the replicated phalanges of the hallux. The anatomy of this specimen suggests that the teratogenic event occurred when specification of the limb bud mesoderm cells had progressed to the level of the distal tarsus and was located in the region that normally would have formed the metatarsals and phalanges of Toes 2 and 3. Further, we propose that the association between skeletal anomalies and arterial deficiencies has aetiological significance. We hypothesise that the abnormal arterial pattern put the limb at risk of teratogenic damage by reducing the number of collateral blood supply routes and that some event, such as extravasation of blood or embolisation, compromised the blood flow in the remaining blood vessels. These events could have resulted in both general shortening of the limb and the specific defects observed in this foot.

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.

Arterial abnormalities in talipes equinovarus as assessed by angiography and the Doppler technique.

Preoperative angiography in 30 uncorrected clubfeet demonstrated abnormal vascular patterns in all but two limbs with hypoplasia or premature termination of the anterior tibial and medial plantar arteries in the remainder. Postoperative Doppler studies in nine of the limbs with abnormal vessels indicated that these arteries were present. We suggest that the continuous-wave Doppler technique is less useful for identifying major arteries than either dissection or angiography. Furthermore, arterial dysgenesis may play a role in the etiology of clubfoot. Since the posterior tibial artery usually provides the sole arterial supply to the foot, this vessel must be preserved at surgery and during subsequent ankle dorsiflexion.

Soft tissue anomalies in a patient with congenital tibial aplasia and talo-calcaneal synchrondrosis.

We have carried out the third in a series of anatomical dissections of amputated congenitally deformed human limbs in an attempt to determine the etiological relationship between the bony and soft tissue anomalies. This specimen consisted of a limb with congenital tibial aplasia and an adducted foot with five toes. The arterial and nerve patterns were reminiscent of those seen previously by us. The arteries were characterized by absence of the anterior tibial artery and an incomplete plantar arch. The superficial peroneal nerve terminated at the ankle. Extra branches from the sural, deep peroneal, and medial plantar nerves supplied branches to the dorsum of the foot. There were two extra muscles in the leg. The remaining muscles were normal, with the exception that most muscles normally inserting on the plantar surface of the foot inserted instead into a common tendon sheet. The tibia was replaced by a tendinous band, and the talus and calcaneus were united by a complete synchondrosis. The contralateral limb clinically appeared to have a clubfoot. The combination of an absent anterior tibial artery and an incomplete plantar arch is consistent with our theory that a reduced number of vessels puts the embryonic limb at increased risk of congenital defects due to the reduction in the number of collateral blood routes. Some event, such as extravasation of blood or embolization, may concurrently or subsequently compromise blood flow in the remaining vessels. We have previously observed abnormal arterial patterns similar to that described above in limbs having absence of the tibia and in other patients having clubfeet. The presence of abnormal arterial patterns in a limb with absence of the tibia and a contralateral limb with clubfoot suggests that absent tibia and clubfoot may be etiologically related.

Arterial anatomy of chicken embryo and hatchling.

The arterial pattern in chicken hatchlings was investigated by microangiography and microscopic analysis of cleared specimens. The hatchling arterial pattern was found to resemble strongly the pattern that has been described for the adult chicken. Several minor variations in this pattern were found which were probably due to species, strain, or age differences. We also investigated the arterial pattern in chicken embryos aged 4.5 to 21 days of incubation. The hatchling pattern was fully developed by approximately 8 days of incubation. Some similarities were found to exist between the embryonic pattern in the chicken embryo and that described for the human embryo.

The anatomy of a congenitally short limb with clubfoot and ectrodactyly.

Previous studies have shown an association between an abnormal arterial pattern and bony malformations of the human lower limb. We have dissected and performed arteriography on a congenitally short limb with ectrodactyly in order to examine the relationship between arterial pattern and bony anomalies in another type of deformity. The bony anomalies were a combination of short femur, tibia and fibula, clubfoot with tarsal synostoses, metatarsal absence, ectrodactyly, and a bifid hallux. The arterial pattern was characterized by deficiency of the anterior tibial artery and absence of the plantar arch. Major muscular anomalies were noted in the foot only; the muscles of the missing toe were absent and any muscles that normally cross the midventral line were either missing or failed to cross the midline. The superficial peroneal nerve failed to enter the dorsum of the foot and its sensory distribution was assumed by an extra branch of the sural nerve. The most severe abnormalities of the bones, muscles, arteries, and nerves occurred near the midventral line of the foot. We hypothesize that the abnormal arterial pattern put the limb at risk of teratogenic damage by reducing the number of collateral blood supply routes. We suggest that some event, such as extravasation of blood or embolization, compromised the blood flow in the remaining blood vessels and that this event resulted in both a general shortening of the limb and the specific defects observed in the foot. We interpret the anatomy to be consistent with the vascular teratogenic event occurring near the midline of the foot during the fifth week of embryonic development.

Congenital tibial aplasia with preaxial polydactyly: soft tissue anatomy as a clue to teratogenesis.

We performed preoperative arteriography and postamputation dissection on a human limb having complete tibial aplasia and preaxial polydactyly. The tibia was replaced by a tendinous band with an attached connective tissue mass. In the leg, the muscles were normal. Muscles usually arising from the tibia arose from the tendinous band, Intrinsic muscles of the foot were absent where skeletal elements were absent and there were supernumerary muscles where there were supernumerary skeletal elements. The tendinous insertions of the muscles that originated in the leg followed the skeletal pattern of the foot. The nerves were normally distributed with the exception that extra branches innervated the supernumerary toes. Both the anterior tibial and peroneal arteries were smaller than normal and progressively reduced in size as they coursed distally and could not be identified below the ankle. The dorsalis pedis artery was absent. The other arteries of the leg and foot were normal with the exception of extra branches supplying the supernumerary toes. The anatomy indicates that the foot is probably a double posterior duplication. Such a defect implies abnormal specification of the foot pattern due to a prespecification event. The tibial remnant with normal leg soft tissues indicates normal specification of the leg pattern and subsequent interruption of tibial morphogenesis due to a postspecification event. The presence of these different types of malformations in the same limb may seem to be contradictory. We suggest, however, that a single teratogenic event occurring at one moment in time could cause combined pre- and postspecification malformations. We further suggest that a diminished anterior tibial artery reduced the number of vessels available for collateral circulation and thus put the limb at risk for subsequent malformation.

Congenital arterial malformations associated with clubfoot. A report of two cases.

Arteriograms were examined in three limbs of two patients who had talipes equinovarus. An abnormal arterial pattern characterized by severe diminution in the size of the anterior tibial artery and diminution or absence of the dorsalis pedis artery was evident. Inasmuch as one of these patients was preambulatory, the arterial malformation is congenital and would not have been acquired in walking. The relationship between the abnormal arterial and bony pattern in talipes equinovarus is comparable to that previously described for congenital absence of the fibula. A possible etiologic relationship between TEV and embryonic arterial accidents is suggested.

Ipsilateral supracondylar femur fractures following knee arthroplasty.

A retrospective study was performed to evaluate the treatment of five patients with prosthetic knee arthroplasty who sustained a supracondylar femoral fracture of the ipsilateral side. Four of the patients were initially treated by plaster immobilization or traction. Two of the four showed no signs of healing at three months postfracture and had to have open reduction and internal fixation. The fifth patient had primary open reduction and internal fixation. The three patients who were treated surgically regained their prefracture knee rating score. The two who were treated nonoperatively for their fracture had a significant loss in limb function and failed to regain their prefracture knee rating score. Open reduction and internal fixation of these fractures achieves the best results despite the complicating factors of in situ prosthetic components.

Vascular dysgenesis associated with skeletal dysplasia of the lower limb.

Three patients who had shortening or absence of the fibula were evaluated angiographically. An abnormal arterial pattern was found in all of the dysplastic limbs. This abnormality was characterized by persistence of an embryonic vascular pattern, absence of one of the normal arteries, and failure of formation of the plantar arch. In each patient there was a large posterior artery in the leg, termed the tibialis posterior superficialis.

Midline metatarsal dysplasia associated with absent fibula.

In 5 patients with congenital deficiency of the fibula, the degree of fibular deficiency ranged from unilaterally short to bilaterally absent. The patients each had at least one missing metatarsal and, in addition, dysplasia of a midline metatarsal. In view of these findings, some missing metatarsals associated with congenital fibular deficiency could be midline metatarsals. The abnormality could represent a deficiency acquired after the development of the embryonic limb bud cartilage models.