Pulsatility index in the fetal anterior tibial artery during the second half of normal pregnancy.

The objective of this prospective study was to establish reference values for the pulsatility index in the fetal anterior tibial artery during the second half of pregnancy. Pulsed Doppler waveform analysis of 203 fetuses at 23-42 weeks of pregnancy was performed, each fetus being examined just once. There were neither fetal nor maternal complications detectable at the time of the examination. In the first 14 fetuses from which recordings were taken, Doppler examination was performed on both fetal legs in order to evaluate systematic differences between the right and left legs. Intraobserver variability was analyzed by repetition of the measurements by the same examiner in the first 130 cases. There was no difference between right and left tibial circulation. The repeatability coefficient, defined as the 95% range for the difference in two repeat measurements, was 1.08. The pulsatility index of the anterior tibial artery (50th centile) increased slightly from 3.29 at 23 weeks of pregnancy to 4.09 at 42 weeks. The 5th and 95th centiles were calculated, as was the 95% confidence interval of the 5th and 95th centiles. Examination of the fetal peripheral circulation during the second half of pregnancy is possible with a high degree of precision. Whether there are changes in peripheral arterial circulation in compromised fetuses remains to be evaluated.

Absence of the posterior tibial artery: implications for free transplants of the fibula.

A well-documented case of absence of the posterior tibial a. is reported. We have studied 40 personal case-records of dissection of the arteries of the leg in fresh corpses. This study allowed classification of the origins of the leg arteries from the popliteal a. into 7 groups. Several findings emerged: 1) the peroneal a. is constant, for phylogenetic and embryologic reasons, 2) the posterior tibial a. is absent in 1 to 5% of cases [1, 2, 4, 6-8] (Fig. 4), in which case the vascularisation of the fibula remains as normal (the proximal epiphysis of the fibula is vascularised by the anterior tibial a., the diaphysis and the distal epiphysis by the peroneal a.). Other anatomic variations may be found: trifurcation of the popliteal a., origin of the anterior tibial a. from the peroneal a., absence of the anterior tibial a., aplasia of the terminal portions of both the anterior and posterior tibial aa. In practice, absence of the posterior tibial a. can be demonstrated by arteriography and doppler ultrasound. We are dubious about the indications for arteriography, which is not always a risk-free examination, and therefore prefer doppler examination with ultrasound, which supplies adequate information in the majority of cases.

Study of the arterial vascularisation of the medial tibial condyle in the fetus.

Varus deformity of the knee is common in young children who have suffered from fulminating purpura. This study was directed at the anatomic features of the vascularisation of the upper end of the tibia that might account for such deformation. It was based on the dissection of 28 anatomic specimens prepared by injection of Indian ink into the vascular trunk. 16 specimens were diaphanised for better analysis of the intracartilaginous distribution of the vessels. The study showed that the vascularisation of the medial condyle of the tibia is poor and of terminal nature, which may explain the occurrence of ischemic growth disorders following fulminating purpura.

Anterior tibial artery: variation in origin and branching.

In a combined radiographic-anatomic study, the anterior tibial artery in a stillborn male was a branch of the posterior tibial at about its midpoint. It gave off an unusual lateral calcaneal vessel that coursed initially in the musculoperoneal canal. The variations are discussed in the context of the complex embryologic development of the blood supply to the lower limb.