ANATOMICAL STUDY OF POPLITEAL ARTERY BRANCHING PATTERNS AND SURGICAL CONSIDERATIONS

Address for Correspondence: Dr. Rafael Cisne, Department of Morphology – Biomedical Institute – Fluminense Federal University, 101 Prof. Ernani Mello St., PC: 24210-150, Niterói, RJ – Brazil. Phone 55-21-26292332 – Fax: 55-21-23292414 E-Mail: rafael.cisne@gmail.com Background: The pattern of popliteal artery branching and its variations still subject for discussions due to several procedures performed in the popliteal fossa by vascular surgeons and interventional radiologists daily. The aim of this survey is to describe and quantify these variations comparing the results to the data found in the literature. Material and Methods: Twenty one anatomical specimens of the Department of Morphology from Fluminense Federal University, preserved in 10% formalin aqueous solution, were used in this study. Results: From those specimens, 17 (80.95%) had the most common pattern which is anterior tibial artery (AT) arising first followed by bifurcation of tibial–peroneal trunk in the posterior tibial artery (PT) and peroneal artery (PR); 3 (14.28%) had the trifurcation pattern; and 1 (4.77%) had the PT as first branch and anterior tibialperoneal trunk leading to AT and PR arteries posteriorly. Conclusions: The results showed low frequency of the common pattern when compared to the literature and revealed the relevance of the trifurcation pattern. The relative position of the frequency of this pattern matches the results of other studies.

The aim of this survey is to describe and quantify these variations comparing the results to the data found in literature based on the Kim et al classification [6].
The success of surgical procedures such as total knee replacement, ligament reconstruction, resection and vascular reconstruction, as well as radiological procedures, includes knowledge of the popliteal artery branching pattern and its variations [1][2][3][4][5].The most frequent pattern consists of the anterior tibial artery (AT) arisingfirst, followed by the bifurcation of tibialperoneal trunk in posterior tibial artery (PT) and Twenty one anatomical specimens of the Department of Morphology from Fluminense Federal University, preserved in 10% formalin aqueous solution, were used in this study.The specimens were studied by gross anatomy dissection according to the Helsinki Declaration and approved by the Scientific Council.According to the classification of Kim et al (6) , were considered the distance between medial tibial plateau and arising at first popliteal artery branch (distance A), the posterior tibial-peroneal trunk length (distance B), the distance between first popliteal branch and its bifurcation (distance C) and the anterior tibial-peroneal trunk length (distance D).For such measurements a digital caliper rule was utilized.

MATERIALS AND METHODS
The 21 anatomical specimens were classified by category I proposed by Kim et al [6]: normal level of popliteal artery branching.This means that, no specimen showed emission of arteries at the level of the femorotibial joint or above.We found all 3 types of division on this level (IA, IB, and IC) that are evidenced in Table 2.These frequencies were found: 80.95% (n=17) for the most common pattern; 14.28% (n=3) for trifurcation; 4.77% (n=1) for the emission of posterior tibial as the first branch and subsequent exit of the fibular and anterior tibial arteries by division of the anterior tibiofibular trunk (Table 1).

RESULTS
Table The distance A had an average of 6.2cm ± 1.37.The distance B averaged 2.2 cm ± 1.4.The distance C appears only in cases of trifurcation (IB) and should be equal to or less than 0.5cm according to the criteria of Adachi [19].The only value of distance D found was equal to 1cm.The frequency of the pattern IA (80.95%) is lower than all frequencies considered in the review by Kropman et al (7) .For this pattern, Kim et al. obtained 92.2%.The most remarkable, however, is not the most common pattern but the second most prevalent pattern.Trifurcation (Figure 1) is one of the most prevalent variations [6,7,20,21].Its frequency in the literature ranges from 6.0% (Davies et al, 1989) [22] to 1.5% (Kil & Jung, 2009) [8].Not even studies with a lower prevalence of the pattern IA presented values as expressive as this study, such as Mavili et al in 2011, which found 84.4% for the common pattern and 5.4% for trifurcation [9].Probably, this is due to the patterns of category II of Kim et al [6], high tibiofibular division of the popliteal artery branch, which is representative in the literature [6,8,9,14,16,23].In some cases, it exceeds trifurcation, 4.5% for the high division and 3.2% for trifurcation (Day & Orme, 2006) [10].
The anterior tibiofibular trunk (Figures 2 and 3), despite presenting an important frequency in this study, is a less expressive variant in the literature.Its values are sometimes exceeded by the frequency of Category III patterns [24], which is related to hypoplasia or proximal aplasia of  Arterial variations can be damaged through iatrogenic means if not properly documented.Therefore, the knowledge of variations in tibiofibular division pattern is indispensable for the exercise of surgical and radiological procedures in the proximal and distal regions of the lower limb, such as the treatment of popliteal artery aneurism, occlusive arterial disease and vascular injuries.On top of that, we must observe that trifurcation of the popliteal artery is maintained as a prominent pattern of tibiofibular division.

DISCUSSIONWanderley,Table 2 :
Annelise Passos Bispos, et al., ANATOMICAL STUDY OF POPLITEAL ARTERY BRANCHING PATTERNS AND SURGICAL CONSIDER-ATIONS.Normal-level Tibiofibular Division Patterns.trunk (most common pattern): emission of the anterior tibial at the level of the inferior border of the popliteal muscle and then the bifurcation of the tibiofibular trunk in tibial posterior A. and fibular A.Trifurcation: is the division of popliteal A. into anterior tibial A., posterior tibial A. and fibular A. within a distance equal to or less than 0.5 cm.There is no tibiofibular trunk formation.Anterior tibiofibular trunk: emission of the posterior tibial A. at the inferior border of the popliteal muscle and then bifurcation of the anterior tibiofibular trunk in anterior tibial A. and fibular A. one popliteal branch.However, this category does not necessarily point to a different pattern of division of the tibiofibular trunk, but an altered vascular organization to supply the areas of defective branch irrigation.