THE ANATOMICAL STUDY OF POPLITEAL ARTERY AND ITS VARIATIONS

Address for Correspondence: Dr. J. Sujitha Jacinth, Assistant professor, Department of Anatomy, RMMCH, Annamalai University, Chidambaram, India. E-Mail: sujitha_jaf@rediffmail.com Introduction & aim: Anatomical variations in the arterial system are very common. In spite of advanced invasive techniques, knowledge of variations still remains limited. One such artery showing variations is the popliteal artery. Limb-threatening sequelae ensue from its damage. The aim of the study encompasses gaining knowledge on the anatomy of Popliteal artery with respect to its commencement, termination, branching pattern & its relation with surrounding structures mainly the muscles in the Popliteal fossa with a view of helping surgeons from various fields while performing surgery in this region. Comparison with results from previous studies on the popliteal artery was also planned. Materials and Methods: The study was carried out in 50 lower limbs of 25 well embalmed cadavers of South Indian origin irrespective of age and sex. None of the limbs showed any evidence of previous knee surgery. Results: Popliteal artery was the continuation of femoral artery. The level of termination in relation to the Popliteus muscle was high in one case and in the middle in another case. Popliteal artery terminated into anterior tibial and posterior tibial arteries. Arterial trifurcation was unobserved. Course was found to be normal with the Popliteal vein and Tibial nerve lying lateral to the artery in the upper part of popliteal fossa and medial to it in the lower part by crossing superficial to it. Third head of Gastrocnemius or aberrant band was not found. Conclusion: This study provides information vital to the successful accomplishment of surgical, radiological or interventional procedures to be carried out in the vicinity of the vessel.

Popliteal artery separately, giving a trifurcation.In the upper part of the popliteal fossa, Popliteal vein and Tibial nerve are posterolateral to the artery, then crosses the artery and becomes superficial to it .In the lower part both are medial to the artery.The vein is adherent to the artery throughout its course [1].
The site of passage of this artery through the adductor hiatus is a common area for atherosclerotic stenosis and occlusion probably as a result of repeated injury to the vessel in the hiatus.The anatomical relationships between Popliteal artery and surrounding structures are important.Arterial entrapment by neighboring muscles and tendons may occur due to variations that occur during the developmental stages.The Popliteal artery is relatively tethered to the Adductor magnus and distally by the fascia related to Soleus and is therefore vulnerable to traction during knee surgeries for example, dislocation.It passes medially beneath the medial head of Gastrocnemius muscle; contraction of which may occlude the artery and lead to vascular insufficiency.Extrinsic vascular compression causes chronic vascular microtrauma, early arteriosclerosis and thrombus formation [2].The entrapment of the Popliteal artery above the bifurcation level due to an anatomical anomaly is called "Popliteal Artery Entrapment Syndrome" [3].Stuart PTA [4] first published the clinical and radiological report about this syndrome as early as 1879.
The arterial variations may be due to any embryological defects, racial variance, or even acquired in nature.Szpinda N et al [5] described that the variations of popliteal artery are related to the combination of Sciatic and Primary femoral arteries which grow into the primodium of the lower limb.Awareness of these variations is important to perform surgical procedures like femoral distal end or proximal tibial or fibular fracture surgery, total knee arthroplasty, and especially in surgical interventions performed for Popliteal artery aneurysms or percutaneous vascular reconstruction in the lower extremities.Involvement of variant arteries during surgeries can lead to arterial complications like transection, fistula formation, pseudoaneurysms and thrombosis which may lead to limb or life threatening outcomes.
The purpose of this study is to describe anatomical variations of the Popliteal artery enabling it as a guide line for orthopaedicians, vascular surgeons and radiologists to some extent.
The   Yildiz et al [16] commented that high-origin of Anterior tibial artery from the Popliteal artery was about 1.2% to 6%.These high origins are vulnerable to arterial complications, including transection, fistula formation, pseudoaneurysm, thrombosis during orthopedic procedures such as high tibial osteotomy, revision total knee arthroplasty, lateral meniscal repair, posterior cruciate ligament interventional procedure in the Popliteal artery and its tibial branches.Tindall et al [17] observed that in all patients with high origin of the Anterior tibial artery, the artery was in direct contact with the posterior aspect of the tibia, in this variation using sharp instruments during knee procedures may be vulnerable.
Colborn et al [18] reported the splitting of the Popliteal artery into three branches in about 3% and also agenesis of the Popliteal artery.In this case, the Anterior tibial and Peroneal arteries originated distally from multiple collateral channels around the knee.and Orme [19] observed 3.2% of cases of trifurcation of the Popliteal artery in their angiographic study and also hypoplastic and aplastic infra Popliteal vessels.Z.A. Aktan et al [20] reported that the presence of an aberrant accessory head of Gastrocnem ius was higher in Turkish than Japanese people.In Japanese people, the frequency rate of the third head of Gastrocnemius muscle was 5.5% .This has been reported to be high in comparison with other nationalities (2.9-3.4%)but the presence of an aberrant accessory head of Gastrocnemius was observed higher than Japanese people in Turkish people with 6.5%.In this study, the Popliteal artery was lateral to border of the Popliteus muscle.According to type 3, the Popliteal artery, bifurcated at the proximal border of the Popliteus muscle into the anterior branch which descended at the ventral surface of the Popliteus muscle and continued as Anterior tibial artery between the muscle and posterior surface of tibia, the posterior branch continued as the posterior peroneotibial trunk at the dorsal surface of the Popliteus muscle.Bergman RA et al [10] reported that high division with the anterior peroneal trunk is more frequently seen in the right extremity, while high division of the Popliteal artery with the usual pattern frequented the left side.It is also mentioned that if variation occurs on one side, one is likely to observe presence of variation on the other side also.Lippert H et al [11] classified the branching patterns of Popliteal artery according to the level and sequence of branching of the Anterior tibial, Posterior tibial and Peroneal arteries.According to this classification, the division of the Popliteal artery (below the tibial plateau) was considerd as normal level (Type 1).In Type 2, branching pattern of the Popliteal artery occurs when one of the branches arise above the tibial plateau.Kim et al [12] angiographically classified the branching patterns of the Popliteal artery in 472 limbs.Angiographically the borders of Popliteus cannot be determined accurately, hence, the tibial plateau was used as the reference point.According to this classification, the division of the Popliteal artery was at the normal level (below the tibial plateau) in type 1 branching pattern of the Popliteal artery.In Type 2, branching pattern of the Popliteal artery was of one of the branches that arose above the tibial plateau.Type 3 branching pattern involved hypoplasia or aplasia of one or more of the infra Popliteal vessels with altered arterial supply to the foot.In a study conducted by Zuhal Ozgur et al [13], Anterior tibial artery was found to have high origin in 1.2% and was lying posterior to the Popliteus muscle.Arterial trifurcation was also observed in 3.2% of their study.
Trotter M [14] reported a ventral course of Anterior tibial artery in 42% of high-origin cases.Kil SW et al [15] noted that the course of Anterior tibial artery could be either from the ventral Soumya Philippose, J. Sujitha Jacinth, V. Muniappan.THE ANATOMICAL STUDY OF POPLITEAL ARTERY AND ITS VARIATIONS.
Popliteal vein in four specimens (8.7%) and it was deep to Popliteal vein in three specimens in the popliteal fossa (6.5%).Haidar.S et al [21] reported that most common cause of Popliteal artery entrapment syndrome is related to medial head anomaly of Gastrocnemius.Gibson et al [22] reported an incidence of 3.8% in 86 postmortem limbs.The Plantaris tendon sometimes may be the reason for Popliteal artery entrapment syndrome.Di Marzo L et al [23] found the Popliteal artery was coursing around the medial head of Gastrocnemius muscle which was compressing it and had the aneurysmal changes distal to the external muscular compression.Elias D et al [24] stated that Popliteal artery entrapment syndrome refers to compression of the Popliteal artery caused by the anatomical abnormalities in the popliteal fossa.Popliteal artery might be trapped by neighbouring muscles and tendons due to variations that occur during embryologic development of muscles and arteries.Dar AM et al [25] noticed that Popliteal artery was tethered at the Adductor magnus hiatus and distally by the fascia related to Soleus.It is therefore vulnerable to traction during knee injuries, e.g.dislocation.The knowledge of branching pattern of the Popliteal artery is Important for surgical interventions in the Popliteal region in order to minimize undesired hemorrhage and surgical complications due to anatomical variations.Orthopaedicians doing knee joint surgery and total knee arthroplasty, surgeons correcting Popliteal artery aneurysms and radiologists performing angiographic studies should be aware of these anatomical variations.These variations are compared with the earlier data and it is concluded that variations in branching pattern of the Popliteal artery are frequent rather than exceptions.

INTRODUCTION
International Journal of Anatomy and Research, Int J Anat Res 2017, Vol 5(4.3):4679-85.ISSN 2321-4287 DOI: https://dx.doi.org/10.16965/ijar.2017.435proximal to the popliteus muscle.Anterior tibial artery then may descend anterior or posterior to the muscle.The termination was considered "high" if it divides at the upper border of the popliteus and as "low" if it divides below from the lower border of popliteus muscle.And also the Peroneal artery may branch high from the Posterior tibial artery or may even branch from Popliteal artery is the continuation of Femoral artery after passing through the fifth osseoaponeurotic opening of the Adductor magnus.It descends laterally to the intercondylar fossa and bifurcates at the lower border of Popliteus muscle into Anterior and Posterior tibial arteries.It may divide into terminal branches study of Popliteal artery was carried out in 50 lower limbs of 25 well embalmed cadavers, in the Department of Anatomy, Amala Institute of Medical Sciences, Trichur and Department of Anatomy, Rajah Muthiah Medical College, Annamalai university, Chidambaram.The study was conducted irrespective of age and sex.Lower limbs with previous knee surgery were excluded.The gross dissection was done by following the guidelines of Cunningham's manual of practical anatomy (vol-1)[6].After the skin was incised the popliteal fossa was exposed through the posterior approach by identifying the muscles forming the boundaries of the fossa.The Tibial nerve, Common peroneal nerve, Popliteal vein were identified and then Popliteal artery was traced up to its terminal branches on both sides.The study was carried out under the following parameters, A. Origin, B. Level and mode of termination, C. Variation in the branches, D. Relation with Tibial nerve and Popliteal vein.MATERIALS AND METHODSRESULTSOrigin of thePopliteal artery: The Popliteal artery was the continuation of femoral artery from the fifth osseoaponeurotic opening of adductor magnus in all the 50 specimens studied.Level of termination of the Popliteal artery: The level of termination of Popliteal artery in relation to Popliteus muscle was observed in all the specimens as shown in table1.The level of termination was found to be normal in 48 specimens (96%) where it terminated at the lower border of the Popliteus muscle as shown in fig.1.It was high in 1 specimen (2%);where the termination was at the upper border of Popliteus as shown in fig.2.It was mid termination in 1 specimen (2%); at the middle of Popliteus muscle as shown in fig.3.Mode of termination of Popliteal artery: In all the 50 specimens studied the Popliteal Soumya Philippose, J. Sujitha Jacinth, V. Muniappan.THE ANATOMICAL STUDY OF POPLITEAL ARTERY AND ITS VARIATIONS.artery terminated into Anterior tibial and Posterior tibial arteries.Trifurcation of the artery was not observed.Course of Popliteal artery: In all the 50 specimens studied, Popliteal artery entered the popliteal fossa through the fifth osseoaponeurotic opening in the Adductor magnus.In 48 specimens, the artery had termination at the lower border of Popliteus muscle.The artery passed downward and laterally in close contact with the floor of fossa lying between two heads of Gastrocnemius and superficial to Popliteus muscle.Then it descended laterally inclining obliquely to distal border of Popliteus muscle, where it divided into Anterior tibial and Posterior tibial arteries.Relation of Popliteal artery to Popliteal vein and Tibial nerve: In all the specimens studied, Popliteal vein and Tibial nerve were lateral to the artery in the upper part of the popliteal fossa, then crossed the artery and was superficial to it.In the lower part, vein and nerve were medial to the artery.The vein was adherent to the artery throughout its course.Relation of Popliteal artery to medial head of Gastrocnemius: Popliteal artery was lateral to the medial head of Gastrocnemius in all the specimens studied.No evidence of third head of Gastrocnemius or aberrant band was noticed.Relation of the terminal branches to Popliteus muscle in high termination of Popliteal artery: In one specimen of high termination, Anterior tibial artery and Posterior tibial artery coursed distally anterior to Popliteus muscle.
absolutely essential.Computed Tomography, Angiography and Magnetic Resonance Image gives the detailed anatomy of the popliteal region well enough to reveal the cause of arterial entrapment.Early planning of Magnatic Resonance angiography, helps prevent delay in diagnosis.If the patient has Popliteal artery entrapment syndrome, the most common aetiology is anomaly of medial head of gastrocnemius.The contralateral popliteal artery should also be examined as there is a 28% probability of variation to occur on the opposite side.Despite improvements in vascular surgical techniques, Popliteal vascular injuries and Popliteal artery aneurysms continue to be potentially dangerous lesions with high percentage of leg amputations.The material reported here includes a review of the basic anatomic relationship of the Popliteal artery with its surrounding structures and its variation in the branching pattern.Awareness of these variations is crucial for evaluation of the lower extremity arteriograms and has clinical implications for vascular surgeons and interventional radiologists.Thus the present study is an attempt to add to the existing knowledge of the Popliteal artery and its variations in the branching pattern.Clinically, Popliteal artery entrapment syndrome should be kept in mind when the patient has intermittent leg pain, coldness or pallor in the lower limb.Early detection of the condition is CONCLUSION Conflicts of Interests: None