The Anatomic Study On Morphous And Blood Supply Of The Talus

Objective: To research the morphology and blood supply of talus and its effect on the stability of ankle joint in order to provide theoretic evidence for the prevention and treatment of talar disease.Methods: 20 feet of foot specimens of adult corpse without knowing clinical vascular disease were provided by Anatomic Department of Jilin University, which had been perfused by colorful dabbling chemical preparation (engineering plastics). The parenchymas of the specimens were removed by hands after all the specimens were corroded by 15% NaOH and saturated NaClO solution. The peripheral vessels of ankle joint were dissected carefully under binocular microscope for observing the blood supply of talus. After the talus had been dissected and dissociated, the length and width and height of the talus and the anterior width and posterior width and height of trochlea of talus and the length of medial and lateral malleolar facet were measured by sliding caliper with the precision by 0.01mm. The datas measured were kept two decimals. The data was analyzed by SPSS software.Results: The morphologic study of talus showed that talus could be divided into three parts including head, neck and body. The 60~70% of talus surface was covered by cartilage without muscle cohering. 7 articular surfaces were formed between the talus and its neighbor bones. All the measured data to the talus were expressed by x±s(min~max)mm. the details was : The length of talus was 56.02±2.16mm(52.35~58.34 mm), the height of talus was 32.62±2.68mm(27.63~36.50 mm),the width of talus was 43.09±3.27mm( 37.40~50.28mm),the anterior width of the trochlea of talus was 30.05±22.84mm ( 2 6 . 4 7 ~ 3 5 . 4 3 m m ), the posterior width of the trochlea of talus was 2 1 . 9 7±1 . 8 3 m m(19.60~26.32mm), the height of trochlea of talus was 9.43±1.18mm(7.99~11.23mm),the length of medial malleolar facet was 32. 50±2.63mm(27.75~36.48 mm)and the length of lateral malleolar facet was 29.36±2.51mm(25.76~33.12mm).From the study on blood supply of talus, we attained a result that talus was supplied by the branches arising from three main arteries including anterior tibial artery and the posterior tibial artery and peroneal artery, and extensive vascular anastomosis among them. The anterior tibial artery sends out branches to the talus at the level of the ankle joint, including medial anterior malleolar artery and lateral anterior malleolar artery. Medial tarsal arteries and lateral tarsal artery were below them. The superior arteries of the neck and the tarsal sinus artery were issued from the above small branches. The posterior tibial artery issued posterior tubercle arterial branch and deltoid branch and the tarsal canal artery to provide the blood supply of the talus along its way from proximal end to distal end. The peroneal artery sent out two branches including perforating branch and posterior tubercle branch to provide the blood supply for the talus. We found from specimens that these branches arised from the anterior tibial artery and the posterior tibial artery and peroneal artery coincided extensively each other to form arterial rete to supply the blood for the talus and the shape of vascular anastomosis is different. The vascular anastomosis were made up of by three main parts including the one part formed between the tarsal sinus artery and the tarsal canal artery, another part was the posterior process of talus between two calcaneal branches issued from the posterior tibial artery and peroneal artery, the third part was the arterial rete in periost formed among the superior arteries of the neck and the distal tarsal sinus artery and the deltoid branch.Conclusion: From the result of measurement to the anatomic morphology of the talus, we found that the talar body is an irregular cube characterized by wide in the front and narrow at back. It has 4 surfaces including upward, inside, outside and undersurface. The trochlea of talus was made up of the three surfaces before. The upper surface was constructed to an articulus with under joint surface of the tibia. The two edges of the upper surface eminentiaed little and the middle part of it was like a supersulcus in a front-to-back direction. The upper part of the inner surface was the articular facet of medial malleolus. The down rough part of it was cohering area of the fiber in deep layer triangular ligament. The triangulate outside surface was articular facet of lateral malleolus and the peak area outstanding of it was named lateral process of talus. A cavate rhombic articular facet in the undersurface of the talus was named facies articulares posterior calcanei. The posterior extremity of body of talus outstanding backward was named posterior process of talus which was divided by sulcus for tendon of flexor hallucis longus into two parts incluing medial tubercle and lateral tubercle. The talus plays an important role in biomechanics of the gambrel although there wasn't muscle attached to it. The gravity of human body and the stress produced by peroneal muscle when the gambrel plant flexed and dorsifled all were passed from the talus to other bones of foot. Moreover, the talus was constructed to the top of the arcus pedis longitudinalis, which could absorb the shake from the ground and play a role by ballbearing in articular of the gambrel. From the talus's rotation as the axle in the condition of plantar flexion and dorsifl and introversion and extroversion, we could increase the stability and flexibility of the foot when we walked. When the gambrel was in condition of dorsifl, the wide front of the trochlea of the talus could enter the ankle mortise jogged tightly. The body of talus could hardly move, at this time, the gambrel was in relative stable condition. When the ankle was in condition of plantar flexion, on the one hand, the narrow posterior part of the trochlea of the talus contacted with the ankle mortise and some vacant space was appeared around the two sides of the trochlea of the talus and ankle mortise at this time. It would make the body of the talus be in a relative unstable state that the body of talus could waggle slightly in the ankle mortise. On the other hand, due to the length of medial malleolar facet was obviously bigger than that of lateral malleolar facet, the lateral malleolar facet of the trochlea could have the chance to be separated from the ankle mortise when the talus moved forward. But the medial malleolar facet still keep contacting with ankle mortise at this time, So the stress suffered from two sides couldn't be kept balance and the lability of the ankle joint was increased. From above, we could draw a conclusion that the talus is easily to be injured when the ankle is in condition of plantar flexion. The talus didn't have independent nourishing blood vessel, it was only supplied by the blood supply distributed in the incrassate ligament and articular capsule around it. The blood supply from the head and neck area of the talus was more abundant than from the body of the talus.We could observe that the blood supply of the talus was from branches of the three main arteries of the leg including the posterior tibial artery, dorsalis pedis artery and peroneal artery, that was the superior arteries of the neck,the proximal and distal tarsal sinus artery, deltoid branch and the tarsal canal artery, posterior tubercle arterial plexus and peroneal artery perforating.These branches coincided each other to form arterial rete of talus to supply the blood for corresponding area of the talus. The blood supply of the talus could be destroyed by the talar damage and improper manipulation and avascular necrosis of the talus was resulted in.Through the research on the morphology and blood supply of talus and refernce to the study of other scholars abroad and domestic in this area, we further demonstrated that the morphology of talus mainly determined the occurrence of talus injury when the ankle was in the condition of plantar flexion. Meantime, it is commonly considered that the blood vessels supplying talus were easily injured when the fracture and dislocation of talus happened. Moreover, the contunding and swelling of local parenchyma and crushing in the fracture and dislocation of talus would also hinder the blood supply of talus. In operation, the improper processing to surrounding parenchyma would lead to Diaz disease. Therefore, in the treatment of talar injury, we should protect the talar blood supply for avioding Diaz disease and the dysfunction of ankle joint.