Talus bone

The anklebone ( Syn roll leg, astragalus, talus med ) is a short bone and part of the tarsus and ankle. It is located between the ankle fork ( mortise ) and calcaneus ( calcaneus ), and connects the foot with the leg.

Construction

The talus consists of the body (corpus tali ), the neck ( collum tali ) and the talus head (caput tali ).

On the top of the talus is the anklebone role ( talar dome ). In the side-view the anklebone role is convex, the curvature being front than the rear. In the front view, however, shows a concavity, the role is centered arched by the prominent Seiträndern and adjusts for easy central protrusion of the tibial end. Thereby, the tibial part is additionally secured and guided in the ankle fork. The shin role is arched slightly narrower and less in the posterior part, more tilting movements of the ankle are in accordance with Fußbeugung possible. In contrast, the shin role is wider than the front low ankle fork and thus in the normal state safely fitted with strain of the syndesmosis. This leads to a high stability of the ankle joint in the normal stand

Medial to the talar dome is the comma-shaped articular surface of the medial malleolus ( medial malleolus facies ). From this joint surface goes to the back of the posterior process of the talus from. Lateral to the talar dome is the triangular articular surface of the lateral malleolus ( malleolus lateralis facies ). From this joint surface goes from the outside of the lateral process of the talus.

On the talus head is the articular surface for the scaphoid ( navicular ). This articular surface is as facies navicular articular referred. Here the spherical head is in the concave articular surface of the scaphoid, causing the talonavicular joint is formed. The articular surface is part of the anterior division of the lower ankle (USG ).

On the back is a pronounced extension, the posterior process of the talus. This is divided by a groove ( sulcus ), through which the tendon of the long running Großzehenbeugers ( sulcus musculi tendinis flexoris hallucis longus ). The lateral portion ( tubercle lateral processus posterioris tali ) is much more prominent and can be used as os trigonum view constitute an independent accessory bone, which is found in 13% of people. On the lateral aspect of the posterior portion of the outer ligaments inserted.

On the bottom there are the following three joint surfaces that are in contact with the calcaneus:

• Facies anterior articular calcanea
• Facies articular calcanea media
• Facies posterior articular calcanea

Between the articular facies calcanea media and facies posterior articular calcanea is a furrow, which is called the sulcus tali. Together with a corresponding groove of the heel bone ( calcaneus sulcus ) makes this furrow the sinus tarsi.

In even-toed ungulates of the talus has two castors. The upper joint role ( trochlea tali proximalis ) forms the articulated connection to the pivot screw of the tibia ( tibial cochlea ) and the lower joint role ( trochlea tali distalis ) articulates with the os tarsi centrale and quartum of the ankle.

Anomalies

These include:

• Talusspalte, incomplete fusion of the embryonic nuclear facilities.
• Misalignments talus verticalis
• Talus obliquus.

Fractures

Broken bones ( fractures ) of the talus are rare and account for only 0.32 % of all fractures and only 3.4 % of all fractures of the foot. In children talus fractures are virtually not available. The reasons are usually falls from heights or accidents with high energy. The first case series have been described during the world wars, and were mostly pilots who had bailed out, and parachutists, where even the name aviator 's astragalus stems ( flyer anklebone ).

Most common are the Talushalsbrüche between the distal and proximal talar head Talusrolle. this usually requires a forced dorsiflexion of the foot, usually combined with a supination - pronation or ( why accompanying ankle fractures are not uncommon ). For the Talushalsbrüche the classification is very often used by Hawkins:

• ° 1 - undisplaced Talushalsfraktur
• ° 2 - displacement with dislocation of the head of the talus with the calcaneus against the Talusrolle
• ° 3 - The proximal fragment ( Talusrolle ) dislocated completely backwards
• ° 4 - Both fragments are dislocated, the proximal fragment to the rear and the distal fragment is at least partially anteriorly.

The treatment of a bone fracture of the talus will depend on the location and severity of the fracture. In a break with no displacement of the broken ends is one of the foot usually in a below-knee plaster quiet. Are the fractured ends is displaced ( dislocated ), usually comes a surgical method (osteosynthesis ) are used. The risk of circulatory disturbance with subsequent osteonecrosis of the talar body is mainly in shifted or mehrfragmentären fractures very large, so a long relief phase after surgery is necessary. Especially with snowboarders can cause a fracture of the lateral process of the talus, which is called snowboarder 's ankle.

An os trigonum to the back of the ankle bone is an accessory bone that arises due to the plant or the result of an avulsion fracture of the tubercle lateral processus posterioris tali may be, by train of there advertisements from the rear portion of the outer ligaments ( ligament posterior talofibular ) at Supinationsverletzungen of the upper ankle joint.

An early frequently used method in mehrfragmentären fractures of the talus was its complete removal ( Astragalektomie ). This however remains an often painful limitation of movement with disruption of the normal foot biomechanics. In general, an anatomical reconstruction as possible is sought today.