The Anatomy of the Talus

The Topmost Bone of the Foot

In This Article

The talus is the bone at the top of the foot that serves as a perch for the tibia and holds the weight of the entire body. The talus is considered a short bone and is one of the main bones of the ankle. It is a little longer than 5 cm in women and a bit over 6 cm in men. Talus comes from the Latin word for dice, as Roman soldiers used this bone from horses to make dice for games of chance.

Anatomy

The talus is a very compact and hard bone making up a part of the ankle joint where the tibia (shin bone) and fibula meet the foot. It is found at the top of the foot and is one of seven tarsal bones. The talus is 5-6 cm long and is nearly covered with cartilage to help cushion the movements the talus makes as part of both the ankle and the foot.

The talus is connected to the tibia at the top (superior), the calcaneus to both the back (posterior) and below (inferior), the navicular to the front (anterior), and the cuboid below (inferior). Blood is supplied to the talus through the posterior tibial, anterior tibial, and peroneal arteries. The posterior tibial artery is the main blood supply for the talus.

The parts of the talus are the head that connects to the navicular, the neck, the dome that connects to the tibia, the posterior facet that connects to the calcaneus, and the anterior facet that connects to the cuboid. There are protuberances on the back and side called the posterior process and the lateral process. There is a depression under the talus called the sulcus tali.

Function

The talus is pivotal to the function of the ankle, literally. When viewed together within the ankle and in relation to the other tarsal bones, it has the look of a universal joint on a car's driveshaft. The talus works the same way, allowing the connecting bones of the ankle to slide around it in multiple directions while supporting weight.

The talus is the main bone that connects the ankle with the lower leg. The talus serves as the connection point for several bones and takes on a lot of force when twisting or sudden weight is applied to the foot and ankle.

Associated Conditions

Ankle fractures are often fractures of the talus. The most common injury is through a twisting motion that can lead to very small, painful fractures of the talus, as well as damage to the connective tissue and cartilage surrounding it.

Newer mechanisms of injury have increased the incidence of talus fractures as sports or vehicles have changed. Snowboarders, for example, have seen an increase in fractures of the lateral process of the talus. These types of injuries were once very rare and often overlooked because they can be subtle on an x-ray.

Severe ankle fractures or twisting can result in a fracture of the talus. Outside of twisting motion, it usually takes quite a bit of force to fracture the talus, which may occur due to falls from great heights or from head-on car accidents. Older people have a higher potential for talus fractures.

Until the 20th Century, talus fractures were rarely documented. In 1919, doctors noticed an increase of talus fractures that came from airplane crashes. The same types of injuries occur today in high-speed car accidents and falls from very high places.

Talus fractures are classified from type I to type IV:

  • Type I talus fractures have a clear vertical fracture line, but very little, if any, separation of the two parts of the talus and it remains in the proper anatomical position within the ankle. Only one of the three blood vessels supplying the talus is typically affected. A type I talus fracture usually heals well without any necrosis of the bone.
  • Type II talus fractures have a clear separation across the fracture, but the talus still remains mostly in place within the ankle. In a type II talus fracture, the bone can be reduced (put back together) almost always, but there can be some long term damage and possible necrosis of the bone. In this case, two out of the three arteries feeding the talus could be damaged.
  • Type III talus fractures have the same sort of separation as a type II fracture with the addition of an ankle dislocation. This means the position of the bones around the talus are affected and might not fit together the same way they would if there wasn't an injury. Disruption of all three blood vessels is common in a type III talus fracture and necrosis of the bone can occur.
  • Type IV talus fractures include not only the dislocation of the body of the talus (the posterior portion) from the calcaneus but also the separation of the head of the talus from the other tarsal bones anterior to it. This could be a subtle difference to a type III talus fracture and was not originally part of the classification system.

Regardless of the type of talus fracture, symptoms run in a similar vein. Pain, swelling and deformity of the ankle, inability to bear weight, decreased range of motion, and tenderness are the common symptoms of talus fractures.

Treatment of talus fractures depends on the severity and will include some combination of surgery, immobilization (a cast or brace), physical therapy, crutches or other weight relief, and pain relief. Long term complications of talus fractures can include arthritis and multiple surgeries.

Congenital vertical talus is a rare genetic deformity of the talus that happens in utero and is diagnosed at birth. Vertical talus is painless at birth, but if left untreated can become extremely painful for the patient. Usually, vertical talus is corrected with surgery at around nine months to a year of age. Prior to that age, some doctors might recommend trying nonsurgical treatments, such as special shoes or braces.

If vertical talus is not corrected during childhood, repairing it in adults is extremely difficult and will require multiple surgeries.

Rehabilitation

Injuries to the talus require high energy trauma and may take weeks to months to fully recover. Stable fractures, listed above as type I talus fractures, are those in which the bone is still in the proper anatomical position. Those are the only types of talus fractures that can reasonably be treated without surgery.

More severe talus fractures that are considered unstable, meaning the bones have shifted out of place, will require surgery to put the bones back where they belong and secure them. The bones will often be held in place with screws.

Because of the function of the talus, no weight can be applied to the talus during the beginning of the recovery period, which could be the first eight to twelve weeks. Weight reduction includes wearing a cast and using crutches or a knee scooter.

Despite the need to keep weight off of a healing talus, the doctor may encourage the patient to begin moving the ankle as soon as possible. In surgical cases, the doctor will probably suggest movement as soon as the wound heals. In nonsurgical cases, the doctor will probably suggest ankle motion as soon as the cast is removed.

Once it is possible to begin bearing weight on the ankle again, the doctor is likely to suggest a gradual introduction to weight bearing. Usually, this will include wearing an orthopedic boot to distribute weight across multiple areas in the foot and direct weight to higher on the leg.

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