Feet and Ankles

Feet and Ankles

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Just as our hands help to set us apart from the all the animals including our nearest cousins the apes, so too to a lesser degree do our feet and ankles. After all, we are the only inhabitants of this world who walk flat footed and erect from the time we first learn to walk until we die. Most animals, including cats, dogs, and horses, all walk on what for us would be our toes. Even those few who do walk on their entire foot, such as chimps and gorillas, are not designed by nature to walk upright as their natural posture, but rather they walk bent over using their hands as a second set of feet. And just as our feet are similar to our hands in setting us apart, so too are our feet similar to our hands in bone structure. Even the names of the bones are similar, with tarsals taking the place of carpals and metatarsals taking the place of metacarpals. The difference is in the way they are formed, since our hands are designed to pick up and manipulate objects, while our feet are designed to take the weight of our bodies and spread it out between our heels and the balls of our feet through a series of arched shaped structures.

An x-ray study of the foot normally involves three films or views. The first picture is a frontal, or AP view where the foot is placed flat on the film and the x-ray tube or camera is commonly angled about 10 degrees to match the slope of the top of the foot. This shows the toes, or Phalanges, the Metatarsals which are five long bones which make up the majority of the front end of the foot, and the tarsals on the inside of the foot clearly separated. The second view commonly obtained is an oblique, or angle shot where the knee is rolled inwards so that the foot is at a 45 degree angle to the film with the inner edge of the foot resting on the film. This helps to separate the three metatarsals near the outer edge of the foot as well as the tarsals on that same side of the foot. The final x-ray commonly taken is a side shot, or lateral, to check the up and down alignment of the bones and any fragments.

Occasionally the doctor will be worried only about one or two of the toes, in which case we can do x-rays of just the toe that is hurt (though in my experience this is commonly only done for the big toe since that is the toe we use to push off with when we walk or run). The views used for this series of x-rays are generally the same as for the whole foot except that only the toe in question is x-rayed. The reason many doctors don't bother x-raying any toe other than the big toe is that many people cannot move their toes well enough to separate the toe that is hurt from the other toes.

At other times, the doctor may be worried most about your heel, especially if you've just jumped or fallen and landed flat footed. The main bone that makes up the heel of your foot is called the Calcaneus or Os Calsis, and is a sort of rounded block shaped bone that supports what weight that is not distributed to the ball of your foot. Generally only two views of the calcaneus are obtained. The side shot, or lateral view is a straight forward enough x-ray that is done the same as a lateral of your foot or ankle except that the x-ray is normally restricted to just the calcaneus itself. The other shot is what is normally referred to as an Axial shot, and can be done in one of two ways. The method I generally prefer places the x-ray film under the patient's ankle with the toes pointed straight up at the ceiling and the x-rays entering the foot at a 45 degree angle between the heel itself and the center of the arch. A second method which produces a film that is virtually identical has the patient's foot flat against the film and the x-rays entering the Achilles tendon area again at a 45 degree angle. The reason I'm not fond of this method is that to use it, the patient must generally be able to stand or to lie flat on their stomach, whereas the first method can be done with the patient either sitting down or laying on their backs.

The Ankle is the point where the two bones of the lower leg, the Tibia and Fibula, meet the top most bone in the foot, called the Talus. Again, just like the foot and the hand, three views are normally done for the ankle. The first is a straight frontal, or AP shot where the film is placed behind the ankle and the toes are pointed up at the ceiling. The second x-ray is an oblique or angled shot commonly called a Mortise View. This shot involves turning the for inwards about 20 to 45 degrees depending on what the doctor is interested in seeing while keeping the toes pulled up towards the body as much as possible. This position tends to separate the three main bones making up the ankle so that we can see if any thing is sticking into the space between the bones, as well as allowing us to see any fractures without the distracting superimposition found on the normal AP view. The third x-ray normally done is a side shot, or lateral. While the side shot can be done with either the inside edge of the foot against the film or the outside edge, it is more common to use the outside edge as the surface which is placed against the film for the simple reason that it is normally more comfortable and easier for the patient to roll their leg and hip in that direction. Either method works equally as well for the purpose of finding out what is wrong however.

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