Podiatric Imaging - X-rays

With the exception of dermatology, most doctors are treating conditions that they cannot see with the naked eye.  In order to overcome this hurdle, many different types of imaging techniques and instruments have been developed in order to allow the doctor direct visualization of the problem area.  Let’s discuss the imaging most often used in podiatry.

The most commonly used imaging technique in podiatry is radiographs, or x-rays.  Although there are many exceptions to this rule, most people who walk into a podiatrist’s office will get x-rays.  X-rays are the best to order when a patient’s main complaint could potentially involve the bones or joints.  X-rays give only two dimensional images, so it is necessary to take x-rays from multiple angles so that the doctor can mentally put the images together to form a three dimensional picture.  X-rays give the doctor important clues in figuring out the pain a person is experiencing.  Fractures, foot mal-alignment, and arthritis can be diagnosed with simple x-rays.  If a person has stepped on a foreign object, x-rays can help to locate the position of it.  X-rays also can help to push the doctor to order additional tests or refer out to a different specialist if certain signs are present suggesting disease like rheumatoid arthritis, peripheral arterial disease, or other systemic disease.  It may even be necessary to get an x-ray with a severely infected ingrown toenail to see if the infection has gotten into the bone.

 

A concern that some patients have is the radiation associated with x-rays.  This was a problem in past decades with more primitive x-ray machines.  However, modern x-ray machines minimize the scatter of x-rays by directing the beams directly at the target object and having a very short exposure time.  Lead is worn to protect against the small amount of scatter.  X-rays are avoided if the patient is currently pregnant.  You can be assured the amount of radiation received by the foot is very small.  In fact, an x-ray exposes you to the same amount of radiation you would receive by spending about 5 minutes in the sun.  When compared to tanning, sun-bathing, or going without sunscreen in the sun, the radiation of an x-ray is insignificant.

Even though x-rays show bones and joints very nicely, they do not show much in terms of muscles, tendons, ligaments, or blood flow.  In some complicated fractures, it may be hard to determine the extent of the fracture with only an x-ray.  In these cases, ultrasound, Magnetic Resonance Imaging (MRI), computed tomography (CT or CAT Scan), or bone scans may be used.  We will discuss each of these imaging techniques in the upcoming weeks.

Wound Debridement Continued

Let’s finish our discussion on the different types of debridement.

Mechanical debridement is another method to remove non-viable tissue. This is accomplished by applying wet to dry dressings. Normal gauze is soaked in some type of antibacterial solution and packed into the wound. Solutions may be simple saline, Dakin’s (a diluted version of bleach), or other antibacterial solutions. This wet gauze once packed into the wound is covered by dry gauze then wrapped. This dressing is changed every day. As the packed gauze is removed, dead tissue is removed with it. This is a very inexpensive way to keep a wound clean, ward off infection and allows for evaluation every day during dressing change. This dressing may be used prior to application of a Negative Pressure Wound VAC. However, dressing changes may be a very painful as they rip superficial tissue off.

Autolysis is another option for debridement. Autolysis means to let the body digest or get rid of bad tissue by its own means. The body produces digestive enzymes called MMP’s. MMP’s at the wound’s surface liquefy the dead tissue. In order to allow the MMP’s to work, an occlusive dressing is placed over the wound. Occlusive dressings are not permeable to air and they keep the wound isolated from the outside environment. Occlusive dressings are relatively controversial. Some feel that occluding a wound keeps fluid and possibly unknown pus in a wound. However, studies show occluding a wound keeps its pH low, which inhibits bacterial growth and promotes oxygen unloading from red blood cells. Autolytic debridement is a more advanced way to debride a wound and requires frequent evaluation and inspection.

All in all, each method of debridement has its place in wound therapy. Different physicians prefer different dressings depending on their experience and training. If you are currently working to heal a wound, work with your doctor to know which type of debridement is best for your situation.

Debridement of Diabetic Wounds

In light of our recent discussions on maggot therapy, I thought it would be wise to discuss different ways to debride diabetic wounds and their associated pros and cons. Wound care is continually being assessed for effectiveness and continues to evolve. This is a short review of some of the many options available.

The most obvious way to debride a wound is manually with a curette or scalpel blade. This is the mainstay of wound debridement due to its practicality and ease. This type of debridement can be done quickly in an office visit or bedside without any major equipment. It is cheap and fast and allows for evaluation immediately after. In more recent times, debridement using a machine producing sound waves has been used bedside to remove dead tissue. However, there is no evidence showing that it is more effective than a scalpel blade.

Surgical methods are another way to debride wounds. This is usually reserved for unusually large or chronic wounds that need deeper or more radical debridement. Instruments like the VersaJet combine manual debridement with highly pressurized water to remove non-viable tissue. The benefit of surgical debridement is that the patient is sedated so the doctor can be more aggressive and insure all dead is tissue removed. However, taking the patient to the operating room, needing medical clearance and the assistance of an anesthesiologist makes surgical debridement less practical and is only used if medically necessary.

Another type of debridement is use of ointments that contain enzymes that breakdown dead tissue. This is especially useful in situations where a patient has full sensation to the wound. Manual debridement may prove to be too painful for the patient to go through. In contrast, enzymatic ointments slowly dissolve making it painless for the patient. The downside of enzyme ointments is that they take longer to work. In addition, enzymes are very sensitive to small changes in pH, making it possible for them to be inactivated if the wound is too acidic or basic.

We’ll discuss mechanical debridement, autolytic debridement, as well as how wound care dressings can effect debridement in our next post.

Medical Maggots continued

As more and more patients have difficult wounds to heal, we have looked to the past and brought back more primitive yet effective ways to clean and close wounds. One of these techniques is putting maggots into wounds.

Maggots are simply baby or immature flies. There are many species of flies, some of which are not beneficial for wounds. So it is not a good idea to go diving into dumpsters trying to find a nice batch of them. Special pharmacies have them available for wound care clinics and hospitals. Once ordered, they can be shipped overnight and ready the next day for application.

Once the maggots are placed in a wound, precautions need to be taken so that they do not escape. A mesh net is put over the wound, and the wound is surrounded by a very adherent material. This keeps them in the wound so that they can deliver maximum benefit. The maggots will then secrete enzymes that dissolve the dead and non-viable tissue at the wound’s surface over a couple days’ time. Once dissolved, the maggots consume the components of the dissolved material. After a couple days in the wound, the maggots can become much larger then when they were put in. They are removed from the wound to assess if they did their job well. It may take a couple of treatments of maggot therapy to remove all the dead tissue.

Another great benefit of maggot therapy is that it can be combined with other wound treatments without caution. Antibiotics, hyperbaric oxygen, and even wound VACs (vacuum assisted closure) can be used after maggots to increase the chance of healing.

Although putting eventual flies into a wound may not seem very cutting edge or fancy, some treatments stand the test of time. Maggot therapy can help wounds to heal and prevent amputations of the foot and leg. Ask your podiatrist if he feels that maggot therapy may be beneficial for the healing of your wound.