Eight Tests That Your Foot Doctor May Order

By Alex Kor, DPM, MS
Kaiser Permanente
Camp Springs Medical Center
Temple Hills, MD
January 2008

The New Year is upon us. Our country will elect a new President in 2008. The world will meet in Beijing in August to compete in the Olympic Games. Roger Federer may win 3 Grand Slam titles to surpass Pete’s record of 14. And, you, the Mid- Atlantic tennis enthusiast and player MAY sustain a foot and/ or ankle injury that will land you in the office of a health care provider. If so, you will benefit greatly from reading about 8 tests that may be ordered on your foot/ ankle condition.

# 1 - X-rays = All of us have had x-rays on some body part, but many of my tennis playing patients have been misinformed as to what information can be gained from an X-ray of an injured foot or ankle. X-rays do NOT show tendons, ligaments, nerves, cartilage or blood vessels. X-rays typically show bones and joints, and may, at times, show the absence of skin (e.g. infection). In addition, it is very important that every athlete appreciate that X-rays can be initially normal, and yet later it is discovered that a fracture of bone has indeed occurred.

#2 - Bone Scan = A bone scan is NOT as common a test. A radioisotope is injected into a patient’s arm, and the patient is subsequently scanned. If the patient’s x-rays are normal, and the bone scan is positive in the area of pain, there is a strong possibility of a fracture. In other words, a bone scan will “pick up” a fracture in situations when a fracture is suspected but the x-rays were normal.

#3 - MRI = A MRI or magnetic resonance imaging is becoming a very common test ordered on athletic injuries. It does offer the advantage of seeing soft tissue (e.g. tendons, ligaments, etc.) structures as well as boney abnormalities (e.g. bones, cartilage, joints, etc.). But, at times, it can provide too much information, and even “cloud” the picture. For example, if you are to drive an automobile from Maryland to California, you would request to know the major highways. These “major highways” are the x-rays and bone scans. On the other hand, if you were to take this same drive, you would not want to know every small street in every small town between Maryland and California. This scenario is similar to a MRI. Thus, I do not order MRIs on every foot and ankle injury, and typically reserve their use to difficult cases where the other tests have been of little to no help.

#4 – CT Scan = A CT Scan or CAT Scan or computed tomography is a test that is probably not ordered as much as it was 10 – 15 years ago. This test has the ability to look 3 dimensionally into a body part where the provider suspects a bone abnormality. In addition, in the foot, CT scans are excellent for detecting foreign bodies (e.g. wood, glass, etc.).

#5 – Ultrasound = Ultrasound uses high frequency sound waves to help in visualizing and thus diagnosing soft tissue conditions such as tendon tears, soft tissue masses, a strained arch, etc. This technology, originally developed for use in OBGYN, now is used in the office of podiatrists . It can, at times, avoid other more expensive tests.

#6 – Nerve Conduction tests = If an athlete is experiencing complaints that suggest a nerve problem (e.g. either within the foot or originating from the back), your podiatrist may order EMG / Nerve Conduction tests. Although, these tests can be quite painful, they are usually performed by a neurologist and attempt to detect the level of nerve involvement. In other words, a tennis player with a history of lower back pain, may complain of  intense, but vague foot pain of both feet. If all other tests are normal, one must make sure that the back condition is not causing or contributing to the foot problem.

#7 - ESR (SED RATE) = The ESR or Erythrocyte Sedimentation Rate is a simple, inexpensive, non–specific blood test that your foot doctor may order. By itself, this test does NOT diagnose a medical problem. But, the ESR is a number that, when very high (e.g. above 75), can strongly suggest a serious problem (e.g. a bone infection). On the other hand, if the ESR is normal (e.g. less than 20), the provider would be less likely to consider a serious problem in evaluating an athlete’s painful ankle/ foot.

#8 – D-dimer = The D-dimer is another blood test that is typically (only ordered) if a patient complains of sudden and intense lower leg/ calf pain. The typical patient that complains of such symptoms are usually over the age of 40, and may have other medical problems. The provider, ordering the blood test, is suspecting that the patient may have a blood clot. If this blood test is negative, there is absolutely NO chance of a blood clot. If the D-dimer is positive, the patient needs to be advised that he/she may have a blood clot and another test (e.g. Venous Doppler) needs to be ordered.

Obviously, I hope that all of you avoid the “injury bug” during the upcoming tennis season. But, if you are not that fortunate and have an injury, you will now be better informed when you are examined. Good luck!

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