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Education Material for Health Care Professionals: Book Version

THE FEET AND DIABETES

The prognosis for the second limb is poor in those who have had an amputation of the contra lateral limb.

SCREENING FOR DIABETIC FOOT PROBLEMS


A comprehensive foot exam assesses skin, circulation, and sensation. The test can be done during a routine clinic visit

Inspection

Inspection of the feet of the patient can be one of the most important aspects when screening for diabetic foot problems. In fact, the most important step in the prevention of foot problems is for the doctor to ask the patient to take off their footwear!

The presence of dry or excessively moist, skin, hair and nail abnormalities, corns, calluses, bunions, warts, foot deformities, heel spurs, flat arches, hammer toes, etc., are all pointers to an increased propensity for foot problems.  Occasionally, one may be surprised to find an injury or infections which the patient may have been completely unaware of.

The footwear should also be examined, not only to see if it is appropriate, but often one may find jutting nails which again the patient is unaware of due to the loss of sensations in the feet.

Sensation

After a detailed history which must include questions about numbness or tingling in the limbs, the most important aspect of grading diabetic neuropathy from foot ulceration point of view is to assess the degree of nerve involvement

The testing is usually done by testing if the patient can feel the pain of a pin prick or the touch of a cotton wool or the vibration of a tuning fork. These are perfectly useful and time honoured techniques. However, the problems with testing sensation with a pin prick, cotton wool or tuning fork is that every doctor does it in a slightly different way. It is very difficult to standardize the procedures and the results. To overcome these problems, two other methods are often used :

In recent times, it is felt as much information can be obtained by the use of the monofilament test. Consequently, biothesiometry is rarely carried, or even required, in the vast majority of cases.

A standardized filament is pressed against part of the foot. When the filament bends, its tip is exerting a pressure of 10 grams (therefore this monofilament is often referred to as the 10gram monofilament). If the patient cannot feel the monofilament at certain specified sites on the foot, he/she has lost enough sensation to be at risk of developing a neuropathic ulcer. The monofilament has the advantage of being cheaper than a biothesiometer, but to get results which can be compared to others, the monofilament needs to be calibrated to make sure it is exerting a force of 10 grams.


Sensation threshold screening using a 10 gram monofilament
(also known as Semmes-Weinstein monofilament).
  1. Use the 10g monofilament to test sensation.
  2. Show the patient the filament and touch it to his or her hand to show it does not hurt.
  3. The sites to be tested are indicated on the foot diagram below.
  4. Apply the filament perpendicular to the skin’s surface ( see Diagram A).
  5. The approach, skin contact and departure of the monofilament should be approximately 1.5 seconds duration.
  6. Apply sufficient force to allow the filament to bend ( see Diagram B).
  7. Tell the patient to say if he or she feels the filament. Do NOT ask “Do you feel this?”
  8. Do not allow the filament to slide across the skin or make repetitive contact at the test site.
  9. Touch the parts of the feet randomly.
  10. If the patient does not say “YES” at any point, go to another place and come back to this part again later.
Do not apply to an ulcer site, callous , scar or necrotic tissue


 Diagram A  
Diagram B  
The circles represent the places on the foot to test with the monofilament  
Consider  feet to be “at risk” if patient cannot feel the 10gm monofilament at any of the sites marked.  


If necessary, the following tests should be considered :
    1. Nerve Conduction, and
    2.  EMG studies.

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