• More than 75% of diabetic ulcers appear on the toes or plantar surface of the metatarsal heads. The remaining ulcers usually occur on the heel, plantar midfoot, or at sites of previous amputation.
In addition to ulceration, complications to the diabetic foot include Charcot arthropathy and infection.
Most important contributing factor is neuropathy – test with Semmes-Weinstein monofilament test.
The Monofilament Test
Performing the Test:
Patient should be lying supine with eyes closed
Touch the monofilament to the patient’s forehead or sternum so the sensation is understood
The monofilament should be applied perpendicularly to the skin with enough force to buckle it for approximately 1 second
Patient should respond “yes” each time he or she senses the monofilament
Foot should be tested at the dorsum of the great toe proximal to the nail bed, as well the planar surface of the foot and base of the fifth metatarsal.
Perform the stimulus in an arrhythmic manner so the patient does not anticipate when the stimulus will be applied
An abnormal result would be an inability to consistently identify the presence of the monofilament at any site
10g monofilament most commonly used
Perform a stimulus 4 times per foot. For each of the 8 stimuli, assign a score of 0 if not perceived, 0.5 if it is substantially less than that perceived on forehead or sternum, and 1 if it is perceived as normal.
A score of 3/8 or less means that the presence of neuropathy is likely
A score of 3.5 to 5 means the risk of new onset neuropathy in the next four years is high
A score of 5.5 or greater indicates there is a low risk of neuropathy in the next four years
Today, diabetes is the leading cause of Charcot joint. This refers to degenerative changes and destruction that follows repetitive trauma to insensitive neuropathic joints.
Characteristically affects the foot, including the ankle, tarsometatarsal, and metatarsalphalangeal joints.
Ask about symptoms of Charcot feet
Difficulty putting on shoes
Look for signs of Charcot joint
Anesthetic or hypesthetic feet
Soft tissue swelling (acutely, typically presents at ankle and midfoot with marked rubor/warmth)
Abnormal callus formation
Abnormal projections on the plantar arch “rocker sole”
In diabetics with foot ulceration and underlying radiographic abnormalities of the bone, it is very difficult to distinguish Charcot foot from osteomyelitis.
If ulceration present, test for osteomyelitis with the “probe test”
Gently probe the ulcer base with sterile blunt stainless steel eye probe
Three findings increase the probability of underlying osteomyelitis
Ulcer depth of more than 3mm of exposed bone (+LR 3.9)
Bickley L, Szilagyi P. BATES’ Guide to Physical Examination and History Taking. 9th edition. Lipincott Williams & Wilkins; 2007.
McGee, S. Evidence Based Physical Diagnosis. St. Louis Missouri. Saunders Elsevier. 2007.
Canadian Diabetes Association Clinical Practice Guidelines Expert Committee. Canadian Diabetes Association 2008 clinical practice guidelines for the prevention and management of diabetes in Canada. Can J Diabetes. 2008; 32(suppl 1): S1-S201.
Gardner D, Shoback D. Greenspan’s Basic & Clinical Endocrinology. 8th Edition. USA. McGraw-Hill. 2007.