Assessment of the Diabetic Foot
Early intervention is crucial so screen your patients for signs of diabetes. Patient education, and continual reinforcement, is vital.
Often confused, screening and assessment are two different processes:
Screening – this involves tests to discover if a patient is at risk of ulceration. If the patient is deemed to have a risk then they ought to be assessed.
Assessment – used once the patient has been identified as being at risk , assessment is when a clinician utilises a small battery of tests to assess the level of risk.
Once a risk category has been defined, then an appropriate level of advice and care ought to be provided to the patient.
Screening
Screening for ulcer risk ought to be easy, quick and provide useful information. May we suggest the following tests:
10g Retractable Monofilament
Palpation of foot pulses
Medical history
Using this simple system, the clinician ought to be able to decide how to classify the patients’ risk status
The Assessment
Vascular
Use your eyes. Look at the skin. Is it dry, cracked, are there heel fissures?
Is the skin warm or cold ?
What is the temperature gradient like? Skin temperature gauged by feeling leg, shin, ankle, top of foot with the back of the hand. Not ideal, but does give a very rough indication of blood supply.
Huntleigh Doppler – proven more reliable than palpation with fingers in assessing pulses. Studies have shown that practitioners feel their own pulse and not that of their patients in some 40% of cases.
A typical neuropathic foot is warm and has dry skin , often with prominent MTPJs.
Neuropathic
Peripheral neuropathy affects 30% of the UK diabetes population. It is also present in chronic alcoholis, leprosy, Gullian-Barre, hypothyroidism and vitamin B12 deficiency.
A neuropathic foot is 7 times more likely to ulcerate than a non- neuropathic diabetic foot.
Distal symmetrical polyneuropathy ( most common form of chronic neuropathy) is progressive, predominently sensory with very little motor involvement.
Peripheral neuropathy is more prevalent in Type II diabetes patients
The purpose of your assessment is to look for altered sensation. Kumar (1991) and Young (1994) in their papers concluded that loss of sensation can lead to ulceration.
Vibration – very often the first sensation to be affected. The large myelinated fibres are responsible for vibration sensation. Do not use a hard surface to strike the fork – use thenar eminence of the hand, or pinch fork ends with your finger & thumb. Demonstrate on your patients hand first, to ensure they know what it feels like. Make the patient close their eyes, or look away then test predetermined sites on the foot. Usually 1st toe, 1st MTPjoint, and 5th MTPjoint. Be aware that vibration perception decreases with age, even in the non diabetic foot.
Pressure – testing the large myelinated fibres This test is performed using the Bailey Retractable Monofilament 10g. If the patient is unable to feel the 10g monofilament , they are at risk from ulceration. Rith-Najaran (1992) found that patients unable to detect the 10g monofilament were 10x more likely to ulcerate than those patients who were able to sense the 10g monofilament. It is important to have an accurate filament, hence we present the Bailey Retractable Monofilament . Booth & Young (2000) found ours was accurate and repeatable. Suggested test sites 1st toe, 1st MTPJ (most common sites of ulceration), 3rd MTPJ, 5th MTPJ and 5th toe. This covers all three plantar nerves. Don’t test callus or open wounds.
Temperature differentiation – using TipTherm® ask the patient if they can tell the difference between one end and the other. You’re now testing small myelinated and unmyelinated fibres.
Neuropad – this device is a moisture sensitive plaster which changes colour in the presence of sweat. If there is no colour change, the patient is deemed to be suffering from autonomic neuropathy.
Ankle jerk test – this tests the reflex arc, as stimuli go to the anterior root horn of the spinal cord and back to the foot (brain not involved).
There is a downloadable version of the assessment information entitled “Assessment of the Diabetic Foot”