- First apply the monofilament on the patient’s hands (or elbow or forehead) to demonstrate what the sensation feels like.
- Test three different sites on both feet, selecting from those shown in Figure 4.
- Ensure the patient cannot see whether or where the examiner applies the filament.
- Apply the monofilament perpendicular to the skin surface (Figure 5a) with sufficient force to cause the filament to bend or buckle (Figure 5b).
- The total duration of the approach -> skin contact -> and removal of the filament should be approximately 2 seconds.
- Do not apply the filament directly on an ulcer, callus, scar or necrotic tissue.
- Do not allow the filament to slide across the skin or make repetitive contact at the test site.
- Press the filament to the skin and ask the patient whether they feel the pressure applied (‘yes’/’no’) and next where they feel the pressure (e.g., ‘ball of left foot’/’right heel).
- Repeat this application twice at the same site, but alternate this with at least one ‘mock’ application in which no filament is applied (a total of three questions per site).
- Protective sensation is: present at each site if the patient correctly answers on two out of three applications; absent with two out of three incorrect answers.
- Encourage the patients during testing by giving positive feedback.
Monofilaments tend to lose buckling force temporarily after being used several times on the same day, or permanently after long duration use. Depending on the type of monofilament, we suggest not using the monofilament for the next 24 hours after assessing 10-15 patients and replacing it after using it on 70-90 patients. Sites that should be tested for loss of protective sensation with the 10g Semmes-Weinstein monofilament
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