Table 5.2-10. Tools for identification of the at-risk foot

Symptoms

Identifying tool

Description

Loss of protective sensation

Monofilament

Performed using 10-g (5.07 Semmens-Weinstein) monofilament. Inspect 8-10 anatomic sites and 4 plantar sites

Biothesiometer

Used to assess vibration perception thresholds. Reading >25 V has sensitivity of 83%, specificity of 63%, positive LR of 2.2, and negative LR of 0.27 for predicting foot ulceration over 4 years

Tuning fork

Performed using 128 Hz tuning fork. Abnormal response occurs when patient loses vibratory sensation while it is still perceived by examiner

Peripheral vascular disease

Clinical features

History of decreased walking speed, leg fatigue, claudication; assessment of pedal pulses

ABI (see Lower Extremity Peripheral Artery Disease)

>1.30

0.90-1.30

0.60-0.89

0.40-0.59

<0.40

Arterial calcification

Normal

Mild arterial obstruction

Moderate obstruction

Severe obstruction

Arterial oxygen supply

Transcutaneous oximetry >30 mm Hg correlates with high likelihood of wound healing

ABI, ankle-brachial index; LR, likelihood ratio.