🩺 Diabetic Foot Examination

The diabetic foot examination is a specialized assessment designed to identify patients at risk of ulceration, amputation, and Charcot neuroarthropathy. It integrates components of vascular, neurological, and musculoskeletal examinations. By identifying loss of sensation and impaired perfusion early, clinicians can implement preventative strategies such as podiatry care and specialist footwear. Systematic annual screening is a cornerstone of diabetic care in the UK, significantly reducing the morbidity associated with the diabetic foot.

This examination is mandatory for all patients with Type 1 or Type 2 Diabetes Mellitus at least annually as part of their comprehensive diabetic review. It is also indicated whenever a diabetic patient presents with foot pain, a new lesion, swelling, or changes in skin colour. Any diabetic patient with a known history of peripheral vascular disease or peripheral neuropathy requires more frequent assessments. Evaluation is urgent if there are signs of infection (redness, warmth, pus) or if the patient reports a 'change in foot shape,' suggesting potential Charcot neuroarthropathy.

There are no absolute contraindications to a diabetic foot examination. However, in the presence of active, severe infection (e.g., wet gangrene or spreading cellulitis), palpation and mechanical testing should be performed with extreme gentleness to avoid pain and systemic spread of bacteria. Monofilament testing should not be performed on areas of heavily calloused skin, as this will give a false-negative result for sensation. If a patient has a suspected acute Charcot joint, weight-bearing should be minimised immediately, and the examination should focus on non-weight-bearing assessment to prevent further joint collapse.

The primary tool is a 10g Semmes-Weinstein monofilament for assessing protective sensation. A 128Hz tuning fork is used to test vibration perception, which is often the first sensory modality lost in diabetic neuropathy. A Doppler ultrasound probe may be required if peripheral pulses are difficult to palpate. General equipment includes a thermometer (or use of the back of the hand) to check for temperature discrepancies, and a torch to inspect between the toes. Gloves and basic dressing packs should be available if an active ulcer is present. Footwear should also be considered a 'piece of equipment' to be inspected.

Start by inspecting the footwear for wear patterns. Inspect the skin for colour, dryness, callus, and ulcers (look between toes and at the heels). Observe for deformities like bunions, hammer toes, or Charcot collapse. Palpate the temperature of the feet and the pedal pulses (Dorsalis Pedis and Posterior Tibial). Perform sensory testing using the 10g monofilament at 10 standard sites (including the plantar surface of the big toe and metatarsal heads). Test vibration sense at the hallux. Assess the ankle reflex. If an ulcer is present, document its location, size, and look for signs of infection. Finally, assess the patient's gait and ability to transfer if applicable.

Interpretation classifies the foot as 'Low', 'Moderate', or 'High Risk' based on NICE guidelines. The loss of protective sensation (unable to feel the 10g monofilament at 2 or more sites) and the absence of pedal pulses are the primary indicators of a 'high-risk' foot. Skin changes like dryness or hair loss suggest autonomic neuropathy or ischaemia. High-pressure areas indicated by callus formation are precursors to ulceration. A 'hot, red, swollen' foot in the presence of neuropathy is Charcot's neuroarthropathy until proven otherwise. Identification of an ulcer requires assessment of its depth, size, and signs of infection (e.g., Probe-to-Bone test).

The most frequent error is failing to inspect the 'interdigital spaces' (between the toes), where fungal infections and hidden ulcers often begin. Students frequently forget to check the footwear for foreign objects or high-pressure areas. Another common mistake is improper use of the 10g monofilament; it must be applied until it buckles to deliver the correct pressure, and the patient must not see when or where it is applied. Neglecting to palpate both the dorsalis pedis and posterior tibial pulses is common. Finally, many fail to assess for 'Charcot neuroarthropathy'—missing the signs of a hot, swollen, deformed foot in a patient with neuropathy.

Always ask the patient to remove their shoes and socks before you even begin the consultation. Use the 'Look, Feel, Move' approach but add 'Sensation' and 'Pulses'. When using the monofilament, always test it on the patient's arm first so they understand the sensation. Check the patient's socks for blood or exudate. Look for 'clawing' of the toes, which indicates motor neuropathy. If you find an ulcer, mention that you would perform a 'Probe-to-Bone' test to screen for osteomyelitis. Ensure you check the temperature of both feet simultaneously using the back of your hands to detect asymmetry.

Aligned with 'Diabetes Mellitus' and 'Vascular Surgery' topics. Students must know the NICE (NG19) risk stratification: Low (no risk factors), Moderate (one factor: e.g., deformity or neuropathy), High (previous ulcer, or two factors). Understanding the 'Diabetic Foot Triple Whammy'—Neuropathy (sensory, motor, autonomic), Ischaemia, and Infection—is essential. Knowledge of when to refer to the Multidisciplinary Foot Team (MDFT) is a common exam question, particularly the '24-hour rule' for new ulcers or suspected Charcot.