Some people with diabetes lose their perception of feeling in their feet. This is called Diabetic Peripheral Neuropathy (DPN) and is defined as
“the presence of symptoms and/or signs of peripheral nerve dysfunction in people with diabetes after exclusion of other causes” (Bolton 1998).
Many people will be unaware that any such problems exist and up to 50 % of people at diagnosis may present with some signs of neurological changes.
DPN can lead to various problems.
- Lose of protective sensation resulting in the inability to feel pain
- Change of shape of the foot such as clawing of the toes resulting in areas of increased pressure which may cause areas of callus especially under the metatarsal heads.
The simplest and most evidence based way to determine if a patient is suffering from DPN is to test them with a 10g monofilament.
- Sensory examination should be carried out in a quiet and relaxed setting. First apply the monofilament on the patient’s hands (or elbow or forehead) so that he or she knows what to expect.
- The patient must not be able to see whether or where the examiner applies the monofilament. There are three sites to be tested on both feet are indicated. The 1st and 5th metatarsal heads and the plantar surface of the distal hallux.
- Apply the monofilament perpendicular to the skin surface.
- Apply sufficient force to cause the filament to bend or buckle.
- The total duration of the approach – skin contact and removal of the filament – should be approximately 2 seconds.
- Apply the filament along the perimeter of, not on, an ulcer site, 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 (‘left foot’/’right foot’).
- Repeat this application twice at the same site, but alternate this with at least one ‘mock’ application in which no filament is applied (total three questions per site).
- Protective sensation is present at each site if the patient correctly answers two out of three applications.
- Protective sensation is absent with two out of three incorrect answers – the patient is then considered to be at risk of ulceration.
- Encourage the patients during testing by giving positive feedback.
- The healthcare provider should be aware of the possible loss of buckling force of the monofilament if used for too long a period of time.
(Taken from the prevention and management of foot problems in diabetes: a summary guidance for daily practice 2015, based on the IWGDF Guidance documents)
Can you locate the posterior tibial pulse?
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Can you locate the dorsalis pedis?
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Diabetes is a condition that can affect the vascular system. The screening of somebody’s feet for signs of vascular insufficiency is a simple process and is carried out by palpating the two main pulses in the foot the dorsalis pedis and posterior tibial. If you can palpate either of these pulses on each foot then it is deemed the foot is sufficiently perfused vascularly and no further action needs to be taken apart from recording this. Some patient’s pulses are not easy to palpate even although their circulation is intact and this may be due to many factors i.e. the presence of swelling (oedema) or the fact that in up to 10% of the population the dorsalis pedis is not palpable. If the pulses are not palpable then the patient will need to have a more in depth vascular assessment to determine if there is a problem with their circulation. This assessment would generally be carried out by a specialist podiatrist who would take any appropriate action required.
The inability for somebody to self care or have help to self care can increase the risk of them developing a foot problem. The following factors may contribute to this situation:
- Visual impairment
- Inability to maintain personal hygiene
- Inability to check feet for any problems
- Learning difficulties
Previous ulceration is defined as an area that has previously been ulcerated but has subsequently healed. After ulceration the affected area never repairs itself completely and only returns to 70% of tensile strength. This area is always vulnerable to future ulcerations. Previous ulceration is the highest risk factor for future ulceration.
Active ulceration (pictures below) is defined by The International Working Group on the Diabetic Foot 2005 (IWGDF), as:
‘a full thickness wound, i.e. a wound penetrating through the dermis, below the ankle in a diabetic patient, irrespective of duration’.
NICE guideline [NG19]: Diabetic foot problems: prevention and management: 1.5 Diabetic foot ulcer recommend the SINBAD (site, ischaemia, neuropathy, bacterial infection, area and depth) or the TEXAS scale is used to classify a diabetic foot ulcer.
If during the screening process you discover the patient has a foot ulcer the patient should be referred without delay for treatment/management by an experienced podiatrist who is part of a multidisciplinary foot team/service.
Structural abnormality of the foot (pictures below) is defined as
‘A change in foot shape that resulted in a difficulty in fitting shoes which could be purchased in high street shops’. (Scottish Diabetes Group – Foot Action Group 2010).
A non significant structural abnormality of the foot can be described as a very minor change of shape of the foot which does not result in areas of pressure, leading to callus formation, and a difficulty in fitting shoes which could be purchased in high street shops.
Significant callus (pictures below) is defined as
‘Callus that requires Podiatric Management’ (Scottish Diabetes Group – Foot Action Group 2010).
Significant callus causes pressure on the underlying tissues which can result in the tissues breaking down and an ulcer developing. If a patient has significant callus and is not attending a podiatrist then they should be referred to have a treatment/management plan agreed and introduced to suit their needs.
Non significant callus can be described as callus that does not require podiatric treatment, does not pose any risk and can be treated/managed by the patient
The treatment of non significant callus or areas of dry skin can be managed by the patient after some simple instruction. The careful use of emery boards/ pumas stone, the regular application of a moisturiser cream and by following the advice given in the Low risk leaflet will usually achieve this.
To start the screening process you should:
- Seat patient on examination couch/chair
- Inform the patient that you are going to examine their feet to check their circulation, sensation and any other risk factors that they might have which could lead to a foot problem related to their diabetes
- Request patient remove shoes and socks/stockings and assist if required
Ascertain the following:
- Has the person with diabetes been experiencing any problems with their feet since their last screening appointment?
- Has the person with diabetes noticed any changes to their feet since their last screening appointment?
- Is the person with diabetes complaining or any podatric-type problems (e.g. corns, calluses, nail problems, etc…)?
- Does the person with diabetes attend a podiatrist regularly?