Diabetic Foot Assessment


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A brief outline of a podiatric foot assessment

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  • Diabetes is now recognized as a chronic, debilitating and costly disease, predicted to double to 366 million by 2030. Something like, 47% of diabetics have some peripheral neuropathy and at a conservative estimate, 7.5% are suffering symptoms at the time of diagnosis. Research confirms early detection of the insensate limb is critical, but difficult because diabetic peripheral neuropathy (DPN) is often asymptomatic.Despite clear and authoritative clinical guidelines research also supports first-line providers do not screen enough and their care quality suffers as a result. The purpose of this short presentation is to highlight the podiatrist‘s role in screening the diabetic foot. (102)
  • I am a firm believer the great maker, (whoever she was), was a podiatrist, or at least a friend of podiatry, for the longer we live the more we seem to rely on the services of others to tend to our feet. All the more critical as the bludgeoning diabetic population becomes endemic among the 45 plus age group. (59)
  • For my sins, I am a community based podiatrist with a demographic made up of seniors, who are often: sight challenged hypertensive, peripherally ischaemic, venous return compromised, obese with ankle oedema, on anticoagulants, and suffering all manner of arthritides. High percentage are diabetic (and often not taking their medication), with chronic foot problems that limit mobility. Of course there are co-morbidities which collectively make toe nail clipping marginally safer than swimming blindfold slowly through a school of man eating sharks. However I suppose someone has to do it. (88)
  • Aetiology of diabetic neuropathy is still poorly understood although glycation is probably a major factor. (The importance of glycaemia has been confirmed by studies showing incidence is greatly reduced by strict glycaemic control.) Resultant changes to vasculature also play an important part in causation of nerve damage. Disruption to neuronal integrity and failure to regenerate results in progressive neuropathy characteristically presenting in a distal–proximal direction (stocking distribution). Loss of protective sensation means people unwittingly can damage themselves. Delayed healing and propensity to infection mean small cuts and other abrasions have the potential to ulcerate. It is now recognized regular foot screening helps monitor and prevent serious complications in people coping with peripheral neuropathy and peripheral vascular disease. The clinical conundrum:Some patients present with acute sensory neuropathy i.e. severe polyneuropathic pain i.e. burning, hyperesthesiae, paresthesia, and dysesthesia [an unpleasant, abnormal sense of touch], but with minimal deficit. All prone to nocturnal exacerbation. Clinical examination is usually relatively normal, sometimes with allodynia on sensory testing; a normal motor exam, and occasionally reduced ankle reflexes.Others more commonly present with chronic sensorimotor neuropathy and have a complete insensate foot and no symptoms. This neurological deficit may only be discovered during a routine neurological foot examination. (205)  
  • Currently there is no gold standard for chair side assessment of Diabetic Peripheral Neuropathy (DPN). Conventional wisdom supports symptoms alone have relatively poor diagnostic accuracy hence a combination of signs and symptoms approach is considered more appropriate. Symptoms may be primarily sensory, motor or both. Simple composite examination scores are as accurate as complex examinations. Best evidence supports the use of the 10g monofilament combined with the modified Neuropathy Disability Score (NDS) to chart protective sensation and identify those most likely to progress to ulcerative stage. NDS is a score based on vibration perception, pin-prick sensation, temperature perception, and ankle (Achilles) reflexes. (102)
  • From the 80s, Semmes-Weinstein monofilament examination (SWME) has been used in testing protective sensation. Initially they were developed to assess neuropathy in Hansen’s disease. At a given pressure to the skin (10 grams) the nylon filament bends. The 5.07 (10g) filament is used to ascertain the level of protective sensation. With eyes closed three sites are tested i.e. the plantar aspects of the great toe, the third metatarsal, and fifth metatarsal (The Australian Diabetes Society). Research suggests people unable feel the monofilament have a 7.7-fold increase in ulceration risk. Monofilaments have high inter and intra examiner reliability and are generally considered effective, inexpensive and simple screening for ‘at risk’ feet.The half -life of a Semmes-Weinstein monofilament is approximately 100 patients. Filaments fatigue and bend too easily, giving false positives after testing about 10 patients. They must be rested for 24 hours before regaining their firmness. (146)
  • A modified Neuropathy Disability Score (NDS) has been shown to be the most reliable test for sensitivity and grading diabetic peripheral neuropathy. Combination of different examination scores gives better sensitivity and specificity. Diabetic peripheral neuropathy manifests with a wide variety of sensory, motor, and autonomic symptoms. Smaller fibres are often the first to be affected and with continued hyperglycemia, larger fibres follow. The smallest sensory nerves are responsible respectively for thermal/burning pain (0.2-1.5 mu); and sharp pain (1-5 mu). Pin Prick sensation is tested with neurological pins. Altered thermal thresholds such as lowered heat-pain thresholds are associated with early changes in distal nerve segments and can be tested with simple heat/cold tests. Bigger A-alpha (I) and A- beta (II) responsible for propioception (13 -20 mu), vibration and pressure (6 -12 mu). A loss of propioception may result in a positive Romberg’s sign. Vibration Perception threshold is tested using a 128Hz tuning fork or RydellSeiffer tuning fork. Vibration Perception thresholds have a strong co-relation with nerve conduction velocities and are a reliable indicator of “risk” for future ulceration across a wide range of ages and durations of diabetes. (Neurothesiometer or Biothesiometer). Deep tendon reflexes with neuropathy are commonly hypoactive or absent. The maximum NDS is 10, with a score of 6 or more being predictive of foot ulcer risk. (219)Neuropathy Disability Score (normal = 0 abnormal = 1)Vibration Perception Threshold (can distinquish vibration =0 etc)Temperature Perception on Dorsum of Foot hot/cold (can distinguish =0)Pin Prick sharp/blunt (can distinguish = 0) Achilles Reflex (present =0 with reinforcement =1 Absent =1)
  • Motor weakness is unusual, although small muscle wasting in the feet and also the hands may also be seen in more advanced cases. Motor problems include distal, proximal, or more focal weakness. Symptoms include weakness or atrophy of intrinsic foot muscles and associated foot deformities. Foot slapping and toe scuffing or frequent tripping may be reported. Proximal limb weakness include difficulty climbing up and down stairs, difficulty getting up from a seated or supine position, as well as falls due to the knees giving way. Strength testing - Examine for distal intrinsic extremity muscle atrophy, since weakness of small foot muscles may develop.Autonomic neuropathy may involve the cardiovascular, gastrointestinal, and genitourinary systems and the sweat glands (sudomotor). People with generalized autonomic neuropathies may report ataxia, gait instability, or near syncope/syncope. Sudomotor neuropathy may produce heat intolerance, heavy head, neck, and trunk sweating with anhidrosis of lower trunk and extremities. Signs might include warm dry skin (in the absence of peripheral vascular disease) and the presence of plantar callus under pressure-bearing areas. The “at-risk” foot for neuropathic ulceration might also have a high arch (pescavus) and clawing of the toes. However, it must be emphasized that all patients with DPN with or without obvious foot deformities must be considered as being at risk of neuropathic complications, such as Charcot’s neuroarthopathy or foot ulceration. (127)
  • Claudication can be a useful symptom, but peripheral arterial disease (PAD) is commonly asymptomatic. Palpation of foot pulses is however a good simple test to determine the presence of peripheral arterial disease. The ankle-brachial pressure index (ABPI or ABI), using Doppler ultrasound is a useful adjunct to assess foot perfusion. Results can however be falsely elevated in the presence of arterial calcification and in this event clinicians are using photoplethysmography the measure toe-brachial pressure index or toe pressures. In the ‘toe’ examination, if the flow is deemed adequate patients are managed medically, surgically, and mechanically with the foci to heal and prevent severe recurrence. If the blood supply is determined to be inadequate, the patient is prioritised for revascularisation or ‘flow’. Once an appropriate blood supply is established the patient is returned to ‘toe’ for preventive management. (137).
  • A Foot Deformity Score helps identify high risk areas where repetitive trauma can cause breakdown, progressive ulceration, and infection. Screening includes signs such as: abnormal bony prominences, subluxation of the metatso-phalangeal joints, lesser toe deformities due to small muscle wasting, PesPlanus or PesValgus, previous amputation, and Charcot’s neuroarthropathy. About half all amputees experience a subsequent amputation of the other limb. Morbidity rates for limb amputees are poor with a life expectance of approximate five-years.Dryness, tineapedis, cracks, onychomycoses, acute erythema and tenderness, and fluctuance under calluses. (89)
  • Inadequate footwear makes a significant contributory factor in causation of diabetic ulcers i.e. 35% -50% of cases. Shoes are made in standard sizes and feet are not symmetrical like shoes. Poorly fitting shoes cause sheer which may lead to secondary skin changes.When shoes fail to support feet, high intermittent pressure result which puts the insensate foot at risk. A significant number of people wear shoes that do not fit their feet and research continues to shown poorly fitting shoes are more prevalent in the demographic with diabetic foot wounds than in those without wounds with or without peripheral neuropathy. A routine foot assessment includes size, volume, suitability and wear marks of presenting footwear are reviewed and discussed with the patient. (121)
  • There are several systems to categorize risk with the best known the University of Texas Diabetic Foot Risk System (with 7 categories). For simplicity however the demographic can be divided into four main divisions: Low risk i.e. normal sensation and palpable pulses. Recommend an annual foot inspection with education. Intermediate risk i.e. neuropathy or absent pulses or foot deformity. Recommend 3 to 6 monthly reviews. High risk i.e. where two or more risk factors are present (neuropathy, peripheral arterial disease or foot deformity) and/or a previous history of foot ulcer/amputation have been recorded. Recommend 3 to 6 monthly reviews.Critical category Recommend GP/Hospital referral within 24 hours. Increased assessment frequency helps monitor rapidly-developing problems, such as ulcers, infections, gangrene, and Charcot’s neuroarthropathy. All of which need immediate intervention. Until adequately assessed all Aboriginal and Torres Strait Islander people with diabetes are considered to be at high risk of developing foot complications and therefore will require foot checks at every clinical encounter and active follow-up. (164)
  • The CARE approach has been accepted by many health care systems across the Western World. In Australia the Enhanced Primary Care Plan gives greater access to clients who are potentially at risk. Foot Health Education Programs promote daily self foot inspections with informed foot hygiene that minimize inadvertent self harm. Advice on appropriate foot gear and where to get it is combined with and open access in the case of emergency. (71)
  • Early detection of the insensate limb is critical and improved Quality Adjusted Life Years is achieved through regular foot screening and foot care; in conjunction with intensive glycaemic control. To this end effective care involves clear communications between patients and other health care professionals. I hope this presentation will convince you to use podiatry services to improve the quality of care to our diabetic population. (65)
  • Diabetic Foot Assessment

    1. 1. A brief outline of a simple foot assessment Cameron Kippen
    2. 2. The longer we live the more we seem to rely on the services of others to tend to our feet.
    3. 3.  Seniors,  Sight challenged  Hypertensive  Peripheral vascular disease  Varicosities  Water retention  Arthritides  Diabetes  Obesity  Other co-moribidity
    4. 4. Ischaemia Deformity Infection Ulceration Charcot’s neuroarthropathy
    5. 5. Assessing Diabetic Peripheral Neuropathy • Monofilaments 5.07 (10g) • Neuropathy Disability Score • Vibration Perception • Pin Prick Sensation • Temperature Sensation • Propriception • Ankle Reflex
    6. 6. Vibration Perception Threshold Pin prick test Proprioception Achilles Tendon Reflex
    7. 7. Muscle Wastage Joint Mobility
    8. 8.  Pulses  Diagnostic Ultrasound  Ankle Brachial Pressure Index  Toe Index.
    9. 9.  Symmetry  Pivot points and Pressure areas  Amputation  Muscle wastage  Abnormal gait patterns
    10. 10.  Size (length and breadth)  Volume  Suitability  Wear marks
    11. 11.  Low risk i.e. no risk factors with palpable pulses and normal sensation. Recommend annual foot examination and education.  Intermediate risk i.e. the presence of neuropathy or absent pulses or foot deformity . Recommend review every 3 to 6 months.  High risk i.e. where two or more risk factors are present (neuropathy, peripheral arterial disease or foot deformity or a previous history of foot ulceration . Recommend 3 to 6 months reviews.  Critical risk Referral GP/Hospital within 24 hours
    12. 12.  Control Blood Glucose Levels  Annual Foot Screening Examination  Report change immediately  Engage in simple daily foot care
    13. 13.  Team Care Arrangements –item 723  General Management Plan – 721  Enhanced Primary Care Plan  Community Aids and Equipment Program (CAEP)
    14. 14.  National Evidence-Based Guideline Prevention, Identification and Management of Foot Complications in Diabetes April 2011 http://www.nhmrc.gov.au/_files_nhmrc/public ations/attachments/diabetes_foot_full_guideli ne_23062011.pdf  Australasian Podiatry Council http://www.apodc.com.au/  Diabetes Australia http://www.diabetesaustralia.com.au/
    15. 15. WARNING This material has been copied and communicated to you by or on behalf of Cameron Kippen pursuant to Part VB of the Copyright Act 1968 (the Act). The material in this communication may be subject to copyright under the Act. Any further copying or communication of this material by you may be the subject of copyright protection under the Act. Do not remove this notice