Use of 10g monofilament in diabetic foot assessment

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Hello All,
Does anyone have a standard for testing sites on the foot with this instrument? Colleagues, not all podiatrists I have to add, have varying opinions testing and I would like to produce a ( evidence based ) standard for use in my region. Can anyone help please?

 

http://www.diabeticfoot.org.uk/

The above site gives a diagram of the recommended sites of testing, hope this is what you are after.

 

Testing sites

I personally think that testing plantarly is pointless, and I realise it is the adopted standard. I am yet to hear an argument why we should test areas that are affected significantly by calluses (hence invalidating the results because of an individual's biomechanics).

I test only non-weightbearing areas and ensure I test all nerves.

Hence, lat. 5th toe, med 1st toe, lat 5th mTP, med 1st MTP, styloid, tub of navicular, med and lat malleolus.

I did a study (unpublished) a thousand years ago which (inflating my ego) showed these sites to be reliable and good indicators of neuropathy.

The normal arguments for testing plantarly is because this is the area of likely ulceration. Given the nerves travel elsewhere (non-plantarly) I choose to test these areas. I believe the job of the monofilament is to test nerve function not how thick your calluses are.

Matt

 

Hi Matt,
That sounds interesting and certainly makes sense.
Too often we tend to do things by rote and for me one of the big benefits of degree-level training is that we do question accepted examination techniques and procedures .
Not that you need to have a degree to do that of course, but exposure to plenty of well-sourced written material + research methods has to help!
Regards,
David

 

Not directly related to the first question, but this paper in JBJS:
4.5-Gram Monofilament Sensation Beneath Both First Metatarsal Heads Indicates Protective Foot Sensation in Diabetic Patients

Concluded that:

Certainly raises question about using the 10g on 10 or 3 sites when a 4.5g on one site may be enough

 

Use od 10g monofilament

I want to Thank you for your comments. I had read an abstract on the paper re testing with 4.5g instrument, and I, like Matt, have difficulty understanding the plantar tests. Matt, perhaps you may still have a copy of your study in your archives? I, for one, would be interested to read it.

I'd also like to say Thank You for setting up this Forum. I work in the north of Scotland and find arenas like this invaluable for discussion with colleagues internationally.

Regards,
Sandra

 

Monofilament paper

I have just amazed myself by throwing together an abbreviated version of my paper and put it up on a blog of mine.

http://www.podiatryreview.com

Have not read through closely so don't be suprised by strange little quirks but you will get the drift.

Matt

 

Below is an extract from my PG thesis of 8 years ago. And from what I remember the sites that are now currently used were those that were initially used in the Birke and Simms article on people with Leprosy. They felt the monofilament would be better than a sharpened pencil, but still cheap enough to use in the sub-continent. The 1,3,5 toes, 1,3,5 MTPJ, Med/Lat arch, heel and dorsum test points have been validated somewhat by the Kumar etal study

More recently the Semmes-Weinstein monofilament has gained favour as a simple quantitative measure of sensory neuropathy. Although developed in the 1960s it was not widely used on diabetic feet until the 1980s. (Weinstein, 1993; Birke and Sims, 1986; Kumar, Fernando et al., 1991). The nylon filament will bend at a given force and then apply a constant pressure on the skin surface. Different thickness filaments provide a different skin pressure allowing a cutaneous pressure perception threshold to be established (Levin, Pearsall and Ruderman, 1978).
Many studies have shown the monofilaments to have both inter and intra examiner reliability. They have established normal results for the foot, along with abnormal results that put the neuropathic foot at risk of ulceration. Mooney (1992) defines normal sensation of the plantar surface of the heel at 4.16 (1.4g) for men and 4.09 (1.2g) for women with lower normals of 3.97 (0.8g) for men and 3.86 (0.7g) for women in the forefoot. Spivak (1994) defined normal sensation for the foot at 0.07g and Birke and Sims (1986) used 4.17 (1g) as a normal baseline. These variations on normal appear to be due to different testing procedures, sample populations and instrument calibration (Weinstein, 1993).
Birke and Sims, (1986) in a study of 132 neuropathic foot ulcerations found that no subject was able to sense a monofilament smaller than 6.10 (75g). From this information they established the 5.07 (10g) filament as the level of protective sensation. Kumar, Fernando and colleagues (1991) confirmed this in a large screening of 182 subjects with diabetes. No person with a foot ulceration could feel the 5.07 (10g) filament, concluding that monofilaments are an effective, inexpensive and simple screening device in identifying the ‘at risk’ foot. Other studies have supported these findings (Stevens, Edmonds, Foster and Watkins, 1992; Olmos, Cataland et al., 1995).
Recently an improved device with a rounded tip has become available that provides pressure alone and reduced pain, being called the Weinstein Enhanced Sensory Test (Weinstein, 1993; Spivak, 1994). This device is calibrated for increased reliability between instruments, but as a general screening tool the Semmes-Weinstein monofilament set has been shown to be more than adequate.

References
Anonymous ‘Proceedings of a consensus development conference on standardized measures in diabetic neuropathy. Quantitative sensory testing. [Review]’ Neurology 42(9): 1829-31, 1992.
Birke, J. A. and Sims, D. S. ‘Plantar sensory threshold in the ulcerative foot’ Leprosy Review 57(3): 261-267, 1986.
Consensus Statement ‘Report and recommendations of the San Antonio conference on diabetic neuropathy.’ Diabetes 37(7): 1000-1004, 1988.
Kumar, S., Fernando, D. J. S., Veves, A., Knowles, M. J., and Boulton, A. J. M. ‘Semmes-Weinstein monofilaments: a simple, effective and inexpensive screening device for identifying diabetic patients at risk of foot ulceration’ Diabetes Research and Clinical Practice 13(1-2): 63-68, 1991.
Levin, S., Pearsall, G., and Ruderman, R. J. ‘Von Frey’s method of measuring pressure sensibility in the hand: An engineering analysis of the Weinstein-Semmes pressure aesthiometer.’ The Journal of Hand Surgery 3(3): 211-216, 1978.
Mooney, J. ‘Touch/pressure thresholds of the soles of the normal healthy adult foot’ Journal of British Podiatric Medicine 127-133, 1992.
Olmos, P. R., Cataland, S., O’Dorisio, T. M., Casey, C. A., Smead, W. L., and Simon, S. R. ‘The Semmes-Weinstein monofilament as a potential predictor of foot ulceration in patients with noninsulin-dependent diabetes.’ The American Journal of the Medical Sciences 309(2): 76-82, 1995.
Spivak, M. Weinstein enhanced sensory test and peripheral neuropathy Connecticut, Connecticut Bioinstruments Inc., 1994.
Stevens, M. J., Edmonds, M. E., Foster, A. V. M., and Watkins, P. J. ‘Selective neuropathy and preserved vascular responses in the diabetic Charcot foot’ Diabetologia 35(2): 148-154, 1992.
Weinstein, S. ‘Fifty years of somatosensory research’ Journal of Hand Therapy 6(1): 11-22, 1993.

 

(10 g) monofilament sites

dear matt & others, i'm at a loss, the studies conducted by boulton & others used the plantar sites so for these sites it is the (10 g) monofilament (and now the (4.5 g)??). Surely for other sites further studies are needed to establish the relevant pressure as a cut-off for "at risk" insensitivity.
thanks, mark conley

 

Hello all,

Pham and associates(2000) added to the work of previous authors. They used a 10g monofilament and concluded that clinical examination and a 5.07 (10g) SWF test are the two most sensitive tests in identifying patients at risk for foot ulceration.
They used the plantar aspect of the hallux to test, with the patient's eyes closed, but don't specify the number of applications to each site.

I wrote to WH van Houtum of the International Working Group on the Diabetic Foot (why re-invent the wheel!). The group had found no conclusive evidence as to how many sites,or which sites, to recommend. Which is probably why we're all having this discussion now.

Ref: Pham H, Armstrong DG, Harvey C, Harkless LB, Guirini JM, Veves A, Screening techniques to identify people at high risk for diabetic foot ulceration.Diabetes Care 2000;23:606-11.

Cheers
John

 

Please Please Please Remember WHY you are doing this. All the above posts are valid and we should question long standing historical treatments. But the whole point is to EDUCATE the patient. We can have the debate about the effectiveness of filament testing for years to come, we need to educate the patient to help them make the link between loss of pain sensation and increased likeklyhood of ulceration infection Charcot etc.

 

Just out of interest I work in the Barnsley area and currently the practice nurses carry out the routine diabetic foot screening. If they find any problems they pass on to the Podiatrist. Please could you let me know how the foot screening is carried out in your areas and how effective it is?

Thank you,

Robert.

 

We use a standard, mass-produced, disposable 5.07mm monofilament. It's use is based on the Carville approach, used at the Hansen's Disease (leprosy) Center. I have found that there is often much discrepancy between providers of various levels who are doing LSU Foot Screenings. We have made attempts to standardize the screenings, educate the doctors, nurses, nurse practitioners who do the screenings. Once a patient "fails" the screening, they are referred to us. Our system, an amputation prevention clinic, includes me, an endocrinologist, vascular surgeon, orthopedic surgeon, infectious disease physician, nephrologist, nutritionist, and diabetes educator. What we have found is that most patients with lack of protective sensation also have other co-morbidities.
I'll try to post a link to the LSU forms that are used- hope this is helpful.


www.medschool.lsuhsc.edu/dfp/FootScreen.doc

 

Thank you for reafirming that the multi disiplinary team works the best, now if we can just get the bean counters to realise that prevetion is better than cure!

Does your team include an orthotist for bespoke footwear?

Robert Ramsey

 

I would think in this case a cure for the diabetic condition might be the go.

 

Hi All,
The "Position Statement from the Australian Diabetes Society" recommends two testing sites using the 10g monofilament: plantar aspect of 1st and 5th MPJ.
http://www.diabetessociety.com.au/downloads/positionstatements/limb.pdf

McGill et al evaluated the effects of different testing sites and buckling strengths on the sensitivity and specificity of using the Semmes-Weinstein monofilament to detect patients with insensate foot. They found using a combination of 1st and 5th plantar MPJ sites gives a reasonable compromise for time, sensitivity, and specificity.
http://care.diabetesjournals.org/content/22/4/598.full.pdf

So this is currently what I use in private practice as do some multidisciplinary High Risk Foot Cinics that I know of.
I hope this helps.

 

Reliability and Responsiveness of an 18 Site, 10-g Monofilament Examination for Assessment of Protective Foot Sensation.
Young D, Schuerman S, Flynn K, Hartig K, Moss D, Altenburger B.
J Geriatr Phys Ther. 2011 Apr-Jun;34(2):95-8.

 

As an undergraduate on placement when discussing this same issue with my mentor we got the brand new replacement 10g monofilaments out of their packaging and tested them on a scale (Post office calibrated scale), not one of them measured 10g of pressure, they varied from just above 6 to 9.3. From memory I think we tested 16. We then got the in-use monofilaments from the 4 other clinics, totalling 9 in all and on testing them found that they were unable to provide 10g of pressure either. So how accurate are they, new or old in establishing neuropathy?

 

The purpose of this research is to highlight the need for more research!! QED. Again it tends to highlight my point about educating the bit at the other end, normally pain protects, no pain no protection. Or the worst and most common scenario limited feeling in some areas with loss of sensation under areas such as under the 1st MPJt leading to overloading and ulceration.
In answer to your question how accurate are they, they are one tool in our box of tricks and as ever the patient as a whole should be considered and not just the result from one test.

 

As a rule I perform 3 assessments in regards to assessing for neuro changes, or simply establishing a base line for each client on intial assessment (ie: what they respond like today verses 12 months time, verses 5 years time).
1. 10 gram monofilament.
2. 128 hz Tuning fork
3. Ankle Jerk reflex.
Don't assume that if you get a response in all places with the 10 gram monofilament, that there are not neuro changes present. Sometimes they may be fine with 10 gram monofilament, and indicate no response to Tuning FOrk.
At the end of the day, if you don't establish some form of baseline, then you will never know if the client has changes later on down the track. Research supports the use of 10g monofilament testing (even if it is a little off at times!).

Hope this helps.

 

I use a monofilament myself, in my surgery, and make sure that I TEst my patients, on an annually basis.

If there are any differences between one year and the other,then I would write and report this to their dr, obviously, with their approval !

Although,the Test is definately not infinitive, it is a basis, to connect with your patient. and for your patient, to realise, that he or she, is being looked after,both by the "Pod"that they are paying.and also the nurse and dr, that is also looking after them !

We are known as professionals, to "Spot" things first, before any nurse or dr, due to the fact, that we see the patient more oftern than the H.P !

The patient is our Number One Fan, remember, so it is important that they know that we are looking after their every need !

that in the long run, makes sure that the patient returns to our surgeries, as that is the only way, we will keep our practice up and running !

Caroline

 

I too use the 10gm monofilament with patients on a yearly basis, but have been concerned about the possible inaccuracy of the tool. So I read Jacquie's post with particular interest and concern! Are monofilaments calibrated by the manufacturers? Obviously such variation as listed above is a serious problem regarding diagnosis of peripheral neuropathy.
:bash:

 

Quick straw poll; Do you ask your patients what they know about diabetes effects on their feet before comencing diabetic foot checks?
Vibration can also be a bit of a red herring as it naturally decreases with age and also can be effected by HAV surgery.

 

I always ask patients what they know about Diabetic foot health and fill in any blanks for them. Agreed about vibration sensation, I use it but treat results cautiously due to age variations.

 

I too use the ankle reflex,vibration perception and the 5.07N monofilament on 10 sites as per the NHRMC 2011 guidelines.If there are signs on PN I then check temperature and sharp/blunt. What confuses me is that the NHRMC 2011 guidelines have a neuropathy disability score with a maximum of 10 points , but unlike the deformity score [minimum of 3/6 criteria and you have deformity as a risk factor] there is no scoring out of 10 for PN.Does any one know how it scores?
Cheers,
Jo

 

About 10 years ago, i took two 5.07 monofilaments to the pathology lab (Canberra Hospital, not small) and amazingly, to me, they were very close to 10 g weight when they started to bend, can't remember exactly but within 0.5 g