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MARCH 2006 • PODIATRY MANAGEMENTwww.podiatrym.com 253

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Continuing

Medical Education

A look at the primary reasons why diabetic ulcers don’t heal.

Goals/Objectives

1) To understand thethree mechanisms of ulceretiology.

2) To better assess therole limited joint mobilityplays in the biomechanicsof the diabetic foot.

3) To understand the roleof plantar pressure, pres-sure/time and repetitiveloading.

4) To better evaluate andselect an off-loading devicefor patients and under-stand their advantages anddisadvantages.

tion are performed on patientswith diabetes, most of which areprecipitated by a foot ulcer. Stud-ies have demonstrated that mostfoot ulcers are caused by a combi-

Continued on page 254Plantar neuropathic diabetic

foot ulcers are a leadingcause of amputation on in

the United States. Fourteen to

By Vincent Giacalone, DPM twenty percent of patients withfoot ulcers require an amputation,contributing to the $6 billion an-nual cost of amputations in theU.S. alone. Each year greater than82,000 lower extremity amputa-

Off-Loadingthe Diabetic

Foot

Off-Loadingthe Diabetic

Foot

D I A B E T I C F O O TD I A B E T I C F O O T

also the mechanism which causesheel and sacral decubiti. In theneuropathic patient, the pain re-sulting from the local ischemicprocess is not acted upon and thepressure continues.

The second mechanism is thatof high pressure over a short peri-od of time, such as stepping on asharp object. The third mecha-nism - by far the most commoncause of plantar ulcerations – ismoderate repetitive pressure, nothigh pressure, not low pressure,but rather somelevel of pressurein-between whichis repeated witheach step.

The thirdmechanism de-serves a greateramount of discus-sion and detail .Typically, patientswith diabetes develop sensory, au-tonomic and motor neuropathytogether. Motor neuropathy leadsto clawing of the digits whichplaces a reverse buckling effect onthe MPJ’s. As the digits becomedorsally dislocated on themetatarsal heads, a plantar force isplaced on the metatarsal heads,increasing vertical pressure.

In addition, the digits con-tract, causing an anterior migra-tion of the plantar fat pad distallyinto the sulcus. This leaves the

plantar MPJ’swithout fat padpressure attenua-tion, and onlyplantar skin. Acombination ofu n p r o t e c t e dplantar skin (dueto loss of the fatpad), increasedp l a n t a r - f o r c efrom the digitsmigrating on thedorsal MPJ’s andperipheral senso-ry neuropathy,creates a nega-

tive scenario. Each step a patienttakes results in some degree of tis-sue damage, depending on theamount of pressure. As the tissueis damaged with each progressivestep, the lack of pain perceptionallows the patient to continue

walking without guarding, untileventually the tissue breaks downand an ulceration develops.

How Much Pressure is TooMuch?

Studies demonstrate that theaverage patient takes approxi-mately 15,000 steps per day. Manystudies have highlighted a“threshold” for plantar pressure,from 500 kilopascals (kPa) to900kPa using a variety of comput-erized gait and plantar pressure

analysis systems.This, however,can provide a con-fusing picture. Asan example, pa-tient A places400kPa sub 2ndMPJ and walks6000 steps perday, and developsan ulcer. Patient B

places 900kPa sub 2nd MPJ, how-ever, only takes 2,000 steps perday, and does not develop anulcer. Even though patient A hada lower pressure, he took moresteps. So we know that it’s notonly pressure that causes plantarulcers in the neuropathic patient.It’s also the number of load cyclesor amount of steps a patient isplacing on the area.

In addition to plantar pressureand number of load cycles, an ad-ditional factor is what is known asthe pressure time integral, theamount of time spent on a partic-ular area during the gait cycle. Fora variety of reasons, includinglimited joint mobility, foot struc-ture, foot type and rigidity, as wellas Achilles tendon contracture,many patients with long-standingdiabetes will have an increasedpressure-time integral. Duckworthand others have noted significant-ly higher pressure time integralsfor patients with neuropathy andplantar ulcers compared to diabet-ic controls and those with neu-ropathy without an ulcer.(16) Pa-tients spend more time during thegait cycle on the area of ulcera-tion, which is a primary contribut-ing factor in the ulcer formation,as well as a detriment to healing.Longitudinal studies have demon-strated that patients who demon-

Continued on page 255

254 www.podiatrym.comPODIATRY MANAGEMENT • MARCH 2006

Diabetic Foot...

nation of peripheral sensoryneuropathy and foot trauma,

either major or minor. Peripheralarterial disease is often a compli-cating factor and usually not amajor causative factor.

The goal of the podiatrist treat-ing a patient with a plantar footulcer is to heal the wound asquickly as possible without com-plication. There are four majorreasons that plantar ulcers fail toheal:

1. Peripheral arterial disease re-sulting in poor wound perfusion.

2. Infection, in the form ofcritical wound bacterial contami-nation and colonization, acutesoft tissue infection and/or under-lying osteomyelitis.

3. Faulty wound healing, con-sisting of growth factor deficiency,abnormal matrix metaloproteasesfunction or metabolic and nutri-tional abnormalities.

4. Pressure applied directly tothe wound in the form of ground-reactive and weight-bearingforces, both vertical and shear fric-tion. This is the greatest detrimentto wound healing.

Three Etiology MechanismsThe late Dr. Paul Brand was

the first to delineate the threemechanisms which are the etiolo-gies for plantar foot ulcers in aneuropathic pa-tient.(1) The firstis low pressuresustained for along period oftime. It takes sev-eral pounds persquare inch ofpressure toblanch humanskin. A patientwith il l- f ittingshoes will havepressure on bonyp r o m i n e n c e ssuch as the dor-sal interpha-langeal joints, lateral 5th metatar-sophalangeal joints (MPJ), or me-dial 1st MPJ. The shoe pressurewill blanch the tissue, resulting inlack of perfusion and local is-chemia, resulting in tissue break-down within several hours. This is

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There is no clearly documentedthreshold of plantarpressure for tissue

breakdown.

The greatest detriment to woundhealing is pressure

applied directly to thewound in the form of

ground-reactive and weight-bearingforces, both vertical and shear friction.


Testing for Plantar Pressure

The greatest problem withcomputerized plantar pressure gaittechnology is the fact that it is rel-atively expensive and not readily

available to most podiatric physi-cians in their daily clinical prac-tices. Many but not all areas ofhigh pressure, however, may beidentified by a simple clinical ex-amination and the presence ofplantar callus, as well as increasedskin temperature in the area atrisk. It is well understood that in-creased pressure results in in-

creased callus and/or temper-ature. The inverse is also truethat increased callus will re-sult in increased pressure. Asthe cycle continues the area ismore vulnerable to break-down. Several plantar pres-sure studies have demonstrat-ed pressure reductions be-tween 24 to 32% in callusareas once callus tissue wasdebrided.(20,28) Callused tissue,

strate increased time in the area ofhigher pressure are more likely todevelop an ulcer.

There is no clearly document-ed threshold of plantar pressurefor tissue breakdown. The reasonfor this is differences in individualfoot structure and function, plan-tar tissue thickness, pressure-timeintegrals, and number of load cy-cles for a particular patient. It isaccepted that the greater the plan-tar pressure the higher the risk ofbreakdown. Armstrong, et al . ,identified a pressure of 700 kPawith 70% sensitivity as the divid-ing line between high risk andlower risk of ulcer development.(12)

Patients below 700kPa were atlower risk, but not at no risk.Plantar pressure measurement, in-cluding peak pressure and pressuretime integrals, is a significant clin-ical tool for evaluating and screen-ing patients with diabetes in orderto evaluate those who might be athigher risk of ulcer development.In addition, this research will as-sist us in a more complete under-standing of diabetic foot function,as well as in the development ofappropriate foot gear.

Diabetic Foot... however, will not pro-vide information regard-ing pressure time or numberof load cycles.

A simple hand-held skin ther-mometer is an extremely usefultool for patients and clinicians todetermine areas of risk throughincreased skin temperatures. Pa-tients or physicians who evaluatethe skin temperatures at the plan-tar MPJ’s and identify an area ofsudden increase in temperaturecompared to adjacent areas or thesame site on the contra-lateralfoot can be alerted early as to po-tential breakdown. This informa-tion can then be used to have thepatient curtail weight-bearing ac-tivity until skin temperatures nor-malize.

The physician must obtain in-formation regarding the patient’sdaily activity level, shoe gear andoccupation. Additionally, a highquality pedometer worn by thepatient with neuropathy and ahigh risk foot will provide key in-formation. This information canalso be used to assist the patientin limiting his/her daily activityonce a certain pre-determineddaily number of load cycles orsteps are reached.

Limited Joint MobilityRegarding pressure and time,

there are several biomechanicalscenarios which will cause a high-er pressure time relationship, suchas the condition of limited jointmobility. Limited joint mobility(LJM), also known by the namecheiroarthropathy, is a non-enzy-matic glycosylation of the joint

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A simple hand-held skin

thermometer is anextremely useful tool

for patients andclinicians to determineareas of risk through

increased skintemperatures.


Photo #2: A typicalp o s t - o p e r a t i v eshoe flexing at theMPJ’s as the pa-tient goes throughpush-off, increas-ing plantar fore-foot pressure.Photo #1: A 62-year old patient with plantar

hallux ulcer secondary to peripheral neu-ropathy, and limited first MPJ dorsi-flexion,resulting in tissue breakdown from moder-ate repetitive pressure

for plantar forefoot ulcers. The pa-tients broke into two groups,those who healed in 45 days inthe TCC and those who failed toheal in the same time period.Those who healed had an ankledorsi-flexion of + 2 degrees. Thosewho did not heal had an averageankle joint dorsi-flexion of –10 de-

grees. These pa-tients then un-derwent a percu-taneus tendo-Achilles length-ening (TAL) fol-lowed by TCC,and 94% went onto healing within39 days. Thisstudy demon-strated the nega-tive force of high

plantar forefoot pressures due toankle joint equinus. Armstrong in1999 presented data which lookedat 10 patients with a history ofplantar forefoot ulcers and mea-sured their ankle joint dorsi-flex-ion and plantar pressure pre andpost-TAL. Pre-operatively, all 10had a dorsiflexion of 0 degreeswith a pressure of 860 kPa, andpost-TAL in-creased the anklejoint dorsiflexionto +9 degrees andlowered the fore-foot pressure to630 kPa.

Mueller, et al.,reported on mus-cle strength post-TAL.(14) He notedthat posteriorp l a n t a r f l e x o r ymuscle groupstrength was re-duced 32% post-TAL and returnedto pre-TALstrength within 7months. It can bepostulated thatpressure reduc-tion and ulcerhealing is due inpart to this reduc-tion in plantar-flexory power. Ofgreat concern, however, is thebiomechanical alteration which oc-curs with a TAL. We know thatover-lengthening of the Achillescan create a calcaneal gait, resulting

in difficult-to-heal plantar calcanealulcers.

In addition, due to increasedforces on the mid-foot, the risk ofa mid-foot Charcot is increased.We do need long-term studies tofollow the progression of TAL pa-tients, as well as algorithms toallow for more appropriate plan-ning of our surgical proceduresbased on foot type and structure,cavus vs. planus, etc. Differentfoot structures will function differ-ently regarding plantar pressureand loading.

Studies by Ledoux havedemonstrated what many wouldconsider the obvious: that patientswith diabetes and cavus feet willpresent with a greater tendencytowards prominent metatarsalheads, bony prominences andclaw toes, while planus feet withincreased talometatarsal angleshave increased lesser metatarsalpressure.(5)

Diabetes and PeripheralNeuropathy

We know very clearly that pa-tients with diabetes and peripher-al neuropathy are at a significant-

ly greater risk ofdeveloping footulcers. This isdue to multiplefactors, includingmotor neuro-pathic changesto the forefootleading to clawtoes, anterior mi-gration of theplantar fat padand retrogradeplantar pressureon the plantarmetatarsal heads.Patients withsub-hallux ulcer-ation have limit-ed joint mobilityat the first MPJ,resulting in in-creased plantarpressure. If youevaluate these

patients clinically, they appear tohave typical hallux limitus; how-ever, many times absent are theradiographic changes typicallyseen in patients with hallux limi-



Diabetic Foot...

structural proteins secondaryto elevations in blood glucose

levels. This glycosylation resultsin an irreversible cross-linking ofcollagen and keratin, causingthickening of skin, tendons, liga-ments and joint capsules, leadingto a reduction injoint flexibilityand a reductionof joint motion.This occurs mostnoticeably at theankle joint,where it affectsand reducesankle joint dorsi-f lexion duringgait, resulting inhigher plantarforefoot pressures, as well as alonger pressuretime integral.This also affects the subtalar joint,limiting pronatory shock absorp-tion. When LJM occurs at the firstMPJ, it results in higher sub-hal-lux pressure.

The incidence of LJM varieswidely from 8-42% of those withtype I diabetes to 4–76% of thosewith type II. Greater than 66% ofpatients with diabetes of morethan 5 years have some degree ofLJM. This limitation is associatedwith higher plantar forefoot pres-sures, greater incidence of ulcera-tion and reduced ankle jointdorsi-flexion. In 1991, Fernandofound significantly higher peakplantar pressures in those withLJM with peripheral neuropathy(PN) compared to those withoutLJM.(19) Diabetic foot ulcers werenoted in 65% of those with LJMand PN compared to only 5% inthose with PN without LJM. Afterscreening 1,666 patients in anout-patient diabetes clinic, Laveryin 2002 found that 10% of all pa-tients demonstrated equinus atthe ankle joint.(21) He also notedthat patients with equinus had athree times greater risk of higherplantar pressures.

Ankle Equinus and LJMA study by Lin highlights the

effects of ankle equinus and LJMon plantar forefoot ulcer heal-ing.(22) Linn treated 93 patientswith total contact casting (TCC)

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Patients with sub-hallux ulceration

have limited jointmobility at the first MPJ,

resulting in increasedplantar pressure.

The post-op shoecertainly has its

advantages in that it is inexpensive, easilymodified and available

in various sizes, but it provides for no

biomechanical support, allows for

shear forces to take place, and

there are significantfitting and

slippage problems.


with adhesive and a secondarydressing. The patient wears a rigidsole post-operative shoe, and thedressing is changed at least week-ly. Of concern is the aperture orcut-out area, which may cause anedge effect at the ulcer’s periph-ery, and increase vertical andshear forces, impeding healing.They cannot be utilized in pa-tients with friable skin, dermato-logical disorders or adhesive aller-gies.

Fleishli & Lavery evaluatedside-by-side the off-loading poten-tial of the felted-foam dressingwith a variety of other modalities,including TCC’s, pneumatic long-leg walkers, half shoes, post-opshoes, and simple canvassneakers.(27) They found that thefelted-foam performed slightlybetter than the post-op shoe alone

in reducing plantar pressures,however not nearly as well as theTCC or long-leg walkers. In a 2003study by Zimny, et al., a felted-foam dressing was evaluatedagainst the use of a half shoe in 54patients in a prospective random-ized trial . (6) The felted-foamgroup’s healing rate was0.5mm/week vs. 0.4mm/week inthe half shoe group with a 75-dayhealing time vs. 85-day healingtime in the half shoe group. Com-pared to an average healing timeof 42 days in several studies onthe TCC, the felted-foam does notfare well.

Due to the fact that thepadding, in combination with apost-op shoe, does not lock theankle joint and prevent anklejoint plantar-flexion during push-off, its beneficial off-loading effectis limited. It does, however, havebenefits, such as in the patientwho will not accept a cast or walk-ing boot, or any other modality,

tus. The reason for this is LJM, orsoft tissue block or contracturerather than a bony block. Due tolack of 1st MPJ dorsi-flexion dur-ing gait, there is a significant in-crease in plantar hallux pressure.In addition, this causes the halluxto load early with an increase inthe pressure time integral. Thesepatients also have some level ofLJM occurring at the AJ and STJ.

The plantar skin is traumatizedwith increased plantar pressurethrough repetition in the face ofperipheral neuropathy, resultingin tissue breakdown and ulcera-tion. The key for all podiatric phy-sicians is to obtain complete ulcerhealing, without complication, inthe shortest period of time. Inorder to obtain this, three factorsmust be addressed. The woundmust be free of infection and highlevels of colonization and have alow bio-burden, the wound musthave adequate vascularity forhealing, and sufficient off-loadingmust be adhered to. It is oftensaid, “It’s not what you put on,it’s what you take off,” which isthe most important factor in heal-ing. We must select an off-loadingmethod which meets our objectivefor pressure reduction or elimina-tion, while working within the pa-tient’s limitations or parameters,as well as considering his or herrisk of falling.

Off-Loading DevicesSome of the most commonly-

used off-loading devices rangefrom bed rest—which is not onlyimpractical in many cases but isoften unhealthy for most of ourpatients—to wheelchair use, to de-vices such as post-op shoes, roll-abouts, pneumatic walkers, toTCC. There are pro’s and con’s foreach device.

Felted-Foam DressingsFelted-foam dressings were

popularized by the Deaconess pro-gram for the treatment of plantarulcers and are used by many cen-ters throughout the country. Theyconsist of a multi-layered feltedfoam dressing applied to the footwith a cut-out around the ulcerarea, and are fixed to the foot

Diabetic Foot... or in a patient whereanother device is simplytoo dangerous and poses ahigh fall risk. I personally usethe felted-foam concept with suc-cess on these types of patientswith the “something is better thannothing” philosophy. When prac-tical, I will often add a half shoeor long-leg walking boot to aug-ment the pressure reduction. Ad-ditionally, older patients with re-duced push-off forces during gaittend to gain greater benefit fromthe felted foam dressing.

Post-Op ShoesThe post-op shoe certainly has

its advantages in that it is inex-pensive, easily modified and avail-able in various sizes. The down-side, in my opinion, outweighsthe advantages. The shoe providesfor no biomechanical support, al-lows for shear forces to take place,and there are significant fittingand slippage problems. Addition-ally, compliance with these shoesis less than ideal, with most pa-tients admitting they do not wearthe shoe as directed. The greatestdeficit to healing plantar forefootulcers is that the outsole is flexibleand bends when the patient goesthrough the push-off phase ofgait. When the shoe bends duringgait, it concentrates and increasesthe pressure and focuses it underthe forefoot during push-off. Inorder for the shoe to become use-ful, you must create a rigid rollersole with the apex of the rockerbeginning just proximal to themetatarsal heads.

The Darco® diabetic shoe is ofsl ightly greater value, with amore, but not completely, rigidsole. Similarly, the DH® pressurerelief shoe, with removable hexag-onal plugs, has a pressure relief in-sole and works fairly well. Thegreatest disadvantage any shoe-type device has is its inability toprevent the ankle joint from plan-tar-flexing during gait. If the ankleis not locked and is allowed toplantar-flex during gait, the fore-foot loads, and pressure is in-creased. The DH shoe, however,does have a more rigid roller out-sole.

A rigid roller sole also limitsContinued on page 258

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The total contact cast remains

the gold standard for off-loading

a plantar diabetic foot ulcer.

elevated 4 cm., and has a narrowerbase of support, which can be verydifficult for older patients to am-bulate with. Gait lab evaluationshave demonstrated that the pres-sure reduction ability of this shoeare significant; however, this mustbe balanced with the patient’scompliance, comfort levels andstability, as well as fall risk.

Removable Long-Leg WalkingBoots

Removable long-leg walkingboots have several distinct advan-tages. They are removable forwound inspection and greatersleeping comfort, reusable, cost-ef-fective, may provide for edemacontrol, have a built-in rigid rock-er sole, lock the ankle joint andlower plantar forefoot push-off,and are available in a variety ofsizes. There are several particularbrands which appear to providefor better control than others,such as the DH® walker, Air Cast®

walker, and the Bledsoe® diabeticconformer boot. These are avail-able in up to extra-large; however,you may have difficulty fitting apatient with a widened midfootCharcot foot.

The Bledsoe boot provides sev-eral advantages. One is the factthat it is available in particularsizes, such as men’s or women’s,8-9 or 10-11, etc., and specificallyleft and right, in order to obtain amore appropriate fit. Additionally,

the boot containsan auto-moldinginsole base, as wellas a liner, to allowfor a total contactinsole. This wil lprovide for pres-sure uptake in thearch and heel area,l imit rear-footmovement andshear forces, andallow for greater re-duction in forefootpressure and shear.

Patient con-cerns with thewalking boots arethe fact that theyare relatively heavyand hot, somewhatdifficult to walk in,and may require a

contra-lateral shoe to provide forgreater balance.

Total Contact CastThere is no question that the

total contact cast remains the goldstandard for off-loading a plantardiabetic foot ulcer. In physics welearn that Pressure =force/area.(p=f/a). The mechanismfor the TCC’s effectiveness is the

fact that the pressure is reducedbecause the same amount of forceis distributed over a much largerarea, P = f / a. Additionally, thecast is very effective at edema con-trol and most importantly, lock-ing the ankle and completely pre-venting ankle plantar flexion andforefoot push-off. The TCC alsoforces patients’ compliance asthey cannot remove it. It also de-creases cadence and shortens pa-tients’ stride length, and elimi-nates shear forces.

I am often asked about the ef-fects to the contra-lateral foot. In-terestingly enough, studies look-ing at this have demonstrated thatmost patients have pressure reduc-tion on the contra-lateral foot, aswell. The reason is the shortenedstride length and decreased ca-dence. By adding a cane for thecontra-lateral side, you can furtherreduce pressure on the contra-lat-eral side, as well as improve pa-tient stabil ity and comfort. Astudy by Drerup demonstrated apeak plantar pressure reduction of14.5% when stride length was re-duced by only 23%.(4)

The disadvantage to the TCC isthat it has a steep learning curvefor the physician. It requires a sig-nificant amount of experience forlearning how to apply and removeit, and requires frequent removalsand reapplications. Is costly due



Diabetic Foot...

dorsi-flexion of the halluxand toes, and therefore the in-

volvement of the forefoot rockermechanism reduces forefoot pres-sure up to 30%, independent ofwalking speed. The Darco® Or-thowedge healing shoe allows forless forefoot pressure, with a 10degree dorsi-flexion angle; how-ever, the negative heel can andoften does result in Achilles ten-donitis and can be somewhatclumsy for many patients to wear.The integrated prosthetic & Or-thotic System (IPOS)® half shoealso has a negative heel, which is

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There are some plantar lesions, whichdespite the best andmost appropriate off-loading, simply

will not heal.

Photo #4: A patient begins to ambulate with the use ofa total contact cast.

Photo #3: The use of felted foamdressing for a plantar ulcer.


better than for the walkers. Thereason for this, most hypothesize,is the fact of forced compliancewith the TCC. Although the pres-sure reduction is similar with thewalker and the TCC, ulcers healfaster in the TCC simply becausepatients cannot remove it. Mostpatients are notas compliantwith the walkersand remove themat home.

In a study inDiabetes Care in2003, patientswith foot ulcerswere given awaist-worn pe-dometer andwere providedwith a CAMwalker with acomputerized pe-dometer imbedded, which was notaccessible to the patient.(7) Thestudy showed that patients loggedsignificantly more steps with thewalking boot off than on, usingthe cam walker only 28% of theday. A small subset of patients,only 30%, wore the device for60% of their activity. I have uti-lized the concept of the “InstantTCC” whereby the pneumaticwalking boot is applied, thenwrapped with a roll of plaster as adeterrent so the patient does not

remove the walk-er. If he or shedoes, I will easilyknow.

Both the TCCand the remov-able walkersshould slow thepatient down.One study hasd e m o n s t r a t e dwhen walkingspeed is reduced

from 1.19 m/s to 0.83 m/s, peakplantar pressures are reduced 10% atthe forefoot and 5-18% in the heel.(2)

Rule of ThumbThe rule of thumb which is

quickly emerging in wound care isthat the wound should reduce by50% within four weeks. If it failsto do so, you should reconsideryour treatment plan or re-evaluatethe patient’s vascular status, con-

to multiple applications, is rela-tively time-consuming, and has ahigh potential for iatrogenic le-sions. I usually recommend at-tending a TCC workshop and thenworking with a podiatrist in yourarea who util izes the cast fre-quently, and becoming very famil-iar and comfortable with it priorto utilizing the TCC on your pa-tients. Typically, I will debride thewound and apply the appropriatedressing, keeping it as thin as pos-sible. I apply the cast and have thepatient back in three days tocheck for fit and possible piston-ing in the cast due to edema re-duction. Once all edema is re-moved, I generally have patientsback once a week to once everytwo weeks depending on compli-ance and wound drainage. TheTCC is, however, contraindicatedin patients with peripheral arterialdisease, wound infection, os-teomyelitis and wounds which aredeeper than they are wide.

The TCC has the shortest doc-umented healing time of all theoff-loading modalities. In severalstudies, as well as the one by Linnmentioned earlier, the averagenon-infected plantar forefootulcer will close within 45 days in aTCC. This is compared to 70 daysfor a half shoe, 90 days for felted-foam, 108 daysfor a custom-molded shoe,and 300 days forcustom splints. Astudy by Lavery,et al., comparedthe mean peakpressure underthe 1st and 2ndmetatarsal headsas well as theplantar hallux,while patients wore a TCC, DHPressure Relief walker®, Aircastpneumatic walker®, 3D® Dura Step-per, CAM walker, added-depthshoe, and a canvas sneaker.(8)

Studies of all the locationsfound that the TCC and the walk-ers were very effective at off-load-ing the plantar forefoot. Pressurereduction for both devices was es-sentially equal. Healing times forTCC, however, are significantly

Diabetic Foot... sider bacterial woundcolonization or re-visit thecurrent off-loading. Thereare, however, some plantar le-sions, which, despite the best andmost appropriate off-loading, sim-ply will not heal. The most com-mon locations for these lesions are

the lateral andcentral midfoot.When presentedwith an open le-sion at the plan-tar midfoot sec-ondary to achronic but plan-tar grade and sta-ble Charcot, off-loading is biome-chanically diffi-cult. The walkersare rarely effec-tive due to therocker nature of

the Charcot foot. The TCC is thebest device in this situation; how-ever, obtaining healing can be dif-ficult. After a course of unsuccess-ful TCC, surgical interventionmay be necessary. Rosenblumpublished a study in which heevaluated 32 feet on 31 patientswith chronic non-healing diabeticfoot ulcers at the plantar lateralmidfoot, all of whom had failedconservative care.(25) All underwentplantar exostectomy with an over-all success rate of 89%. Catanzaritialso reported on 27 procedures on20 patients, 18 medial and 9 later-al.(26) 20 of the 27 patients healedprimarily with 6 of the 7 being lat-eral column, requiring revisionalsurgery.

SummaryIn summary, there are several

important considerations whenoff-loading the diabetic foot. Con-sider not only peak plantar pres-sure, but also load cycles and themechanics resulting in increasedtime the load is applied. Evaluatethe foot and ankle for limitedjoint mobility at the 1st MPJ aswell as the ankle joint. Consider apercutaneous TAL in patients withankle joint equines, which is in-hibiting the off-loading effortsand preventing healing. Select thebest off- loading device for the pa-tient; provide information on


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The rule of thumb in wound care is that the

wound should reduce by 50% within

four weeks.

Consider not only peak plantar

pressure, but also load cycles

and the mechanics resulting in

increased time the load is applied.

diabetic foot ulceration. Diabetes Care.1991 Jan;14(1):8-11.

20 Young MJ, Cavanagh PR, ThomasG, Johnson MM, Murray H, Boulton AJ:The effect of callus removal on dynamicplantar foot pressures in diabetic patients.Diabet Med. 1992 Jan-Feb;9(1):55-7.

21 Lavery LA, Armstrong DG, BoultonAJ; Diabetex Research Group: Ankle equi-nus deformity and its relationship to highplantar pressure in a large populationwith diabetes mellitus. J Am Podiatr MedAssoc. 2002 Oct; 92(9):479-82.

22 Lin SS, Lee TH, Wapner KL: Plantarforefoot ulceration with equinus deformi-ty of the ankle in diabetic patients: the ef-fect of tendo-Achilles lengthening andtotal contact casting. Orthopedics. 1996May; 19(5):465-75.

23 Armstrong DG, Stacpoole-Shea S,Nguyen H, Harkless LB: Lengthening ofthe Achilles tendon in diabetic patientswho are at high risk for ulceration of thefoot. J Bone Joint Surg Am. 1999 Apr;81(4):535-8

24 Bledsoe Brace Systems, by MedicalTechnology Inc., 2601 Pinewood, GrandPrairie, TX 75051

25 Rosenblum BI, Giurini JM, MillerLB, Chrzan JS, Habershaw GM:Neuropathic ulcerations plantar to the lat-eral column in patients with Charcot footdeformity: a flexible approach to limb sal-vage. J Foot Ankle Surg. 1997 Sep-Oct;36(5):360-3

26 Catanzariti AR, Mendicino R,Haverstock B: Ostectomy for diabetic neu-roarthropathy involving the midfoot. JFoot Ankle Surg. 2000 Sep-Oct; 39(5):291-300.

27 Lavery LA, Fleishli JG, Laughlin TJ,Vela SA, Lavery DC, Armstrong DG.: Ispostural instability exacerbated by off-loading devices in high risk diabetics withfoot ulcers? Ostomy Wound Manage.1998 Jan; 44(1):26-32, 34.

28 Pitei DL, Foster A, Edmonds M.:The effect of regular callus removal onfoot pressures. J Foot Ankle Surg. 1999Jul-Aug;38(4):251-5.


Diabetic Foot...

wound size and location, thefoot structure, the patient’s job,

home environment, and othermedical or ambulatory conditions.

If the woundfails to progressdespite lack of in-fection and os-teomyelitis andthe presence ofadequate vascularstatus, considerinadequate off-loading as amajor issue. Thiscan be due to theselection of aninappropriate de-vice or the pa-tient’s non-com-pliance with theselected device.Most non-com-plicated plantar ulcers will re-spond quickly with appropriateoff-loading. ■

References1 Brand PW: The insensitive foot.

Seminars and Lecture Series on the Insen-sitive Foot, U.S. Public Health Service Hos-pital, Carville, LA

2 Van Deursen R: Mechanical loadingand off-loading of the plantar surface ofthe diabetic foot. Clin Infect Dis. 2004Aug 1;39 Suppl 2:S87-91.

3 Commean PK, Mueller MJ, SmithKE, Hastings M, Klaesner J, Pilgram T,Robertson DD: Reliability and validity ofcombined imaging and pressures assess-ment methods for diabetic feet. Arch PhysMed Rehabil. 2002 Apr;83(4):497-505.

4 Drerup, B, Kolling Ch, Koller a,Wetz HH: Reduction of plantar peak pres-sure by limiting stride length in diabeticpatients. Orthopade. 2004 Sep;33(9):1013-9. German.

5 Ledoux WR, Shofert JB, Ahroni JH,Smith DG, Sangeorzan BJ, Boyko RBiomechanical differences among pescavus, neutrally aligned, and pes planusfeet in subjects with diabetes. Foot AnkleInt. 2003 Nov;24(11):845-50.

6 Zimny S, Schartz H, Pfohl U: The ef-fects of applied felted foam on woundhealing and healing times in the therapyof neuropathic diabetic foot ulcers. DiabetMed. 2003 Aug;20(8):622-5.

7 Armstrong DG, Lavery L, KimbrielH, Nixon BP, Boulton AJ: Activity pat-terns of patients with diabetic foot ul-ceration: patients with active ulcerationmay not adhere to a standard pressureoff-loading regimen. Diabetes Care.

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2003 Sep; 26(9):2595-7.8 Lavery L, Vela SA, Lavery DC,

Quebedeaux TL: Total contact casts: pres-sure reduction at ulcer sites and the effecton the contralateral foot. Arch Phys MedRehabil. 1997 Nov;78(11):1268-71.

9 Walker SC,Helm PA, Pullium G:Total contact castingand chronic diabeticneuropathic foot ul-cerations: healingrates by wound loca-tion. Arch Phys MedRehabil. 1987Apr;68(4):217-21.

10 Lavery L, VelaSA, Lavery DC,Quebedeaux TL: Re-ducing dynamic footpressures in high-riskdiabetic subjectswith foot ulcera-tions. A comparisonof treatments. Dia-betes Care. 1996Aug;19(8):818-21.

11 Myerson M, Papa J, Eaton K, Wil-son K: The total-contact cast for manage-ment of neuropathic plantar ulceration ofthe foot. J Bone Joint Surg Am. 1992Feb;74(2):261-9.

12 Armstrong DG, Nguyen HC, LaveryL, van Schie CH, Boulton AJ, Harkless LB:Off-loading the diabetic foot wound: arandomized clinical trial. Diabetes Care.2001 Jun;24(6):1019-22. Erratum in: Dia-betes Care 2001 Aug;24(8):1509.

13 Mueller MJ, Diamond JE, SinacoreDR: Total contact casting in treatment ofdiabetic plantar ulcers. Controlled clinicaltrial. Diabetes Care. 1989 Jun;12(6):384-8.

14 Mueller, MJ, Sinacore DR, HastingsMK, Strube MJ, Johnson JE, Effects ofAchilles tendon lengthening on neuro-pathic plantar ulcers, J. Bone Joint Sur-gery, Vol 85-A, Number 8, August 2003.

15 Chanetelau E, Breuer U, Leisch AC,Tanudjaja T, Reuter M: Outpatient treat-ment of unilateral diabetic foot ulcerswith ‘half shoes’. Diabet Med. 1993Apr;10(3):267-70.

16 Duckworth T, Boulton AJ, Betts RP,Franks CI, Ward JD: Plantar pressure mea-surements and the prevention of ulcera-tion in the diabetic foot. J Bone Joint SurgBr. 1985 Jan;67(1):79-85.

17 Stess RM, Jensen SR, Mirmiran R.The role of dynamic plantar pressures indiabetic foot ulcers. Diabetes Care. 1997May;20(5):855-8.

18 Vela SA, Lavery LA, Armstrong DG,Anaim AA: The effect of increased weighton peak pressures: implications for obesityand diabetic foot pathology. J Foot AnkleSurg. 1998 Sep-Oct;37(5):416-20.

19 Fernando DJ, Masson EA, Veves A,Boulton AJ: Relationship of limited jointmobility to abnormal foot pressures and

Dr. Vincent Giacalone is agraduate ofNYCPM and isboard certifiedby the Ameri-can College ofFoot and AnkleSurgeons. He iscurrently in pri-vate practice atthe Diabetic Foot Care Center in Emer-son, NJ., and the Diabetes Foot andAnkle Center of The Hospital For JointDiseases in New York City. Dr. Gi-acalone is a member of the APMA andthe American Diabetes Association.

If the wound fails toprogress despite lack

of infection andosteomyelitis

and the presence of adequate

vascular status, consider inadequate

off-loading as a major issue.


5) The typical post-operativeshoe is not efficient at off-loadinga plantar forefoot ulcer due to:

A) There is little to no shockabsorptionB) The fact that the sole isflexible and it does not lockthe ankle jointC) Inability to tighten theVelcro closuresD) The rigid sole of the shoe

6) Which of the following is notone of the three mechanisms ofinjury resulting in a plantar ul-ceration?

A) Low pressure over a shortperiod of timeB) High pressure over a shortperiod of timeC) Moderate repetitive pres-sureD) Low pressure over a longperiod of time

7) The following are the mostcommon reasons for woundhealing failure except;

A) Peripheral arterial diseaseB) InfectionC) Elevated blood glucoseD) Inadequate off-loading

8) In order to evaluate a patien-t’s potential for ulcer develop-ment all of the following shouldbe considered except:

A) Amount of pressureplaced on the areaB) Number of load cycles orstepsC) Amount of time the areais loadedD) Patient’s age

9) Pressure in a callused area maybe reduced by what percentageafter callus debridement?

A) 15-22%B) 24 – 32%C) 16-29%D) 44-68%

1) The total contact cast (TCC)and removable walking bootshave similar off-loading profileswhen tested, yet clinically theTCC heals ulcers in a shorter pe-riod of time due to:

A) The walking boot causededemaB) The walking boot causespatients to limp due to aheight differenceC) Patients have an increasedstride length while in the TCCD) Forced patient compliancewhile in the TCC

2) In order to determine tissuebreakdown threshold, plantarpeak pressure must be evaluatedwith the following:

A) Number of load cycles orsteps the patient takes perdayB) The amount of times theulcer is debridedC) The patient’s vascular sta-tusD) The patient’s age andweight

3) Plantar forefoot ulcers whichfail to heal may be due to whichof the following:

A) Inappropriate dressingB) Ulcer of over 3 months du-rationC) Limited ankle joint dorsi-flexion / ankle equinusD) Prior use of broad spec-trum antibiotics

4) Biomechanically, the mostsuccessful devices for off-loadingthe plantar forefoot acceleratehealing due to their ability to:

A) Lock the ankle joint andprevent plantar-flexion dur-ing push-offB) Increase weight-bearing inthe heelC) Limit patients’ activityD) Prevent edema

10) Limited joint mobility mayaffect all of the following jointsexcept:

A) Subtalar jointB) Ankle jointC) Fist MPJD) Affects all of the above

11) Limited joint mobility occursin the joints due to:

A) Muscle fiber stenosisB) Muscle denervationC) Glycosolation of collagenfibersD) Auto tenodesis

12) A patient with diabetes anda sub hallux ulcer and limitedfirst MPJ motion without radio-graphic evidence of first ray ele-vatus or first MPJ bony blockmay have:

A) OsteomyelitisB) Pseudo-limitusC) Limited joint mobility atthe first MPJD) Limb length discrepancy

13) Felted foam dressing maybe best used to off-load anulcer in:

A) Young active patientsB) Older patients with re-duced push-offC) Patients with a midfootcharcotD) Patient with underlyingosteomyelitis

14) The following are disadvan-tages in using a post op shoe fora plantar ulcer except:

A) Lack of biomechanical stabilityB) Allows for shear and frictionC) Problems with fitting andslippageD) Easily modified

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See answer sheet on page 263.


262 PODIATRY MANAGEMENT

15) In the lab removable walking boots havepressure reduction similar to a total contactcast. Clinically, however, the cast has superiorwound healing rates. This is most likely due to:

A) The fact that most patients remove thewalking boot sometime during the dayB) The inability of the boot to lock the anklejointC) The fact that the walking boot has a rollersoleD) The fact that the cast is heavier than thewalking boot

16) One of the reasons a total contact cast is ef-fective is due to its ability to reduce pressure by:

A) Decreasing the area the force is appliedtoB) Increasing the area the force is applied toC) Increasing the force under the footD) Reducing edema in the foot

17) By asking a patient to reduce his/her stridelength by approximately 25%, plantar pressurecan be reduced by:

A) 90%B) 45%C) 14.5%D) 39%

18) All of the following are contraindications tothe use of a total contact cast except:

A) An ulcer which is deeper than it is wideB) Acute infectionC) Peripheral arterial diseaseD) Edema

19) When using a total contact cast or walkingboot, pressure on the contra-lateral foot is oftenreduced due to:

A) Reduced cadence and stride lengthB) Weight of the walker or castC) Bulkiness of the dressingD) Height of the walker or cast

20) Most foot ulcers are caused by a combina-tion of the following:

A) Trauma and peripheral arterial diseaseB) Peripheral neuropathy and traumaC) Peripheral neuropathy and peripheral ar-terial diseaseD) Peripheral arterial disease and tight shoes

E X A M I N A T I O N

(cont’d)

See answer sheet on page 263.

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E N R O L L M E N T F O R M & A N S W E R S H E E T (cont’d)Con

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LESSON EVALUATION

Please indicate the date you completed this exam

_____________________________

How much time did it take you to complete the lesson?

______ hours ______minutes

How well did this lesson achieve its educational objectives?

_______Very well _________Well

________Somewhat __________Not at all

What overall grade would you assign this lesson?

A B C D

Degree____________________________

Additional comments and suggestions for future exams:

__________________________________________________

__________________________________________________

__________________________________________________

__________________________________________________

__________________________________________________

__________________________________________________

EXAM #2/06A Review of Topical Corticosteroids

(Smith)

1. A B C D

2. A B C D

3. A B C D

4. A B C D

5. A B C D

6. A B C D

7. A B C D

8. A B C D

9. A B C D

10. A B C D

11. A B C D

12. A B C D

13. A B C D

14. A B C D

15. A B C D

16. A B C D

17. A B C D

18. A B C D

19. A B C D

20. A B C D

Circle:

LESSON EVALUATION

Please indicate the date you completed this exam

_____________________________

How much time did it take you to complete the lesson?

______ hours ______minutes

How well did this lesson achieve its educational objectives?

_______Very well _________Well

________Somewhat __________Not at all

What overall grade would you assign this lesson?

A B C D

Degree____________________________

Additional comments and suggestions for future exams:

__________________________________________________

__________________________________________________

__________________________________________________

__________________________________________________

__________________________________________________

__________________________________________________

EXAM #3/06Off-Loading the Diabetic Foot

(Giacalone)

1. A B C D

2. A B C D

3. A B C D

4. A B C D

5. A B C D

6. A B C D

7. A B C D

8. A B C D

9. A B C D

10. A B C D

11. A B C D

12. A B C D

13. A B C D

14. A B C D

15. A B C D

16. A B C D

17. A B C D

18. A B C D

19. A B C D

20. A B C D

Circle:

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