The Foot in Diabetes - part 7 docx

PRE-OPERATIVE ASSESSMENT One of the aims of the St Vincent Declaration on diabetes care made by theWorld Health Organization and International Diabetic Federation in 1991was a reduction

chamber held in contact with the skin The TcPO2is measured using a probe

to measure the PO2in the solution A low TcPO2re¯ects the degree of tissueischaemia and increases with successful intervention In diabetes, TcPO2 islower than in the matched arteriopathic patients, a TcPO 2 of less than

40 mmHg is associated with failure of wound healing, and increased TcPO 2

after intervention predicts success of angioplasty and wound healing moreaccurately than changes in ABPI9

Doppler Waveform Analysis

In peripheral vascular disease, the normal, triphasic, waveform detectableusing Doppler waveform analysis is damped distal to haemodynamicallysigni®cant lesions In diabetes, damping of the waveform may indicatePVD; however, diabetic neuropathy has been shown to be related toabnormalities of Doppler waveform in the dorsalis pedis artery in theabsence of PVD10

Colour Duplex Sonography (CDS)

Ultrasound of the peripheral vascular system has been greatly enhanced byduplex-Doppler imaging Ultrasound imaging, enhanced by colour ¯owrepresentation and Doppler waveform analysis, can be used to detect andcharacterize haemodynamically signi®cant lesions in larger vessels with90% accuracy and predicts ®nal surgical intervention as accurately as doesangiography It has therefore been suggested that CDS may replace contrastangiography in the investigation of PVD11 Ultrasound resolution at presentlimits its use in assessing distal vessels for limb salvage procedures;however, no single modality can accurately identify foot vessels as suitablefor a distal anastomosis

Contrast Angiography

Non-invasive investigation, using a combination of modalities, can in mostcases detect clinically signi®cant ischaemia and will identify most lesions ofthe larger vessels that are amenable to intervention At present, however,despite full non-invasive investigation it is impossible to exclude surgicallycorrectable lesions because of the problems of imaging disease in, anddetermining patency of, distal vessels

Angiography offers a further imaging modality which may help with theassessment of the distal vasculature but also provides a ``road map'' forplanning surgical intervention It is therefore indicated in cases of delayedulcer healing as well as those in which preliminary vascular assessment has

identi®ed signi®cant ischaemia Best quality images are obtained with arterial digital subtraction angiograms, with antegrade studies if necessary.

intra-Magnetic Resonance Angiography (MRA)

The developing technology of magnetic resonance imaging is now beginning

to offer accurate vascular imaging as an alternative to contrast angiography.The development of gadolinium enhancement and protocols for time-of-

¯ight analysis has resulted in high-resolution MRA which may, in the future,replace angiography12 MRA can now accurately detect haemodynamicallysigni®cant stenoses and occlusions and can resolve images of digital vesselsand run-off vessels 1 mm in diameter Availability of MRA currentlyprevents its routine use; in selected cases, however, it may offer an importantimaging modality and increasing use seems likely

PRE-OPERATIVE ASSESSMENT

One of the aims of the St Vincent Declaration on diabetes care made by theWorld Health Organization and International Diabetic Federation in 1991was a reduction in rates of major lower limb amputation for diabeticgangrene13 Achieving this goal requires a rigorous approach to limbsalvage based on medical, paramedical and surgical intervention and care.The elderly diabetic population in whom diabetic foot diseases occur areaffected by many other medical problems Assessment and control of thesefactors is important for successful limb salvage and patient survival aftervascular reconstruction

Ischaemic Heart Disease

Pre-operative assessment of patients for peripheral vascular reconstructionshould routinely include assessment of cardiac status, including history ofhypertension, angina and myocardial infarction (MI) and ECG In diabeticpatients, previous symptomatic ischaemic heart disease (IHD) carries afour-fold risk of cardiac complication However, previously asymptomaticindividuals contribute signi®cantly to the 5% overall risk of MI or cardiacdeath14 Previous ``silent'' MI may produce an unsuspectedly poor cardiacreserve, and slow post-operative recovery may re¯ect a peri-operativeischaemic event

Cerebrovascular Disease

Previous severe disabling stroke would be a relative contra-indication tomajor vascular reconstruction for limb salvage for patients who would

return rapidly to their usual state of wheelchair mobility by consideringprimary amputation.

Renal Impairment

Impaired renal function as a result of renal artery or small vessel disease is

an important factor in vascular assessment Contrast arteriography carrieswith it signi®cant risks of renal failure or increased renal impairment,particularly in patients with existing impaired renal function and diabetes.For these patients it is particularly important to maintain good urine output,using intravenous ¯uids to maintain hydration Diuretics are used in someregimens for renal protection; however, loop diuretics have been linked toadverse effects on renal function in some studies MRA and CO2arteriography15 may, in the future, be important modes of investigation inpatients at particular risk of renal complications Close operativemonitoring of renal function is also essential in this group of patients

Proliferative Retinopathy

Diabetic retinopathy may in¯uence decisions regarding the use ofthrombolysis to salvage occluded grafts Thrombolysis carries a risk ofsight-threatening occular haemorrhage

Diabetic Control

In the presence of signi®cant sepsis, diabetic control is frequently lost andsome patients are at potential risk of developing diabetic keto-acidosis Theacute presentation of the diabetic foot may also be heralded bydevelopment of uncontrolled diabetes Methods of diabetes control in theperi-operative period vary and several methods can be utilized In thesetting of poor glycaemic control due to sepsis, a regimen of intravenousdextrose and potassium with an intravenous sliding scale of insulin based

on blood glucose measurements is frequently employed

Risk of Infection

Some of the factors that contribute to the development of foot ulcers alsoresult in increased risks of complications following surgical intervention.Long-standing diabetes is associated with poor wound healing, which may

be related to poor nutrient transfer due to small vessel disease.Additionally, diabetes, particularly when poorly controlled, is associatedwith increased susceptibility to wound infection The combination of poorwound healing and susceptibility to wound infection may require an

alternative antibiotic policy and extra vigilance for wound-relatedcomplications The risks of wound-related complications are also importantwith respect to the use of prosthetic graft materials for reconstruction.

VASCULAR SURGERY FOR THE DIABETIC FOOT

General Considerations

Major vascular reconstruction requires prolonged anaesthesia and sents a signi®cant risk of major postoperative morbidity and mortality,particularly in patients with other long-term complications Surgicalplanning should therefore include consideration of the minimal interven-tion that will achieve successful healing and control of symptoms and, ifvascular reconstruction is indicated, whether the probability of success andrisk of complications are acceptable Planning surgery should attendparticularly to the arterial in¯ow to the limb, the availability of a suitabledistal out¯ow vessel for anastomosis, and the surgery required to removedevitalized or infected tissue from the distal extremity to allow healing.Consideration should also be given to the alternatives to generalanaesthesia that are available in high-risk patients Techniques of regionalanaesthesia, including spinal and epidural methods, may be suitable forselected patients and selected operations, although not when cephalic andbasilic veins are to be obtained and used as a graft conduit

repre-An important aspect of planning surgical intervention is the immediacy

of the clinical situation The presentation ranges from chronic ulceration tofulminant limb-threatening infection In chronic cases, vascular reconstruc-tion may only be a consideration if more conservative methods fail toachieve ulcer healing More acute presentations will require a rapidassessment of the prospect for limb salvage, the role of tissue debridementand vascular intervention

The Emergency Diabetic Foot

For patients presenting with rapidly progressive tissue loss due to infectionand/or ischaemia, the disease process represents a signi®cant risk of limbloss and mortality A rapid assessment is required of whether the degree ofnecrosis and infection can be controlled by local debridement or minoramputation and, second whether ischaemia is an aetiological factor In theacute situation, the diagnosis of ischaemia may not be possible beforeintervention to control localized infection and, if major amputation is notrequired due to extensive necrosis of the weightbearing areas, drainage anddebridement can be undertaken as a primary procedure

After local control of infection, and because of the dif®culties ofdiagnosing ischaemia non-invasively, an intensive vascular assessmentwill frequently be indicated Colour duplex ultrasound may satisfactorilyidentify lesions suitable for angioplasty in many situations; however,angiography will be more readily available and will, in any case, berequired to perform angioplasty and assess the arterial system forreconstructive surgery Depending upon the patient's premorbid condition,the extent of the necrosis and infection, and the pattern of any arterialdisease, a decision can be made as to the best combination of angioplasty,stent insertion, debridement, endovascular and vascular surgical recon-struction.

Planning Vascular Surgery (Table 16.2)

In¯ow

Planning vascular surgery in suitable patients follows the basic principle ofcorrection of haemodynamically signi®cant proximal lesions before moredistal disease The success of any reconstruction below the inguinalligament is largely dependent on satisfactory in¯ow and in some cases,even with signi®cant distal arterial disease, improved in¯ow to a limb may

be suf®cient to allow healing Radiological intervention, such aspercutaneous transluminal angioplasty (PTA) and stenting of iliac lesions,

is dealt with in Chapter 15

Surgical approaches to in¯ow disease are divided into those designed toimprove ¯ow through native vessels and operations that bypass diseased or

Table 16.2 Cascade of surgical and radiological intervention for PVD (proximal

before distal)

Focal lesions stenosis/short segment

occlusion Optimization of in¯ow and limb perfusion byradiological intervention Iliac disease without iliac in¯ow Aorto-(bi-)iliac

Aorto-(bi-)femoral Axillo-(bi-)femoral Iliac disease with ipsilateral in¯ow Ipsilateral iliofemoral

Iliac disease with contralateral in¯ow Contralateral iliofemoral

Femoro-femoral cross-over Femoral artery bifurcation disease Profundaplasty

Endarterectomy Femoropopliteal disease Femoropopliteal (AK)

Femoropopliteal (BK) Popliteal trifurcation disease SFA/popliteal±crural

Femorocrural Crural disease SFA/popliteal pedal

Femoropedal

SFA=super®cial femoral artery.

occluded vessels Focal stenosis due to atheroma can reduce ¯ow throughnative vessels and may not always be suitable for radiological intervention.This commonly occurs at the bifurcation of the common femoral artery intoprofunda femoris and the super®cial femoral artery In this position PTArisks occluding the branch arteries, which can worsen the situation Thestenosis can be corrected by a surgical angioplasty The exposed andclamped artery is opened longitudinally over the stenotic segment,atheroma is removed from the three vessels by careful endarterectomy,and the arteriotomy closed using a patch of native vein or synthetic materialsuch as dacron The arteriotomy and patch closure can be extended onto theprofunda femoris to perform a profundaplasty.

Operations to improve in¯ow by bypassing iliac occlusive diseaseinclude iliofemoral bypass, contralateral or unilateral as appropriate, andfemoro-femoral cross-over Similarly, for bilateral disease, transabdominalaorto-(bi-)iliac or (bi-)femoral bypass represent major surgical interven-tions, whereas axillo-(bi-)femoral bypass offers a less invasive, buthaemodynamically inferior, procedure Improved proximal in¯ow may besuf®cient to promote healing and relieve symptoms Once satisfactoryin¯ow has been achieved, infra-inguinal reconstruction may be appropriate

to improve more distal circulation

The longevity of the graft is partially dependent upon the level andquality of the out¯ow vessel (Figures 16.3, 16.4) The distal vessel may beidenti®ed by dependent Doppler ultrasound, pulse-generated run-off or onarteriographic images and these all give information about the quality of thedistal vessel and the run-off from it

The decision as to the level of the distal anastomosis depends upon thelevel and quality of the available distal vessels Patency is better for grafts tomore proximal vessels This observation, however, may re¯ect the morelimited disease pattern seen in patients with suitable vessels at this level.Anastomosis to a diseased vessel is technically demanding and risks earlygraft occlusion because of disease close to the anastomosis and, therefore,anastomosis to a healthy, more distal vessel is essential if one is available(Figures 16.3, 16.4) For distal vascular reconstructions, an important

component of arterial run-off is the dorsal pedal arch An angiographicallyintact arch is an important determinant of the success and survival of a graft

to the distal vessels20

In diabetic patients, the prevalence of disease in the tibial vessels dictates

a femorodistal approach more frequently than in the general population

Figure 16.3 Selection of out¯ow vessel for infra-inguinal reconstruction The digitalsubtraction angiogram shows a patent below knee popliteal artery but with severelydiseased run-off in all three tibial vessels (a) which occlude in the calf Collateralvessels reconstitute just above the ankle in a peroneal artery with patent, butdiseased, anterior and posterior branches In this case a graft to the below kneepopliteal is at high risk of occlusion due to poor run-off (b); however, the less thanperfect ankle vessel makes a decision regarding distal anastomosis a dif®cult one

The relative sparing of foot vessels from the atherosclerotic process indiabetes makes femoropedal surgery a relatively frequent option inreconstruction.

Choice of ConduitÐAutogenous Vein Should be Used Whenever PossibleInfra-inguinal bypass is technically feasible using either autogenous vein orsynthetic materials, such as expanded polytetra¯uoroethylene (PTFE), as aconduit General vascular surgical practice favours the use of autogenous

Figure 16.4 Healthy distal vessel for out¯ow anastomosis In a limb displayingotherwise severe atheromatous disease, a patent and angiographically healthyanterior tibial/dorsalis pedis artery running into a patent pedal arch is available fordistal anastomosis

vein whenever possible because long-term patency is signi®cantly better forvein grafts In diabetic patients, the preferential use of autogenous vein isparticularly important because of an increased risk of occlusion21 Suchpatients are also at increased risk of prosthetic graft infection, which carries

a signi®cant risk of amputation and death

The ipsilateral long saphenous vein (LSV) offers the ®rst source ofautogenous vein; a satisfactory vessel may be used, employing in situ,reversed or non-reversed techniques, depending upon the quality anddimensions of the vessel and the anatomical bypass type In the absence of asuitable vessel, however, the contralateral LSV, the short saphenous, basilicand cephalic veins or grafts spliced using vein from different sources are allavailable as sources of autogenous material before a synthetic graft must becontemplated

The result of these deliberations should be a planned procedure that willprovide durable revascularization to the extremity and improve the rateand probability of healing of that extremity The patient should understandthe principles of the procedure, the potential bene®ts and also the risksassociated with the surgery

Surveillance

Occlusion of infra-inguinal bypass grafts leading to recurrent footischaemia requires major intervention Thrombolytic therapy may achievegraft patency but there is a signi®cant risk of haemorrhagic complicationslocally and systemically, including fatal or disabling intracerebral bleeding.Patients in whom thrombolysis cannot be used or in whom it fails willrequire further bypass surgery or risk amputation22

In order to reduce graft failure rates, graft surveillance is undertaken todetect haemodynamically signi®cant lesions in in¯ow or out¯ow vessels orthe graft itself In the outpatient situation, repeated measures of the ABPImay detect a falling foot perfusion and indicate the need for furtherinvestigation The gold standard for non-invasive graft surveillance,however, is duplex scanning23,24 A postoperative duplex scan performed

in the ®rst week after operation followed by further scans at intervals of 4weeks, 3, 6, 9 and 12 months, and 6 monthly thereafter, can be used to detectlesions requiring correction to prevent graft failure Detected lesions arefurther investigated, frequently with angiography, and amenable lesionscorrected by radiological or surgical means Successful correction isfollowed by continued graft surveillance (Figure 16.5)

Results of Infra-inguinal Reconstruction in Diabetics

With close attention to pre-operative assessment, surgical planning, surgicaltechnique and interventional graft surveillance, excellent rates of secondary

graft patency (82±98%) and limb salvage (76±89%) can be achieved (Table16.3) Graft patency and limb salvage rates are similar to those for non-diabetic patients31±33.

ADJUNCTIVE PLASTIC SURGERY

For the majority of patients undergoing peripheral vascular reconstruction,improved tissue perfusion and good nursing care will allow healing of anulcer or minor amputation wound Even in cases where a minor amputation

Figure 16.5 High grade stenosis in femoro-distal bypass graft Three years after afemoro-dorsalis pedis graft using a composite vein graft a high grade stenosis,which required surgical intervention, was detected, on duplex surveillance, at thejunction between the two segments of vein used

wound has been left open because of local residual infection, delayedclosure or healing by secondary intention will frequently eventually achieve

a satisfactory result

In some cases, however, healing may be achieved more rapidly usingadjunctive plastic surgical techniques Early resolution of the pain fromulcers or amputation sites is an aid to early mobilization and, therefore,rehabilitation An intact epithelial surface is also an important barrier tofurther infection, which may delay wound or ulcer healing

Split SkinGrafting

Split skin grafting may be useful in order to expedite healing of ulcers andareas of wound breakdown where healthy granulation tissue is present Thegraft, which consists of the epidermis and super®cial capillary dermis, is cutfrom the donor area using a dermatome and transferred to the recipient site.The donor site heals by regrowth of the skin from epidermal appendagesnot removed by the dermatome, such as hair follicles Perforation of thegraft and an appropriate dressing prevent separation of the graft from thehealthy vascular bed and ensure maximum ``take''

Free Tissue Transfer6

In cases where deep ulceration or infection require extensive debridement

or minor amputation, surgery may leave bone exposed and remaininghealthy tissue may not be suf®cient to achieve primary or secondary

Table 16.3 Results of infra-inguinal bypass in diabetic patients

(%) Details Follow-up

(months)

Primarypatency(%)

Secondarypatency(%)

Limbsalvage(%)

Survival(%)

closure In these cases, secondary healing will also be delayed and there is aparticular risk of limb-threatening infection where bone is exposed; suchwounds are unsuitable for split skin grafting because of the lack of a highlyvascular recipient site In some of these cases early primary or secondaryclosure can be achieved by free tissue transfer.

Free tissue transfer involves the isolation of a pedicle of tissue consisting

of blood supply, overlying skin and the underlying vascular bed, frequently

a muscle The vessels of the myocutaneous ¯ap are anastomosed to suitablein¯ow and drainage vessels These may be native vessels or, in the case ofvascular surgical cases, in¯ow may be from a graft The ¯ap can then beused to close the skin defect on the limb

Donor sites for free ¯aps include the radial aspect of the forearm, theparascapular region, latissimus dorsi, temporalis and rectus abdominis Ineach of these sites tissue can be obtained with a reliable anatomic bloodsupply Removal of the tissue and supplying vessels does not compromiselocal blood supply or signi®cantly affect the function of the remainingmuscle groups Choice of donor site depends upon the area and volume ofskin coverage required and factors related to patient and surgeonpreferences

Myocutaneous free ¯aps achieve rapid coverage of the tissue defect andprovide a mass of healthy tissue with a good blood supply in the area ofischaemic damage The operative procedure, however, is associated withmarked haemodynamic and surgical stresses and frequently requires asecond prolonged anaesthetic The procedure is frequently best delayeduntil the bypass graft has demonstrated early patency and satisfactoryradiological imaging This also allows control of local infection by the initialdebridement and revascularization and further debridement of non-viabletissue at the time of second operation, and reduces the risk of loss of the ¯apdue to early failure of graft

SYMPATHECTOMY

In some cases, arterial disease is so extensive as to preclude any sort ofarterial reconstruction and for some of these patients, who have extensiveinfection or necrosis, major amputation is required For others, however,although circulation is tenuous, the ulcers are painful and healing isextremely slow, although limb loss is not inevitable In these patientsinterruption of the sympathetic nerve supply to the vessels of the lowerlimb, producing vasodilatation, can be used to increase limb blood ¯ow.Open lumbar sympathectomy using an extraperitoneal operative approachhas largely been superseded by sympathetic ablation, by injection of phenolunder ¯uoroscopic control The procedure produces rapid increases inblood ¯ow and limb temperature and is associated with pain relief and

ulcer healing in 58% of patients34 Bene®t may still be obtained in thediabetic patient who appears to have already lost sympathetic tone.

REFERENCES

1 O'Neal DN, Lewicki J, Ansari MZ, Matthews PG, Best JD Lipid levels andperipheral vascular disease in diabetic and non-diabetic subjects Atherosclerosis1998; 136: 1±8

2 Kamal K, Powell RJ, Sumpio BE The pathobiology of diabetes mellitus:implications for surgeons J Am Coll Surg 1996; 183: 271±89

3 Brown AS, Hong Y, de Belder A et al Megakaryocyte ploidy and plateletchanges in human diabetes and atherosclerosis Arterioscler Thromb Vasc Biol1997; 17: 802±7

4 LoGerfo FW, Gibbons GW Vascular disease of the lower extremities indiabetes mellitus Endocrinol Metabol Clin N Am 1996; 25: 439±45

5 Gibbons GW Vascular evaluation and long-term results of distal bypasssurgery in patients with diabetes Clin Podiat Med Surg 1995; 12: 129±40

6 Karp NS, Kasabian AK, Siebert JW, Eidelman Y, Colen S Microvascular

free-¯ap salvage of the diabetic foot: a 5-year experience Plastic Recon Surg 1994; 94:834±40

7 Rutherford RB, Baker JD, Ernst C et al Recommended standards for reportsdealing with lower extremity ischemia: revised version J Vasc Surg 1997; 26:517±38

8 Apelqvist J, Castenfors J, Larsson J, Stenstrom A, Agardh C-D Prognosticvalue of systolic ankle and toe blood pressure levels in outcome of diabetic footulcer Diabet Care 1989; 12: 373±8

9 Hanna GP, Fujise K, Kjellgren O et al Infrapopliteal transcatheter tions for limb salvage in diabetic patients: importance of aggressiveinterventional approach and role of transcutaneous oximetry J Am Coll Cardiol1997; 30: 664±9

interven-10 Chew JT, Tan SB, Sivathasan C, Pavanni R, Tan SK Vascular assessment in theneuropathic diabetic foot Clin Orthopaed Rel Res 1995; 3/2: 95±100

11 Aly S, Sommerville K, Adiseshiah M, Raphael M, Coleridge SP, Bishop CC.Comparison of duplex imaging and arteriography in the evaluation of lowerlimb arteries Br J Surg 1998; 85: 1099±102

12 Velazquez OC, Baum RA, Carpenter JP Magnetic resonance angiography oflower-extremity arterial disease Surg Clin N Am 1998; 78: 519±37

13 Krans HMJ, Porta M, Keen H and Staehr Johansen K Diabetes Care and Research

in Europe: the St Vincent Declaration Action Programme Implementation Document,2nd edn Copenhagen: World Health Organization

14 Hood DB, Weaver FA, Papanicolaou G, Wadhwani A, Yellin AE Cardiacevaluation of the diabetic patient prior to peripheral vascular surgery Ann VascSurg 1996; 10: 330±5

15 Seeger JM, Self S, Harward TR, Flynn TC, Hawkins IF Jr Carbon dioxide gas as

an arterial contrast agent Ann Surg 1993; 217: 688±97

16 Mohan CR, Hoballah JJ, Martinasevic M et al Revascularization of theischemic diabetic foot using popliteal artery in¯ow Int Angiol 1996; 15: 138±43

17 Woel¯e KD, Lange G, Mayer H, Bruijnen H, Loeprecht H Distal vein graftreconstruction for isolated tibioperoneal vessel occlusive disease in diabeticswith critical foot ischaemiaÐdoes it work? Eur J Vasc Surg 1993; 7: 409±13

18 Stonebridge PA, Tsoukas AI, Pomposelli FB Jr et al Popliteal-to-distal bypassgrafts for limb salvage in diabetics Eur J Vasc Surg 1991; 5: 265±9.

19 Pomposelli FB Jr, Jepsen SJ, Gibbons GW et al A ¯exible approach toinfrapopliteal vein grafts in patients with diabetes mellitus Arch Surg 1991; 126:724±9

20 O'Mara CS, Flinn WR, Neiman HL, Bergan JJ, Yao JS Correlation of footarterial anatomy with early tibial bypass patency Surg 1981; 89: 743±52

21 Williams MR, Mikulin T, Lemberger J, Hopkinson BR, Makin GS Five yearexperience using PTFE vascular grafts for lower limb ischaemia Ann R Coll SurgEngl 1985; 67: 152±5

22 Berridge DC, al-Kutoubi A, Mans®eld AO, Nicolaides AN, Wolfe JH.Thrombolysis in arterial graft thrombosis Eur J Vasc Endovasc Surg 1995; 9:129±32

23 Moody P, Gould DA, Harris PL Vein graft surveillance improves patency infemoro-popliteal bypass Eur J Vasc Surg 1990; 4: 117±21

24 Bergamini TM, George SMJ, Massey HT et al Intensive surveillance offemoropopliteal±tibial autogenous vein bypasses improves long-term graftpatency and limb salvage Ann Surg 1995; 221: 507±15

25 Kwolek CJ, Pomposelli FB, Tannenbaum GA et al Peripheral vascular bypass

in juvenile-onset diabetes mellitus: are aggressive revascularization attemptsjusti®ed? J Vasc Surg 1992; 15: 394±400: discussion, 400 et seq

26 Tannenbaum GA, Pomposelli FB Jr, Marcaccio EJ et al Safety of vein bypassgrafting to the dorsal pedal artery in diabetic patients with foot infections J VascSurg 1992; 15: 982±90

27 Isaksson L, Lundgren F Vein bypass surgery to the foot in patients withdiabetes and critical ischaemia Br J Surg 1994; 81: 517±20

28 Pomposelli FB Jr, Marcaccio EJ, Gibbons GW et al Dorsalis pedis arterialbypass: durable limb salvage for foot ischemia in patients with diabetes mellitus

J Vasc Surg 1995; 21: 375±84

29 Pomposelli FB Jr, Jepsen SJ, Gibbons GW et al Ef®cacy of the dorsal pedalbypass for limb salvage in diabetic patients: short-term observations J Vasc Surg1990; 11: 745±51: discussion, 751±2

30 Quinones-Baldrich WJ, Colburn MD, Ahn SS, Gelabert HA, Moore WS Verydistal bypass for salvage of the severely ischemic extremity Am J Surg 1993; 166:117±23: discussion, 123

31 Rosenblatt MS, Quist WC, Sidawy AN, Paniszyn CC, LoGerfo FW Results ofvein graft reconstruction of the lower extremity in diabetic and nondiabeticpatients Surg Gynecol Obstet 1990; 171: 331±5

32 Karacagil S, Almgren B, Bowald S, Bergqvist D Comparative analysis ofpatency, limb salvage and survival in diabetic and non-diabetic patientsundergoing infrainguinal bypass surgery Diabet Med 1995; 12: 537±41

33 Panayiotopoulos YP, Tyrrell MR, Arnold FJ, Korzon-Burakowska A, Amiel SA,Taylor PR Results and cost analysis of distal (crural/pedal) arterialrevascularization for limb salvage in diabetic and non-diabetic patients DiabetMed 1997; 14: 214±20

34 Mashiah A, Soroker D, Pasik S, Mashiah T Phenol lumbar sympathetic block

in diabetic lower limb ischemia J Cardiovasc Risk 1995; 2: 467±9

17 Charcot Foot: an Update on

Pathogenesis and Management

ROBERT G FRYKBERGDes Moines University, Des Moines IA, USA

Neuro-arthropathywas ®rst described in 1868 byJ.-M Charcot1 and issometimes called a Charcot joint or Charcot foot Our current understanding ofthe pathogenesis and management of this condition has been enhanced byseveral keypapers and thorough reviews of the subject over the previous threedecades2±7 Although there has been an ultimate consolidation of purportedaetiologic theories of neuro-arthropathic joints, a review of past and presentliterature reveals that there have been no novel changes in our approach to thisdisorder since the earlyclassic works However, the past 20 years have broughtwidespread attention to the diabetic neuro-arthropathic foot, and the reportedincrease in frequencyof this condition maybe due primarilyto increaseddetection Neuro-arthropathyis now recognized as an important complication

of long-standing diabetes and peripheral neuropathyand is generallyacknowledged as a predisposing risk factor for foot ulceration and subsequentamputation7,8 Manyof these consequences can be averted through earlydetection of the acute neuro-arthropathic foot, a thorough understanding of itspathophysiology and a rational approach to management

NATURAL HISTORY AND PATHOGENESIS

Much of the current understanding of the aetiopathogenesis of the arthropathic foot is based on clinical observation and case studies There areThe Foot in Diabetes, 3rd edn Edited byA J M Boulton, H Connor and P R Cavanagh.

neuro-& 2000 John Wileyneuro-& Sons, Ltd.

Copyright  2000 John Wiley & Sons, Inc ISBNs: 0-471-48974-3 (Hardback); 0-470-84639-9 (Electronic)

still few, if any, prospective observational studies that have systematicallyexamined the varietyof putative casual factors Thus, much of the followingdiscussion is based on authoritative opinion.

Neuro-arthropathycan be de®ned as a relatively painless, progressive anddestructive arthropathyin single or multiple joints due to underlyingneurologic de®cits Peripheral joints are most often affected, althoughinvolvement of the spine can occur The location of the affected joint isdependent upon the nature of the disease causing the underlyingneuropathy7 Manydiseases can cause neuro-arthropathy, includingtertiarysyphilis (as Charcot originallydescribed), diabetes mellitus,syringomyelia and leprosy (Hansen's disease) (Table 17.1) With thiscentury's decline in frequency of patients with tabes dorsalis and theconcomitant rise in numbers of persons with diabetes, the latter has becomethe most frequent cause of neuro-arthropathy Certain diseases also have apredilection for speci®c sites of involvement Tabes dorsalis, for instance,usuallypresents as a monoarticular involvement of large joints of the lowerextremities such as the hip or knee Conversely, syringomyelia involves thejoints of the upper extremities, i.e the shoulder, elbow and cervicalvertebrae In diabetes mellitus, the joints of the foot and ankle arecharacteristicallyinvolved

Although some have postulated an intrinsic osseous defect in theneuropathic extremity, there have been no conclusive studies indicating aprimarydefect other than a relative osteopenia due to autonomicneuropathy9±12 It is likelythat the pathogenesis of the neuro-arthropathicfoot maybe directlyattributed to neuropathyand trauma The neuropathiccomponent consists of the classic sensorimotor polyneuropathy of diabetesinvolving both sensoryand motor nerves3,7,8 There is some loss of peripheralsensation, which results in absent or diminished pain, vibratorysensation,proprioception and temperature perception Additionally, the autonomicperipheral nerves are impaired, resulting in a ``sympathetic failure'' andattendant bone arteriovenous shunting, hypervascularity and demineraliza-tion10,12 The insensitivityof the distal extremityand the putative weakening

of bone due to the neurallyinitiated ``vascular re¯ex'' place the foot at risk forinjuryand subsequent development of neuro-arthropathy

Table 17.1 Diseases with potential for causing neuro-arthropathic joints

Diabetes mellitus Congenital insensitivityto pain

Tertiary syphilis Hysterical insensitivity to pain

Leprosy(Hansen's disease) Paraplegia

Syringomyelia Familial dysautonomia

Myelodysplasia Peripheral nerve lesions

Pernicious anaemia Spinal cord injuries

Multiple sclerosis

When extrinsic trauma occurs, such as a trivial twisting or blunt injury,the osteopenic bone is ostensiblymore likelyto fracture (although this hasnot been studied prospectively) Absence of the protective sense of painallows continued weightbearing on the injured foot, with consequenthyperaemic and in¯ammatory response to injury, resulting in increasedblood ¯ow and massive oedema The insensitive joints are subjected to theirextreme ranges of motion as capsular and ligamentous stretching or tearingresult from the primaryinsult and subsequent joint effusions Instabilityincreases as weightbearing continues, with progressive joint laxityandeventual subluxation, even in the absence of a primaryfracture Dislocatedarticular surfaces grind on adjacent bone, causing osteochondral fragmenta-tion and severe degeneration of joint architecture The hypervascularresponse to injurypromotes even more softening and resorption of bone.Further trauma (weightbearing) to these osteoporotic areas producesfurther destruction of the compromised joint, and a vicious cycle ensues.(Figure 17.1)

Often, an intra-articular or extra-articular fracture initiates the destructiveprocess Additionally, amputation of the great toe, often a consequence ofosteomyelitis or gangrene, may lead to neuropathic joint changes in theadjacent lesser metatarsal±phalangeal joints (Figure 17.2) Presumably, this

is a stress-related factor secondaryto an acquired biomechanicalde®ciency13 Since intra-articular infections can also be implicated in thepathogenesis of neuro-arthropathy, it becomes apparent that any type ofinjuryor in¯ammatoryprocess introduced to a neuropathic joint has thepotential for producing a neuro-arthropathic joint3

Neuropathy

Long-standing

diabetes

Neuropathic disease

Injury, sprain or fracture

Acute Charcot joint

Continued weightbearing

Figure 17.1 Pathogenesis of the neuro-arthropathic (Charcot) foot

Eichenholtz14 has divided the disease process into three stages based onpathologic ®ndings The stage of development is characterized bythe acutedestruction of the joint, with debris formation, osteochondral fragmenta-tion, capsular distention, ligamentous laxityand subluxation The stage ofcoalescence is marked byabsorption of much of the debris and fusion offragments to adjacent bone Finally, the stage of reconstruction involves theremodelling of bone ends and fragments This results in a lessening of thesclerosis and an attempt to restore joint architecture Clinically, it is easier toseparate the natural historyof neuro-arthropathyinto onlytwo stages: acute

or chronic These distinctions will also facilitate and direct treatment7,15 Theacute stage represents the active or destructive phase of the disease process,during which the joint is being activelydestroyed This would be consistentwith Eichenholtz's ``stage of development'' The chronic (quiescent) stageFigure 17.2 Osteolysis following great toe amputation