WIXLIB

Charcot Foot: Clinical Clues, DiagnosticStrategies, and Treatment PrinciplesValerie S. Marmolejo, DPM, University Place, WashingtonJonathan F. Arnold, MD, Great River Wound and Hyperbaric Medicine Clinic, West Burlington, IowaMario Ponticello, DPM, and Charles A. Andersen, MD, Madigan Army Medical Center, Tacoma, WashingtonAcute Charcot neuroarthropathy of the foot and ankle is often difficult to diagnose because of limited findings in the patient history, physical examination, imaging, and laboratory studies. Delay intreatment results in the development of rigid foot and ankle deformities, increasing the risk of ulceration, infection, and major lower extremity amputation. Acute Charcot neuroarthropathy should besuspected in any patient 40 years or older with obesity and peripheral neuropathy who presents withan acutely swollen foot following minimal or no recalled trauma and who reports minimal to no pain,particularly if radiography and laboratory markers of infection are normal. Magnetic resonance imaging or computed tomography should be performed in these cases. If changes consistent with acuteCharcot neuroarthropathy are observed, prompt immobilization and/or referral to a foot and anklesubspecialist is needed to minimize sequelae. Immobilization should continue until lower extremityedema and warmth resolve, and serial radiography shows evidence of osseous consolidation. Intranasal calcitonin salmon may have a role as adjunctive therapy. Although controversial, surgery may beindicated if there is severe dislocation or instability, concern for skin breakdown, or failure of conservative treatment to obtain a stable, plantigrade foot. (Am Fam Physician. 2018;97(9):594-599. Copyright 2018 American Academy of Family Physicians.)Charcot neuroarthropathy of the foot and experiencing a first episode. Consideration ofankle is an inflammatory condition affectingthe periarticular soft tissues and bone in personswith peripheral neuropathy, resulting in osseous subluxation, dislocation, and fracture, if thelower extremity is not immobilized.1 One in fourcases of acute Charcot foot is misdiagnosed, mostoften as cellulitis, gout, deep venous thrombosis,or a minor sprain2-13 (Table 1 2-8,14-16), which delaysdiagnosis by an average of seven months.2,17-19Without prompt treatment, the condition oftenresults in development of rigid foot deformities(i.e., the classic rocker-bottom foot [Figure 120]),increasing the risk of major lower extremityamputation by 15- to 40-fold.6This article reviews key elements of the historyand physical examination, imaging, and laboratory studies that can increase clinical suspicionfor acute Charcot neuroarthropathy in patientsCME This clinical content conforms to AAFP criteria forcontinuing medical education (CME). See CME Quiz onpage 565.Author disclosure: No relevant financial affiliations.these elements can assist with early and accuratediagnosis. Prompt initiation of lower extremity immobilization, with referral to a foot andankle subspecialist as needed, can minimize thesequelae (e.g., rigid foot deformity, ulceration,infection, amputation) and improve patients’quality of life.2-6,8-11,14,17,20-29HistoryThe diagnosis of acute Charcot neuroarthropathy should be considered in any patient 40 yearsor older with obesity and peripheral neuropathywho presents with a unilateral swollen limb andminimal or no associated pain.2-12,14,18-20,22-25,29-37Diabetes mellitus is the most common cause ofperipheral neuropathy in the United States. Thelifetime prevalence of Charcot neuroarthropathyin patients with diabetes ranges from 0.1% to 10%,increasing to 29% to 35% if peripheral neuropathyis present.2,3,12,24-26,30,38,39 Compared with those whohave type 2 diabetes, patients with type 1 diabetestend to have diabetes for a longer duration (24 8.4 years vs. 13 8.1 years) and be younger (42 10.2 years vs. 59 7.8 years) when acute CharcotDownloadedfrom theAmericanFamily Physician website at www.aafp.org/afp.Copyright 2018 American Academy of FamilyPhysicians.For the9private, pVolume97, Number1, 2018mercial use of one individual user of the website. All other rights reserved. Contact copyrights@aafp.org for copyright questions and/or permission requests.

CHARCOT FOOTSORT: KEY RECOMMENDATIONS FOR PRACTICEEvidenceratingClinical recommendationReferencesIn patients with suspected acute Charcot neuroarthropathy, early and accurate diagnosis andprompt immobilization reduce the incidence of rigid foot deformity development, whichincreases patient quality of life and reduces the risk of ulceration, infection, and amputation.C2-6, 8-11, 14,17, 20-29The diagnosis of acute Charcot neuroarthropathy should be considered in any patient 40 yearsor older with obesity and peripheral neuropathy who presents with a unilateral swollen limband minimal or no associated pain.C2-12, 14,18-20, 22-25,29-37Acute Charcot neuroarthropathy should be considered in patients with recurrent cellulitis butno systemic or laboratory findings concerning for infection.C2-14, 22, 30,38, 42Bilateral weight-bearing radiography is recommended to allow for comparison between bothfeet in persons with suspected acute Charcot neuroarthropathy. Clinicians should look for signsof subtle subluxations or ligamentous avulsion, which denote impeding osseous instability.C2-4, 9-12, 14,20, 22-26,30, 38, 39A consistent, good-quality patient-oriented evidence; B inconsistent or limited-quality patient-oriented evidence; C consensus, diseaseoriented evidence, usual practice, expert opinion, or case series. For information about the SORT evidence rating system, go to http://www.aafp.org/afpsort.TABLE 1FIGURE 1Common Misdiagnoses of Acute ellulitisErysipelasAcute inflammatory arthritisDeep venousthrombosisOsteomyelitisGoutFractureSeptic arthritisPlantar enous insufficiencyInformation from references 2 through 8, and 14 through 16.neuroarthropathy develops.6,31 Patients with type 1 diabetesalso tend to be less obese and more prone to recurrent eventsof Charcot neuroarthropathy than patients with type 2 diabetes.32 An A1C level greater than 9% is associated with a 30%increased risk of developing Charcot neuroarthropathy.31Misdiagnosis of acute Charcot neuroarthropathy mayoccur when it presents in patients who have peripheralneuropathy from etiologies other than diabetes, such asalcoholism, use of chemotherapeutic agents, inherited disorders, or trauma.34 Other factors that increase the risk ofacute Charcot neuroarthropathy include a history of footulceration; retinopathy; nephropathy, renal failure, or renaltransplantation; rheumatoid arthritis; iron deficiency anemia; or obesity.6,12,31 Between 25% and 50% of patients recallno trauma or inciting event, and the same number do notreport pain.2,5-10,14,17-20,22,23,39 If an inciting event is recalled, itis often minor, such as walking a long distance or sustaining a minor sprain. Patients who recall an inciting event areMay 1, 2018 Volume 97, Number 9Classic rocker-bottom foot associated with untreatedCharcot neuroarthropathy.Reprinted with permission from Sommer TC, Lee TH. Charcotfoot: the diagnostic dilemma [published correction appears inAm Fam Physician. 2002;65(12):2436-2438]. Am Fam Physician.2001;64(9):1593.more likely to report pain, often described as a constant discomfort not severe enough to stop ambulation.5,9,12Physical Examination and Laboratory StudiesPatients with acute Charcot neuroarthropathy are usuallyafebrile with normal vital signs. More than 70% of the time,patients have unilateral lower extremity edema (Figure 2)with associated erythema and increased warmth (2 C to8 C [3.6 F to 14.4 F]) with no open wound.2,4,10,11,14,17,18,20-22,39Peripheral neuropathy can be confirmed with use of aSemmes-Weinstein monofilament test. Deep tendon reflexesare also severely impaired, particularly the Achilles tendonreflex.6 Lower extremity edema extends down to the foot,which is particularly swollen around the affected joints.14www.aafp.org/afp American Family Physician 595

CHARCOT FOOTFIGURE 2ABExamples of increased edema of the left lower extremity compared withthe right secondary to acute Charcot neuroarthropathy (A and B).FIGURE 3ABPatients with these findings may havebeen previously treated for cellulitis.Acute Charcot foot should be considered in patients with recurrent cellulitisbut no systemic or laboratory findingsconcerning for infection.2-14,22,30,31,38Antibiotic therapy does not resolvesymptoms, which may have led to previous hospital admission. Symptomresolution may occur during hospitalization because patients spend moretime in bed; however, symptoms mayreturn after discharge when patientsare ambulatory, which may lead to amisdiagnosis of recurrent cellulitis.Although acute Charcot neuroarthropathy can coexist with cellulitis,osteomyelitis, or open wounds of thelower extremity, the latter two are morecommon with recurrent episodes.Imaging StudiesVENOUS DUPLEXULTRASONOGRAPHYVenous duplex ultrasonography maybe performed when deep venousthrombosis is suspected. Resultsshould be normal in acute Charcotneuroarthropathy.RADIOGRAPHYRadiography should be the primaryimaging study. Although the characteristic bony destruction of Charcotneuroarthropathy can take six to 12months to become visible on radiography, initial imaging serves as a baseline and allows fordetection of subtle changes denoting instability. Subtle subluxations and small flecks of bone secondary to ligamentousavulsion fractures may be present, signaling instability andimpending osseous destruction2-4,9-12,14,17,20-26,30,38,39 (Figures3 and 4). More than 60% of all Charcot neuroarthropathyevents affect the midfoot.12,24 Osseous overlap in the midfoot can make subtle subluxations and minimally displacedfractures difficult to visualize.41-43 For this reason, bilateralweight-bearing radiography is recommended for comparison of both feet.2,3,17,20,21Compared with the right foot (A), bilateral foot radiography revealsincreased soft tissue volume and irregularities about the tarsometatarsaljoint of the left foot (B) secondary to acute Charcot neuroarthropathy.Pedal pulses are most often palpable and can be describedas bounding if unobscured by edema.6 The increase in skintemperature can assist in diagnosis and resolution of theCharcot process.35 Less expensive, industrial-grade, noncontact infrared thermometers have been shown to be as reliable in detecting temperature of the skin as a more expensivemedical infrared thermometer.36Erythema secondary to the inflammation of acute Charcotneuroarthropathy can be differentiated from infection byelevating the affected extremity above the level of the heartfor five to 10 minutes. Erythema secondary to acute Charcot neuroarthropathy will dissipate, whereas erythema frominfection will not.13 Laboratory markers of infection, such aswhite blood cell count, C-reactive protein level, and erythrocyte sedimentation rate, are usually normal.11,12,14,17,25,38,40596 American Family PhysicianMAGNETIC RESONANCE IMAGINGMagnetic resonance imaging (MRI) in the acute phase ofCharcot neuroarthropathy can demonstrate periarticularwww.aafp.org/afp Volume 97, Number 9 May 1, 2018