Diabetic Foot Charcot Neuropathy

Question 1

What is Charcot foot?

Answer 1

• A CHRONIC AND PROGRESSIVE JOINT DISEASE after LOSS OF PROGRESSIVE SENSATION

Question 2

What does charcot foot lead too?

Answer 2

• Destruction of joints and surrounding bony structures
• May require Amputation if left untreated

Question 3

What is the epidemiology of Charcot foot?

Answer 3

• 0.1-1.4% of pt w diabetes
• 7.5% with diabetes and neuropathy
• Presents type 1 DM age 5th decade ( 20yrs from DX)
• Present type 2 - in 6th decade ( 5-10 yrs from DX)

location

• Foot and ankle
  
  • 9-35% bilateral disease
• Shoulder and elbow
• knee

Question 4

Which joints does Charcot effect?

Answer 4

• Foot and ankle 9-35% have bilat disease
• Shoulder and elbow
• Knee -> ligamentous laxity

Question 5

What are the risk factors for Charcot ?

Answer 5

• Diabetic Neuropathy
• xs ETOH
• Leprosy
• Myelomeningogcele
• Tabes Dorsalis/Syphilis
• Syringomyelia

Question 6

What is the pathophysiology of Charcot?

Answer 6

• NEUROTRAUMATIC
  
  • • insensate joint subjected to REPETITIVE MICRO TRAUMA
  • body unable to adopt mechanism to protect due to abnormal sensation
• NEUROVASCULAR
  
  • ​autonomic dysfunction increases blood flow thru Av shunting -> bone absorption and weakness
  • ? INFLAMMATORY CYTOKINES IL10, TNF ALPHA
  • lead to increased production of transcription factorKB, rank/rankl/opg triad pathway

Question 7

Do you know any classifications?

Answer 7

• EICHENHOLTZ
• Stage O= Joint oedema, radiographs are negative, bone scan positive in all stages
• Stage 1 FRAGMENTATION= Joint oedema
  
  • ​radiographs= osseous fragementation with joint dislocation - see pic
• ​​​Stage 2= COALESCENCE
  
  • ​decrease bone oedema
  • xray- coalescence of fragments and absorption of bone debris
• Stage 3= RECONSTRUCTION
  
  • no local oedema
  • xray- consolidation & remodelling of fracture fragments

Question 8

What are the PC of someone with a charcot joint?

Answer 8

• Swollen foot and ankle
• PAIN 50%,
• PAINLESS 50%
• Loss of function

Question 9

What do you find on examination?

Answer 9

• Acute
  
  • Swollen
  • Warm
  • Erytherma- decrease with elevation cf infection
• Chronic
  
  • Structurally deformed foot
  • rocker bottom deformity- see pic
  • pes planus
  • bony prominence
  • Lack of sensation- semmes- weinstein testing

Question 10

What do you see on X-rays ?

Answer 10

• Acute- degenerative changes may mimic OA
• chronic-
  
  • ​obliterated joint space
  • Fragmentation of bony surface-> subluxation/dislocation
  • HERETROPHIC OSSIFICATION
  • scattered bone in soft tissue swelling

Question 11

Are bone scans helpful in charot ?

Answer 11

• Yes to identify presence of superimposed osteomyelitis
• Technetium- maybe positve for neuropathic joint and osteomyelitis
• Indium wc- cold neuropathic but hot for osteomyelitis

Question 12

Are MRI scans helpful?

Answer 12

• Yes identify abscess from soft tissue swelling

Question 13

Are biopsy useful in charot joints?

What investigations are also helpful?

Answer 13

• Yes
• Can guide antibiotic tx in cases of osteomyelitis or soft tissue abscess
• FBC/ESR- both elevated in infection/Charcot arthropathy

Question 14

What are the tx options for charcot arthropathy?

Answer 14

• TOTAL CONTACT CASTING- Cast changed 2-4 wks for 2-4 months
• Orthotics- charcot restraint walker boot used after contact casting
• SHOE WEAR MODIFICATIONS- double rocker reduce risk of ulceration
• Medication- bisphosphonates, topical anaesthetics, antidepressants
• Outcomes 75% success rate

Operative

• Resection of bony prominence (exostectomy) & TAL
  
  • ​Braceable foot w equinus deformity + focal bony prominenece= skin breakdown
  • Joint stability good
  • Aim achieve a plantigrade foot that allows ambulation
• Arthrodesis and osteotomies
  
  • ​severe defoemities, unstable joints that are non braceble
  • v high complx rate 70%
• Amputation
  
  • ​failed surgery, infection
  • goal is partial/limited amputation if vascularity allows

Question 15

Describe the surgical technique for arthrodesis in charcot foot?

Answer 15

• Fixation technique
  
  • Screws/plates & tibiocalcaneal nail
  • ex fix - bone quality poor
  • post op minimal weight bear 3 months
• High complication rate up tp 70%
  
  • Infection
  • hardwear malposition
  • recurrent ulceration
  • fracture

Question 16

What is epidemiology of diabetic foot ulcers?

Answer 16

• 12% of diabetics have foot ulcers
• most common medical complication causing diabetics to seek medical attention
• Responsible for 85% of lower extremity amputations

Question 17

What are the risk factors fo diabetic foot ulcers?

What are the varibles predictive of poor healing in daibetic foot ulcers?

Answer 17

• Factors associated with decreased healing potential
  
  • Uncontrolled Hyperglycaemia
  • inability to offload the affected area
  • poor circulation
  • infection
  • poor nutrition
    *

Question 18

Name the factors associated with increased healing potential?

Answer 18

• Serum albumin >3.0g/L
• Total lymphoycte count >1,500/mm3

Question 19

What are the varibles predictive of poor healing in daibetic foot ulcers?

Answer 19

• Transcutanous o2 pressure <20mmHg
• Ankle brachial pressure index <0.45
• Albumin <3.0g/L
• Total lyphocytes <1,500/mm3

Question 20

What is the pathophysiology of diabetic foot ulcers?

Answer 20

• Neuropathy
  
  • largest effect
  • sensory dysfunction-> lack of protective sensation-> ulcer
  • autonomic dysfunction-> drying of skin due to lack of normal glandular function
  • increased mechanical & axial stress on skin more prone to injury due to drying
• Angiopathy
  
  • Iesser effect than neuropathy
  • >60% of diabetic ulcers have decreased blood flow due to peripheral vascular disease

Question 21

Name any associated conditions of diabetic foot neuropathy?

Answer 21

• Infection/Osteomyelitis
• High rates of osteomyelitis 67% if bone is probed or exposed at base of ulcer
• organisms
  
  • Usually polymicrobal
  • gram positive- aerobic gram positive cocci- s. aureus- STAPH AUREUS
  • gram negative- found in chronic wounds
  • Anerobes- obligate pathogens with ischaemia/gangrene

Question 22

Can you name and decribe a classification system of diabetic foot ulcers?

Answer 22

• Wagner
• Grade 0 - skin intact but bony deformities leads to foot at risk
  
  • shoe modification with serial exams
• Grade 1- superificial ulcer
  
  • office debridment and contact casting
• Grade 2- deeper , full thickness extension
  
  • Operative formal debridment and contact casting
• Grade 3- Deep abscess formation/oseomyelitis
  
  • Operative formal debridment & contact casting
• Grade 4- Partial Gangrene of forefoot
  
  • Local vs larger amputation
• Grade 5- Extensive gangrene
  
  • Amputation

Question 23

What are the symptoms and signs of diabetic foot ulcer?

Answer 23

Symptoms

• Often painless- unable to feel Semmes- weinstein monofilament 5.07

Signs

• Depth of ulcer- probe
• presence of infection- cellulitis, pus, gangrene
• excess achilles tendon tightness- exacerbate ulcers by fixed plantarlexion
  
  • Silverskold test-
  • improved ankle dorsiflexion with knee flexion= Gastronemius tightness
  • equivalent ankle dorsiflexion wiht knee flexion/extension = achilles tight
• Acess circulation

Question 24

What studies may add you in daignosis of diabetic foot ulcer?

Answer 24

• If no peripheral pulses
• Transcutanous oxygen pressure TcpO2
  
  • consider gold standard to assess wound healing potential
  • >30mmHG or 40mmhg is good sign healing
• ​ABIs
  
  • ​calcification in vessels-> inaccurate reading
  • elevates the ABI due to decreased compliance of calcifiec vessels
  • index of 0.45 & toe pressure >40mmHg are needed to heal an ulcer

Question 25

What imaging may be of assisting in diabetic foot ulcers?

Answer 25

• Xrays
  
  • AP, lateral , oblique of foot and ankle
• MRI
  
  • best in differentiatinb abscess from soft tissue swelling
  • difficult to differentiate infection from Charcot arthropathy on MRI
• Bone Scan
  
  • Tc99m
  • useful to ddx soft tissue, infection and charcot arthopathy

Question 26

What is the tx of diabetic foot ulcers?

Answer 26

Factors to consider-

• angiopathic vs neuropathic
• Deep vs superifical
• osteomyelitis
• pyarthrosis

Non operative

• Shoe modification
  
  • Deep wide shoes, custom insoles, rocker bottom soles ( reduced plantar pressure on foot)
• Wound care
  
  • provide moist environment, absorb excudate, act as barrier, off load pressure on ulcer
• Total Contact Casting
  
  • Gold standard for mechanical relief plantar ulceration
  • CI= infection, marginal arterial supply to area, pt unbel to comply / tolerate cast
  • ulcers reoccur 3-4 weeks post cast removal
• Antibiotics tailored to bone biopsy culture results if osteomyelitis

Operative

• Surgical debridment, antibiotics , local wound care, total contact casting
  
  • grade 3 or > undergo I&D w antibiotic tx before casting
  • TTC for 4 months then charcot retraint walker then custom shoe.
• Osteotomy +/- TAL
  
  • bony prominence -> internal pressure
• Partial Calcanectomy +/- TAL
  
  • ​Large heel ulcers w assoc calcaneal Ostemyelitis
  • preserves limb length & decrease morbdity cf higher level amputations
• Syme amputation
  
  • ​I= forefoot gangrene & palpable post tibial artery pulse

Question 27

What does a syme amputation include?

Answer 27

• Ankle disarticulation
• removal of malleoli
• anchoring heel pad to weight bearing surface- must have a viable heel pad- branches of posteriot tibial artery= NB important palpable POST TIBIAL PULSE