ERRATA (thank you to commenters):
Claw toe has dip flexion (not extension).

This is a flowchart on the diabetic foot, covering the etiology, pathophysiology, and manifestations.

ADDITIONAL TAGS:
Risk factors / SDOH
Cell / tissue damage
Structural factors
Medicine / iatrogenic
Infectious / microbial
Biochem. / metabolic
Immunology / inflammation
Signs / symptoms
Tests / imaging / labs
Environmental / exposure
Nervous system pathology
Flow physiology
Pathophysiology
Etiology
Manifestations
Diabetic foot
Foot ulcers: skin breakdown with possible surrounding
tissue necrosis
Diabetic foot ulcer, classified as …
Neuropathic ulcers
Neuroischemic ulcers
Ischemic ulcers
Peripheral sensory neuropathy
Autonomic neuropathy
Peripheral artery disease
Microvascular changes
Diabetes mellitus
Chronic hyperglycemia
Sorbitol accumulation in cells
Ulcers at sites of repetitive stress/trauma: bony abnormalities, bottom of foot (metatarsal bones or heel)
Ulcers on the toes or lateral foot
Usually painless
+/ sensory loss, motor weakness
+/ cool foot, no palpable pulses
Infection
Trauma
Calluses
↑ rates of …
Hospitalization
Amputation
Death
Skin and soft tissue infection
In ~50% of ulcers
Staphylococcus spp.
Streptococcus spp.
Typically polymicrobial
Most common causative pathogens:
Edema
Induration
Erythema 0.5 cm
Tenderness
Warmth
Purulent exudate
↓ cytokine production
Defects in phagocytosis
Immune cell dysfunction
Diabetes mellitus impairs immune system
Diabetic foot osteomyelitis
Ulcer overlying bony prominence, exposed bone
Ulcer size 2 cm2 and / or ulcer depth 3 mm
Chronic, treatmentresistant ulcer
Positive probetobone test
Markedly increased ESR (70 mm/hour)
Leukocytosis
↓ intrinsic muscle volume
Thickening of plantar aponeurosis
Bone destruction
Subluxation / dislocation
Gas gangrene
By Heather MurphyLavoie https://www.ncbi.nlm.nih.gov/books/NB..., CC BY 4.0, https://commons.wikimedia.org/w/index...
Hammer toe: PIP joint flexion; +/ DIP joint extension, +/ MTP joint hyperextension
Claw toe: PIP joint flexion, DIP joint extension, and MTP joint hyperextension
Inflammation: swelling, warmth, erythema
Diabetic neuropathic arthropathy (Charcot foot)
Mild to moderate pain
Midfoot collapse (rocker bottom foot deformity)
Osteolysis → fractures
Painless bony deformities