Diabetes-Related Foot Pathology

High morbidity Lifetime ulcer risk for diabetics 25% Nearly all diabetes-related foot infection

secondary from ulcer

Nothing To Disclosure

MRI Sensitivity & Specificity Osteomyelitis of Diabetic Feet

1995 (no Gd): 82% sensitivity, 80% specificity 1997 (with Gd): 90% sensitivity, 70% specificity

no effect of Gd (disputes earlier data)

2007 (no Gd): 90% senisitivity, 83% specificity

MRI Primary Findings

Marrow signal (HIGH STIR/T2 & LOW T1)* Gd Marrow enhancement

Ulcer or sinus tract leading to bone with abnormal

marrow signal Presence of abscess

MRI Secondary Signs

Cellulitis Foreign body Periosteal reacton

Osteomyelitis vs. Neuropathic Charcot

Marrow signal change

Single bone Diffuse infiltration Minimal deformity Ulcer, sinus tract, abscess Wgt. bearing: fore/hind

foot

Marrow signal change Multiple bones Periarticular &

subchondral Deformity with bone

debris Edema but intact skin Non-wgt. bearing:

midfoot

Osteomyelitis Neuropathic Charcot

Location, Location, Location

Neuroarthopathy (Charcot)--MIDFOOT: Tarsal-Tarsal Tarsometatarsal (TMT)

Osteomyelitis FORE & HINDFOOT: Distal to tarsometatarsal Calcaneus Malleoli

Distal phalangeal osteomyelitis

Low T1 signal

Distal phalangeal osteomyelitis

High T2 signal

Distal phalangeal osteomyelitis

Gd enhancement

Metatarsal head osteomyelitis with sinus tract

Forefoot osteomyelitis with contiguous abscess

Abscess and Osteomyelitis

20% of osteomyelitis are + for soft tissue abscess 100% correlation with osteomyelitis (same as sinus

tract) Abscess more common in post surgical foot 50% of all abscesses in fore foot and are directly

contiguous Mid/Hind foot abscess may be remote from site of

osteomyelitis

Calcaneus osteomyelitis with sinus tract and abscess

Osteomyelitis with intramedullary bone abscess of talus

Osteomyelitis: confluent, geographic medullary distribution

No osteomyelitis: Ulcer with minimal subcortical T1/T2 signal

Osteomyelitis: ulcer with confluent abnomal T1 signal

No osteomyelitis: T1 “hazy” pattern

No osteomyelitis: T1 reticulated pattern

Neuropathic arthropathy of midfoot

Neuropathic arthropathy of midfoot

Neuropathic arthropathy with superimposed osteomyelitis

Bone Biopsy

For histological proven osteomyelitis, positive rate of percutaneous biopsy: 50% 42% 34% (largest study)

Bone Biopsy

Aspiration of > 2cc’s purulent fluid—83% positive osteomyelitis rate.

Risk of seeding uninfected tissue. Utility of identifying an organism?