DIABETIC FOOT DISEASE

See also Pressure Ulcers for discussion of non-diabetic pressure ulcers

I. Foot ulcers, infections, and other foot problems are a major cause of morbidity (including amputations) and mortality in DM and are probably due to the dual effects of neuropathy (decreasing pt's awareness of early foot problems, e.g. minor trauma) and ischemia (leading to poor healing and infection).

II. Risk factors for foot ulcers in pts with DM:

• Loss of "protective sensation"
• Vascular disease
• Skin or nail abnormalities
• Previous ulcers or amputations

III. Prevention of foot ulcers in high-risk patients, per ADA 1998:

• Education inc. daily self-care, avoidance of foot trauma, actions to take if problems develop
• Professional nail and callus care
• Appropriate footware (athletic shoe or "shoe of similar design," e.g. with soft insoles and adequate depth)

IV. In DM foot ulcers, it is important to determine whether there is infection present, particularly Osteomyelitis.  Such infections are commonly polymicrobial and usually require broad-spectrum abx, at least initially.  Predictors of & diagnostic modalities for osteomyelitis in DM foot infections (Clin. Inf. Dis. 25:1318, 1997--rvw;AFP):

• Wound present > 2wks
• Ulcer area > 2 square cm
• Depth > 3mm
• Positive "probe to bone" test--can contact bone when probing ulcer
• ESR > 100 mm/h
• Plain x-rays only after 10-20d of bone infection
• 3-phase bone scan (sensitivity about 86%; specificity only about 45%)
• Indium-111-tagged WBC scan (highly specific)
• MRI is highly specific but some false-positives can occur, particularly in presence of asteoarthropathy
• Gold standard is bone biopsy (concordance between bone bx culture and cultures of swabs of the ulcer are poor; only 23% in one study--Clin. Inf. Dis. 42:57, 2006--JW)

• As of 1999, radiolabelled monoclonal Ab's against granulocyte Ag's, e.g. "sulesomab" may help identify osteomyelitis complicating diabetic foot ulcers--more sensitive but less specific than labelled WBC scanning or bone scan in one study (Clin. Inf. Dis. 28:1200, 1999--JW)

V. Management of DM foot ulcers:

• Consider possibility of infection
• Debride infected tissue and I & D abcesses as needed
• Minimize weight bearing on the ulcer (crutches, bedrest, total-contact casts, special shoes, etc.)
• Consider vascular reconstruction if appropriate
• Maintain glycemic control
• Address any nutritional deficiencies
• Electrical stimulation may aid healing
  • 27 pts with LE ulcer(s) x > 3mos (from DM, arterial insufficiency, or venous insufficiency) randomized to high-voltage pulsed current therapy 3x/wk x 4wks vs. sham tx.  Over 4wks, sig. greater reductions in wound size seen in active tx group (44% vs. 16%) (Phys Ther. 2003;83:17-28)
• Platelet-derived Growth Factor, recombinant, 0.01% gel (Becaplermin, brand name Regranex):

1. Use: apply 1/16-inch thick continuous layer of gel daily to ulcer base and cover wound w/saline-moistenet dressing. After 12h, rince off the gel and re-cover the wound.
2. Higher healing rates c/w placebo in 2 randomized trials w/total 500 pts treated x 20wks (Med. Lett. 40:73, 1998)
3. No adverse effects identified

• Topical Retinoids
  1. In a study in 24 pts with diabetic foot ulcers but no evidence of peripheral arterial disease or infection randomized to tretinoin 0.05% applied to ulcer 10min/d followed by saline rinse vs. placebo x 4wks; all wounds had Iodosorb iodine gel applied between treatments.  After 16wks, active-tx group had sig. greater decrease in size of ulcers and sig. higher incidence of complete ulcer healing (45% vs. 18%) (Arch. Dermatol. 141:1373, 2005--JW)

VI. Management of infected DM foot ulcers: