By: G. Blaine Bishop, Jr., MD
The Centers for Disease Control estimates there are 25.8 million diabetic American as of 2011, with 1.9 million new cases being diagnosed annually. Medicare FFS data from 2008 showed diabetic foot ulcers in these patients. 20-25% of these patients went on to some form of amputation (toe, foot, or leg). “Up to 83% of lower limb amputations in diabetic patients are preceded by foot ulcers that fail to heal.”
Sadly, the 5 year death rate on a diabetic patient following a below-the-knee amputation is 47%! (In contrast, only 28% of Stage III breast cancer patients die within 5 years – American Cancer Society.) Both the in-hospital and in-home healthcare costs skyrocket after a major amputation. Surprisingly, virtually all insurers are willing to invest significant monies in order to heal diabetic foot ulcers (DFU’s).
As most physicians are aware, chronically elevated glucose levels can lead to neuropathy, peripheral vascular disease, and impaired white blood cell function. It is estimated that 30-50% of diabetics will develop neuropathy in their feet. Unsurprisingly, 60% of DFU’s occur in patients with neuropathy only, 15-20% in diabetics with peripheral vascular disease, and 15-20% DFU patients with both neuropathy and peripheral capsular disease.
Rare is the physician who hasn’t see a foot ulcer in a diabetic patient whose poorly fitting shoe and lack of sensation have resulted in callus build up, followed by pressure necrosis, followed by infection. Cellulitis, deep space infections, and even osteomyelitis result all too commonly from this scenario. Frequently, a multidisciplinary team treating the many components of these lesions will be required. Such resources often exceed the office capabilities of our hard working primary care physicians.
The initial patient encounter in a dedicated wound care center (WCC) involves wound measurement, evaluation of blood sugar control, assessment of arterial blood inflow/wound tissue oxygenation, evaluation for infection, as well as determining the correction of the cause of the chronic foot trauma. Typical initial treatments involve off-loading the ulcer (total contact cast, walking boot, temporary diabetic shoe, and –ultimately- a custom designed orthotic shoe insert to prevent further ulcers). Regular wound debridement that rids the ulcer of callus, dead tissue, and the bacteria-laden biofilm which so often covers the surface of the ulcers. A specialized wound dressing helps provide enough moisture to promote healing but not so much as to cause wound maceration.
When these primary therapies aren’t enough (i.e. the wound is less than 40% healed after 4 weeks of these initial treatments), more advanced therapies are indicated.
Many physicians are familiar with the Wound VAC wound closure system. Some may not be as familiar with topical vascular endothelial and human platelet derived growth factors. Also human “skin substitutes” from tissue cultured neo-natal foreskin contain a number of growth factors which stimulate ingrowth of the patients own skin calls in order to heal the wound.
Revascularization via stenting or leg artery bypass can improve oxygen delivery to the wound when peripheral vascular disease is an issue. Hyperbaric oxygen is another advanced therapy to improve DFU oxygen level. 100% oxygen under 2 atmospheres of pressure for 90 minutes at a time is demonstrated to 1) kill bacteria (even osteomyelitis), 2) stimulate the growth of new arterioles into the ulcer, and 3) stimulate the proliferation of wound healing cells. Thus, according to the American Diabetic Association, examples of wound patients who should be referred to a Wound Care Center include:
1) A wound that had failed to show significant progress after 4 weeks of standard care
2) A wound that involves deep tissue structures or is limb-threatening
3) A wound complicated by significant comorbidities including peripheral vascular disease, vascular disease, persistent edema, persistent infection, or prior radiation to the area
1) Bowering; Canadian Family Physician
Vol 47, May 2001 : 1007-16
2) ADA Consensus Development Conference On Diabetic Foot Wound Care
- Diabetes Care 22(8) 1345-60, 1999
G. Blaine Bishop, Jr., MD
Advanced Surgeons, PC
Member of the Medical Staff – Trinity Medical Center