Perspectives in Circulation Today

Osteomyelitis and Cellulitis Revisited

Neuropathic Ulcers

Why are these legs lost? Would you have lost this foot?


The plantar skin under the lateral metatarsal heads was gone and the fat pad infected. Diffuse rubor on the dorsum of the foot that did not blanch on pressure pointed to extensive cellulitis. Angiology 48, Number 5, part 2: S35-S58, 1997.


The cellulitis tissue around the 5th toe had already dried and turned black while the entire dorsal aspect of the other metatarsals was threatened.

Neuropathic ulcer disease: Patient MM was a 46 year old women with type 1 diabetes mellitus that had been poorly controlled over 22 years. On the 8th of January, her podiatrist debrided an infected plantar callus beneath her 5th metatarsal head and started her on antibiotics and Epsom foot soaks. Her infection progressed over the next ten days leading to hospitalization on the vascular surgery service. She was begun on intravenous gentamicin and tetracycline with no effect on her fever (101 degrees F) or her leukocytosis (17.7 to 20.2). Her ulcer appeared to be enlarging and the possibility of leg amputation was considered. On the 4th hospital day a boot consultation was requested (pictures above). Hammer toes suggested the presence of her underlying neuropathy. Light touch and position sense were absent and 2-point discrimination was over 25 cm. Her antibiotics appeared to be appropriate according to her cultures. Our routine program for such patients was begun: (a) appropriate oral or intravenous antibiotics to prevent septic emboli, (b) a cleansing foot soak in dilute peroxide or Betadine to remove superficial pus and debris, (c) local antibiotic injections, here with gentamicin, into the necrotic areas under the 3rd-5th toes and into the top of the 3rd toe and the side of the 5th toe and (d) Mini-Boot therapy with the foot immersed in 200 ml multielectrolyte solution (Sea Soaks) and gentamicin (80 mg/half gallon). The local antibiotic injection were given once daily with an insulin syringe while the boot therapies in the antibiotic solution were given three to four times a day. She appeared to be responding but her boot doctor went on vacation for a week during which her therapy was again limited to intravenous antibiotics (the vascular surgeons declined the opportunity to administer the local antibiotic injections). Her fever returned and again her foot infection seemed to be progressing leading the surgeons to urge leg amputation. She refused insisting on waiting a week to restart boot therapy. The latter was restarted and her foot did well. Her left toe was left atrophied but she lost no parts and was discharged ambulatory to receive boot therapy as an outpatient,
Figure 4. Patient MM: By the end of May, her foot was healed. Her fifth toe was atrophied and had a small residual scab. New callus had formed at the pressure point under her fifth metatarsal head.
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Normal sympathetic tone keeps the AV shunts closed. Cholinergic nerves may
stimulate nitric oxide and prostacyclin increasing flow through the capillaries. Angiology 42: 767-778, 1991


Loss of sympathetic tone and the AV shunts open. Loss of cholinergic
stimulation results in diminished capillary flow. Associated ASO may diminish arterial flow further.


Comment: Patients with diabetic neuropathy are susceptible to necrotizing cellulitis in the absence of macrovascular disease. Denervation of the small muscles in the foot results in hammer toe deformities and abnormal pressure points. Sweating and reactive hyperemia may be absent due to loss of postganglionic cholinergic innervation. Loss of sympathetic innervation diverts arterial blood flow through A-V shunts. Fissures and cracks in dry skin and callus provide entry for bacteria. In the absence of pain sensation, the infection may be unappreciated. Elaboration of bacterial enzymes may digest the tissue and produce a chemical arteritis depriving the infected area of arterial blood with its immune factors and any administered antibiotics. Bypass procedures are useless in the presence of palpable pulses. Incision and drainage procedures are useless early in the process when only large reddened cellulitis areas may be present; later if abscesses develop such procedures are important. In this patient, the local injection of antibiotics delivered effective therapy when both oral and intravenous routes were ineffective. The therapy with the Mini-Boot both disseminated the antibiotic throughout the infected tissue and helped maintain and restore blood flow through the inflamed areas of the foot thus assisting the delivery of leukocytes and systematically administered antibiotics. Pumping the foot in the multielectrolyte solution containing antibiotics effectively scrubbed, cleaned and debrided the foot daily. No further sharp debridements were done and no large incisions that would require time and additional procedures to heal were made. Unfortunately, the patient relapsed when the daily local antibiotics injections were interrupted. The infection was again brought under control when they were resumed and continued until her lesions were obviously sterilized and healing under way. In this fashion, boot therapy may salvage many feet that appeared to be lost.

Factors Leading to Potential Limb Loss in This Patient and Others with Neuropathic Ulcers

Factor
Inadequate level of antibiotic at site of infection
Failure of patient and physician to appreciate severity of infection.
Delay by both/either patient or physician... Wait and see approach.
Physician ignorance regarding the potential benefits of local antibiotic therapies... and their tendency, if they do use local injections, to do so intermittently rather than daily and aggressively.
Widespread misbelief that osteomyelitis requires surgical removal of infected bone. The surgical procedure enlargening the wound.
The failure of some insurance companies and Medicare regions to reimburse physicians for the salvage procedures described above (which commonly can be performed in the outpatient clinic) while reimbursing more expensive ablative and invasive procedures which in patients like the one above either prove ineffective or inappropriate.

Volume 3, Number 1

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