More from Frykberg's High Risk Foot Clinic

Robert Frykberg DPM, MPH PRESENT RI Editor Diabetic Limb Salvage

Just when you think you’ve achieved success, the diabetic foot has a tendency to fool you.  After many years of dealing with thousands of diabetic foot complications, I am always humbled by the challenges managing such disorders present to us.  Even ostensibly straightforward problems can succumb to Murphy’s Law – if something can go wrong, it will, and often at the worst possible time!  I think this really characterizes the diabetic foot and exemplifies why we must always be on our toes (forgive the pun) when managing patients with these difficult problems.

Going through my many cases, I found one that presented such a challenge, albeit not a  horrible problem. Nonetheless, it seems to be a recurrent problem in our high risk patients.  This patient, who we will refer to as Mr B., is a 58 year old type 2 diabetic man of 12 year’s duration. He presented to us upon referral from his Primary Care Physician with a gangrenous left great toe stemming from a shoe injury a month or so prior to presentation. He was clinically infected with cellulitis and a had a draining wound at the base of the toe. (Figure 1). 

Figure 1 Gangrenous Left Hallux

As is too often the case, his diabetes was not well controlled with a glycohemoglobin of 8.9%.  White Blood Count (WBC) was at 10,000.  Although neuropathic, he had non-palpable pedal pulses, monophasic Doppler signals, and an Ankle-Brachial Index (ABI) of 0.55, all confirming the presence of critical limb ischemia.  He was promptly admitted and an open hallux amputation was performed to control the infection. As might be expected, this wound soon desiccated due to his ischemia. (Figure 2) Nonetheless, the infection was controlled (adjunctive antimicrobial therapy was also administered).

Figure 2 Post Hallux Amputation

Based on angiography, a femoral-posterior tibial bypass was performed to improve perfusion as a limb salvage measure. (Figure 3) 

Figure 3 Post Femoral-Posterior tibial bypass graft

This was a successful procedure as evidenced by the return of strong biphasic Doppler signals to the foot (although there were no granulations present at the prior hallux amputation site).  Post revascularization transcutaneous oxygen measurement at the midfoot, however, revealed a pressure of only 35mmHg.  Therefore, we performed a fairly classic transmetatarsal amputation (TMA), since we feared that any procedures distal to that level would be unsuccessful. (Figure 4) 

Figure 4 Transmetatarsal amputation – day 3 postoperative

The patient was discharged to a skilled nursing facility (SNF) for rehabilitation, keeping strictly non-weight bearing on the left foot. He was seen weekly in our clinic for postoperative care and evaluation.  His sutures were not removed until 4 weeks postoperatively.  No signs of recurrent infection were evident.

His bypass graft occluded at approximately the 2 month point postoperatively. Vascular surgery did not believe that he had any further options for revascularization at that point. Unfortunately, he developed a large full thickness dehiscence of his amputation wound. Figure 5 shows his foot at 3 months post-operatively.

Figure 5

We were now faced with the conundrum of a failed amputation wound in a neuroischemic extremity with no further options for improving blood flow.  He had been advised that he might be facing a below-knee amputation, since it was doubtful that a foot-sparing amputation at another level would be successful. Fortunately, he was not clinically infected.

Consider now how you might approach this problem, what procedures might you consider, and what modalities (if any) would you utilize to engender healing in this high risk foot?

More to follow next month…

Until next time,

Robert Frykberg, DPM, MPH
PRESENT Editor
Diabetic Limb Salvage

Selected References:

1. Frykberg RG, Zgonis T, Armstrong DG, Driver VR, Giurini JM, Kravitz SR, et al. Diabetic foot disorders. A clinical practice guideline (2006 revision). J Foot Ankle Surg. 2006;45(5 Suppl):S1-66.
2. Aragon-Sanchez J. Seminar review: A review of the basis of surgical treatment of diabetic foot infections. Int J Low Extrem Wounds. 2011;10(1):33-65.
3. Frykberg R, Martin E, Tallis A, Tierney E. A case history of multimodal therapy in healing a complicated diabetic foot wound: negative pressure, dermal replacement and pulsed radio frequency energy therapies. Int Wound J. 2011;8(2):132-9.
4. Lepantalo M, Apelqvist J, Setacci C, Ricco JB, de Donato G, Becker F, et al. Chapter V: Diabetic foot. Eur J Vasc Endovasc Surg. 2011;42 Suppl 2:S60-74.
5. Younger AS, Awwad MA, Kalla TP, de Vries G. Risk factors for failure of transmetatarsal amputation in diabetic patients: a cohort study. Foot Ankle Int. 2009;30(12):1177-82.